Pub Date : 2026-05-01Epub Date: 2026-02-01DOI: 10.1016/j.micrna.2026.208587
H. Shamloo, A. Yazdanpanah Goharrizi
Armchair phosphorene nanoribbon tunnel field-effect transistors (APNR TFETs) are promising candidates for energy-efficient, high-speed nanoelectronics due to their favorable one-dimensional quantum transport properties and tunable bandgap. In this study, we introduce an asymmetric dual-dielectric gate configuration (KLeft = 3.9, KRight = 16) to enhance APNR TFET performance, benchmarking it against uniform low-κ (3.9) and high-κ (16) designs. Quantum transport simulations demonstrate that the proposed asymmetric configuration achieves a high ON-state current (ION = 1.02 × 10−6 A), an ultra-low OFF-state current (IOFF = 1.19 × 10−22 A), and significantly suppresses ambipolar leakage. The device delivers an ON/OFF current ratio of 8.57 × 1015 and a subthreshold swing of 54 mV/dec surpassing the thermionic limit of conventional MOSFETs. Furthermore, it exhibits an intrinsic switching delay of 5 fs/nm, a power-delay product of 3.5 eV/nm, and an average carrier velocity of 7 × 105 m/s. These results highlight the dual-dielectric APNR TFET as a high-performance, low-power candidate for next-generation nanoelectronic devices. Prospects for further optimization include integration with multi-gate architectures and advanced dielectric engineering.
{"title":"Asymmetric dual-dielectric design for enhanced performance in armchair phosphorene nanoribbon TFETs toward low-power nanoelectronic applications","authors":"H. Shamloo, A. Yazdanpanah Goharrizi","doi":"10.1016/j.micrna.2026.208587","DOIUrl":"10.1016/j.micrna.2026.208587","url":null,"abstract":"<div><div>Armchair phosphorene nanoribbon tunnel field-effect transistors (APNR TFETs) are promising candidates for energy-efficient, high-speed nanoelectronics due to their favorable one-dimensional quantum transport properties and tunable bandgap. In this study, we introduce an asymmetric dual-dielectric gate configuration (K<sub>Left</sub> = 3.9, K<sub>Right</sub> = 16) to enhance APNR TFET performance, benchmarking it against uniform low-κ (3.9) and high-κ (16) designs. Quantum transport simulations demonstrate that the proposed asymmetric configuration achieves a high ON-state current (I<sub>ON</sub> = 1.02 × 10<sup>−6</sup> A), an ultra-low OFF-state current (I<sub>OFF</sub> = 1.19 × 10<sup>−22</sup> A), and significantly suppresses ambipolar leakage. The device delivers an ON/OFF current ratio of 8.57 × 10<sup>15</sup> and a subthreshold swing of 54 mV/dec surpassing the thermionic limit of conventional MOSFETs. Furthermore, it exhibits an intrinsic switching delay of 5 fs/nm, a power-delay product of 3.5 eV/nm, and an average carrier velocity of 7 × 10<sup>5</sup> m/s. These results highlight the dual-dielectric APNR TFET as a high-performance, low-power candidate for next-generation nanoelectronic devices. Prospects for further optimization include integration with multi-gate architectures and advanced dielectric engineering.</div></div>","PeriodicalId":100923,"journal":{"name":"Micro and Nanostructures","volume":"213 ","pages":"Article 208587"},"PeriodicalIF":3.0,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146191808","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-05-01Epub Date: 2026-02-04DOI: 10.1016/j.micrna.2026.208600
N. Ajnef , M.M. Habchi , A. Rebey
One of the crucial features of quantum wells (QW) designed for photodetector applications is their optical absorption coefficient. In the present study, the effects of n-type delta (δ) doping on the inter-subband (ISB) optical process in the GaNAsBi/GaAs multi-QW, with sheet donor densities ranging from 2 × 1012 cm−2 to 2 × 1013 cm−2, are investigated. The one-dimensional Schrödinger-Poisson, and charge-neutrality equations are solved self-consistently to obtain the numerical designs of the band engineering, the total ISB optical absorption, and the quantum efficiency spectra. We found that the coupling between the square QW established by the GaNAsBi/GaAs heterostructure and the V-shaped potential provided by the δ-doped layer leads to a restructuring of the confinement potential geometry. The impact of various system parameters on the ISB optical process is examined and discussed, including QW characteristics such as sequence number, well and barrier widths, δ-doping concentration, and its location. The results indicate that the resonant peak of the optical absorption spectra associated with the ISB transition energies lies in the terahertz (THz) frequency range. Therefore, the obtained data, particularly in the frequency range 5-12 THz, are relevant to the development of THz photodetectors with the potential to control their efficiency via an applied external electric field.
{"title":"THz intersubband transitions in n-type δ-doped GaNAsBi/GaAs multi-quantum well structures","authors":"N. Ajnef , M.M. Habchi , A. Rebey","doi":"10.1016/j.micrna.2026.208600","DOIUrl":"10.1016/j.micrna.2026.208600","url":null,"abstract":"<div><div>One of the crucial features of quantum wells (<em>QW</em>) designed for photodetector applications is their optical absorption coefficient. In the present study, the effects of <em>n</em>-type delta (δ) doping on the inter-subband (<em>ISB</em>) optical process in the GaNAsBi/GaAs multi-<em>QW</em>, with sheet donor densities ranging from 2 × 10<sup>12</sup> cm<sup>−2</sup> to 2 × 10<sup>13</sup> cm<sup>−2</sup>, are investigated. The one-dimensional Schrödinger-Poisson, and charge-neutrality equations are solved self-consistently to obtain the numerical designs of the band engineering, the total <em>ISB</em> optical absorption, and the quantum efficiency spectra. We found that the coupling between the square <em>QW</em> established by the GaNAsBi/GaAs heterostructure and the V-shaped potential provided by the δ-doped layer leads to a restructuring of the confinement potential geometry. The impact of various system parameters on the <em>ISB</em> optical process is examined and discussed, including <em>QW</em> characteristics such as sequence number, well and barrier widths, δ-doping concentration, and its location. The results indicate that the resonant peak of the optical absorption spectra associated with the <em>ISB</em> transition energies lies in the terahertz (<em>THz</em>) frequency range. Therefore, the obtained data, particularly in the frequency range <em>5-</em>12 THz, are relevant to the development of <em>THz</em> photodetectors with the potential to control their efficiency via an applied external electric field.</div></div>","PeriodicalId":100923,"journal":{"name":"Micro and Nanostructures","volume":"213 ","pages":"Article 208600"},"PeriodicalIF":3.0,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146192273","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-05-01Epub Date: 2026-02-04DOI: 10.1016/j.micrna.2026.208590
Aqsa Naz , Ismat Bibi , Munawar Iqbal , Farzana Majid , Muhammad Aamir , Qasim Raza , Gul Fatima , Wissem Mnif , Arif Nazir , Norah Alwadai
The development of efficient photocatalysts through simple and sustainable synthesis routes has become a major research priority in recent years. In the present investigation, graphitic carbon nitride coupled Zn–Fe Doped NiCo2O4 composites were synthesized via a co-precipitation route and their ferroelectric, optical, dielectric and photocatalytic features were investigated. X-ray diffraction (XRD) analysis revealed the formation of a single-phase cubic spinel structure of substituted NiCo2O4/g-C3N4 with average crystallite size in the 31–39 nm range. The ferroelectric properties, remnant polarization (Pr), saturation polarization (Ps) and coercivity (Er) were increased with the dopant content. The dielectric loss was decreased and the dielectric constant was increased in nanocomposites with dopant contents. The nanocomposite also revealed higher AC conductivity. The NCZF3/g-C3N4 (x and y = 0.25) showed higher current density than pure NCO/g-C3N4. The PL study revealed that highly doped sample showed the h+-e- recombination low. The bandgap declines from 2.1 to 1.5 eV in highly doped nanocomposite. The photocatalytic activity was assessed by degrading the Acid black 1 (AB1) dye under visible light and NCZF3/g-CN showed the best photocatalytic performance (90%) as compared to NCO/g-CN (63%). The reusability of nanocomposites was studied by recycling the nanocomposite by magnetic separation, which showed promising stability. The NiCo2O4/g-C3N4 is active under solar light irradiation which could have cost-effective applications for wastewater treatment.
{"title":"Graphitic carbon nitride coupled Zn–Fe doped NiCo2O4 nanocomposite: Structural, ferroelectric, dielectric, electrical, optical and solar-light-driven photocatalytic properties","authors":"Aqsa Naz , Ismat Bibi , Munawar Iqbal , Farzana Majid , Muhammad Aamir , Qasim Raza , Gul Fatima , Wissem Mnif , Arif Nazir , Norah Alwadai","doi":"10.1016/j.micrna.2026.208590","DOIUrl":"10.1016/j.micrna.2026.208590","url":null,"abstract":"<div><div>The development of efficient photocatalysts through simple and sustainable synthesis routes has become a major research priority in recent years. In the present investigation, graphitic carbon nitride coupled Zn–Fe Doped NiCo<sub>2</sub>O<sub>4</sub> composites were synthesized via a co-precipitation route and their ferroelectric, optical, dielectric and photocatalytic features were investigated. X-ray diffraction (XRD) analysis revealed the formation of a single-phase cubic spinel structure of substituted NiCo<sub>2</sub>O<sub>4</sub>/g-C<sub>3</sub>N<sub>4</sub> with average crystallite size in the 31–39 nm range. The ferroelectric properties, remnant polarization (Pr), saturation polarization (Ps) and coercivity (Er) were increased with the dopant content. The dielectric loss was decreased and the dielectric constant was increased in nanocomposites with dopant contents. The nanocomposite also revealed higher AC conductivity. The NCZF3/g-C<sub>3</sub>N<sub>4</sub> (x and y = 0.25) showed higher current density than pure NCO/g-C<sub>3</sub>N<sub>4</sub>. The PL study revealed that highly doped sample showed the h<sup>+</sup>-e<sup>-</sup> recombination low. The bandgap declines from 2.1 to 1.5 eV in highly doped nanocomposite. The photocatalytic activity was assessed by degrading the Acid black 1 (AB1) dye under visible light and NCZF3/g-CN showed the best photocatalytic performance (90%) as compared to NCO/g-CN (63%). The reusability of nanocomposites was studied by recycling the nanocomposite by magnetic separation, which showed promising stability. The NiCo<sub>2</sub>O<sub>4</sub>/g-C<sub>3</sub>N<sub>4</sub> is active under solar light irradiation which could have cost-effective applications for wastewater treatment.</div></div>","PeriodicalId":100923,"journal":{"name":"Micro and Nanostructures","volume":"213 ","pages":"Article 208590"},"PeriodicalIF":3.0,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146191823","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-05-01Epub Date: 2026-02-06DOI: 10.1016/j.micrna.2026.208588
Hongze Li , Jinping Tian , Rongcao Yang
Dynamically switchable terahertz (THz) chiral metamaterial with quadruple functions integrating vanadium dioxide () and Dirac semimetal (DS) is proposed and numerically validated. First, by exploiting the reversible phase transition characteristics of , dynamic switching between linear polarization (LP) absorption, circular dichroism (CD) and linear-to-circular (LTC) polarization conversion is achieved. Simulation results reveal that when is in the insulating phase and the Fermi level of DS is tuned to 250 meV, pronounced CD can be obtained, with a maximum CD value of 0.978 at 2.12 THz. Under this condition, the designed structure exhibits nearly perfect absorption for right-handed circularly polarized (RCP) waves, while left-handed circularly polarized (LCP) waves will be almost completely reflected. Compared with conventional CD devices, the proposed configuration allows for tunable strong CD through the Fermi-level modulation of DS. Besides, research results also shows that when the incident waves are LP ones, they will be converted into RCP or LCP waves at 2.12 THz. In contrast, when undergoes the transition to the metallic state and the Fermi level of DS is adjusted to 30 meV, the metamaterial demonstrates broadband perfect absorption for LP wave within 0.2–1.2 THz, with an absorption peak of over 0.99 at 0.58 THz. Meanwhile, the absorption intensity can be adjusted by changing the conductivity of . In addition, anomalous beam deflection can be realized by constructing a super unit cell through the composition of eight rotated unit cells in terms of geometric phase principle, and the beam with different frequencies will be deflected to different angles upon reflection. These findings enrich the concept of dynamic chiral control of THz waves and provide new opportunities for the design of tunable THz chiral metamaterials.
{"title":"A dynamically tunable chiral metamaterial with strong circular dichroism based on vanadium dioxide and Dirac semimetals","authors":"Hongze Li , Jinping Tian , Rongcao Yang","doi":"10.1016/j.micrna.2026.208588","DOIUrl":"10.1016/j.micrna.2026.208588","url":null,"abstract":"<div><div>Dynamically switchable terahertz (THz) chiral metamaterial with quadruple functions integrating vanadium dioxide (<span><math><mrow><msub><mtext>VO</mtext><mn>2</mn></msub></mrow></math></span>) and Dirac semimetal (DS) is proposed and numerically validated. First, by exploiting the reversible phase transition characteristics of <span><math><mrow><msub><mtext>VO</mtext><mn>2</mn></msub></mrow></math></span>, dynamic switching between linear polarization (LP) absorption, circular dichroism (CD) and linear-to-circular (LTC) polarization conversion is achieved. Simulation results reveal that when <span><math><mrow><msub><mtext>VO</mtext><mn>2</mn></msub></mrow></math></span> is in the insulating phase and the Fermi level of DS is tuned to 250 meV, pronounced CD can be obtained, with a maximum CD value of 0.978 at 2.12 THz. Under this condition, the designed structure exhibits nearly perfect absorption for right-handed circularly polarized (RCP) waves, while left-handed circularly polarized (LCP) waves will be almost completely reflected. Compared with conventional CD devices, the proposed configuration allows for tunable strong CD through the Fermi-level modulation of DS. Besides, research results also shows that when the incident waves are LP ones, they will be converted into RCP or LCP waves at 2.12 THz. In contrast, when <span><math><mrow><msub><mtext>VO</mtext><mn>2</mn></msub></mrow></math></span> undergoes the transition to the metallic state and the Fermi level of DS is adjusted to 30 meV, the metamaterial demonstrates broadband perfect absorption for LP wave within 0.2–1.2 THz, with an absorption peak of over 0.99 at 0.58 THz. Meanwhile, the absorption intensity can be adjusted by changing the conductivity of <span><math><mrow><msub><mtext>VO</mtext><mn>2</mn></msub></mrow></math></span>. In addition, anomalous beam deflection can be realized by constructing a super unit cell through the composition of eight rotated unit cells in terms of geometric phase principle, and the beam with different frequencies will be deflected to different angles upon reflection. These findings enrich the concept of dynamic chiral control of THz waves and provide new opportunities for the design of tunable THz chiral metamaterials.</div></div>","PeriodicalId":100923,"journal":{"name":"Micro and Nanostructures","volume":"213 ","pages":"Article 208588"},"PeriodicalIF":3.0,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146192279","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Tunnel Field-Effect Transistors (TFETs) have attracted attention as possible substitutes for conventional MOSFETs in future ultra-low-power digital and analog circuit applications. Owing to their unique characteristics that include subthreshold swing (SS) below 60 mV/decade, immunity against short-channel effects (SCEs), and extremely low OFF-state current (IOFF), TFETs present a compelling solution for energy-efficient device design. This review provides an in-depth study of the DC and analog/RF performance of III-V-based TFETs. III-V materials are favored for their superior tunneling capabilities, enabled by narrow bandgaps and low carrier effective masses. The review highlights recent advancements in TFET design and performance optimization. The effects of temperature variations and interface trap charges on TFET operation are also discussed. Alongside device structures and performance analysis, this review discusses widely used TCAD simulation platforms, such as Silvaco ATLAS and Synopsys Sentaurus, which are essential for modelling and analyzing TFET operation and design. Finally, this review covers the applications of III-V-based TFETs and highlights the future prospects of using TFETs.
{"title":"A comprehensive review on III-V TFET design optimization","authors":"Mohamed Elnaggar , Yasmine Elogail , Mostafa Fedawy , Ahmed Shaker","doi":"10.1016/j.micrna.2026.208601","DOIUrl":"10.1016/j.micrna.2026.208601","url":null,"abstract":"<div><div>Tunnel Field-Effect Transistors (TFETs) have attracted attention as possible substitutes for conventional MOSFETs in future ultra-low-power digital and analog circuit applications. Owing to their unique characteristics that include subthreshold swing (SS) below 60 mV/decade, immunity against short-channel effects (SCEs), and extremely low OFF-state current (I<sub>OFF</sub>), TFETs present a compelling solution for energy-efficient device design. This review provides an in-depth study of the DC and analog/RF performance of III-V-based TFETs. III-V materials are favored for their superior tunneling capabilities, enabled by narrow bandgaps and low carrier effective masses. The review highlights recent advancements in TFET design and performance optimization. The effects of temperature variations and interface trap charges on TFET operation are also discussed. Alongside device structures and performance analysis, this review discusses widely used TCAD simulation platforms, such as Silvaco ATLAS and Synopsys Sentaurus, which are essential for modelling and analyzing TFET operation and design. Finally, this review covers the applications of III-V-based TFETs and highlights the future prospects of using TFETs.</div></div>","PeriodicalId":100923,"journal":{"name":"Micro and Nanostructures","volume":"213 ","pages":"Article 208601"},"PeriodicalIF":3.0,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146191826","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-05-01Epub Date: 2026-01-31DOI: 10.1016/j.micrna.2026.208585
Nirlipta Kar, Sushanta Kumar Kamilla
The detection of hazardous volatile organic compounds such as acetone (CH3–CO–CH3), a highly flammable and widely used industrial solvent, is still a challenge at low temperature with fast response and recovery time. This study examines the impact of magnetic behaviour of Ni and Co doped ZnO (NZO and CZO) on the acetone sensing properties at room temperature (RT) processed by using thermo-vibrational annealing and vibrational dry-quenching (TVA) technique. Comparative analysis reveals that NZO processed through TVA exhibits better ferromagnetic behaviour and enhanced gas sensing performance compared to CZO, despite both having similarly reduced grain sizes. When exposed to 10 ppm of acetone at RT, NZO demonstrated higher sensitivity than CZO. Notably, NZO and CZO pellets processed via TVA shows higher sensitivity and shorter response/recovery time at RT over conventionally annealed counterparts. This sensor of NZO processed with TVA is found to have ∼37 % of sensitivity with fast response time of ∼23 s at RT. A strong correlation is observed between gas sensitivity and the squareness ratio of the magnetic hysteresis, highlighting the significant role of magnetic characteristics in gas sensing behavior. The temperature versus sensing behaviour indicates that the acetone response in Ni-doped ZnO is governed by coupled magneto-electronic interactions near the Curie temperature. Additionally, photoluminescence analysis reveals an increased oxygen vacancy concentration in Ni-doped samples, contributing to greater surface reactivity via enhanced active oxygen species. The increased surface area, the presence of surface dangling bonds of the TVA-processed samples further contributes to the observed performance. The exceptional sensing ability of TVA-processed NZO is primarily attributed to its robust ferromagnetic characteristics, establishing TVA as a promising route for tuning the multifunctional properties of oxide semiconductors.
{"title":"Effect of magnetic behavior of ZnO-based diluted magnetic semiconductors processed through TVA technique on room temperature CH3–CO–CH3 sensing properties","authors":"Nirlipta Kar, Sushanta Kumar Kamilla","doi":"10.1016/j.micrna.2026.208585","DOIUrl":"10.1016/j.micrna.2026.208585","url":null,"abstract":"<div><div>The detection of hazardous volatile organic compounds such as acetone (CH<sub>3</sub>–CO–CH<sub>3</sub>), a highly flammable and widely used industrial solvent, is still a challenge at low temperature with fast response and recovery time. This study examines the impact of magnetic behaviour of Ni and Co doped ZnO (NZO and CZO) on the acetone sensing properties at room temperature (RT) processed by using thermo-vibrational annealing and vibrational dry-quenching (TVA) technique. Comparative analysis reveals that NZO processed through TVA exhibits better ferromagnetic behaviour and enhanced gas sensing performance compared to CZO, despite both having similarly reduced grain sizes. When exposed to 10 ppm of acetone at RT, NZO demonstrated higher sensitivity than CZO. Notably, NZO and CZO pellets processed via TVA shows higher sensitivity and shorter response/recovery time at RT over conventionally annealed counterparts. This sensor of NZO processed with TVA is found to have ∼37 % of sensitivity with fast response time of ∼23 s at RT. A strong correlation is observed between gas sensitivity and the squareness ratio of the magnetic hysteresis, highlighting the significant role of magnetic characteristics in gas sensing behavior. The temperature versus sensing behaviour indicates that the acetone response in Ni-doped ZnO is governed by coupled magneto-electronic interactions near the Curie temperature. Additionally, photoluminescence analysis reveals an increased oxygen vacancy concentration in Ni-doped samples, contributing to greater surface reactivity via enhanced active oxygen species. The increased surface area, the presence of surface dangling bonds of the TVA-processed samples further contributes to the observed performance. The exceptional sensing ability of TVA-processed NZO is primarily attributed to its robust ferromagnetic characteristics, establishing TVA as a promising route for tuning the multifunctional properties of oxide semiconductors.</div></div>","PeriodicalId":100923,"journal":{"name":"Micro and Nanostructures","volume":"213 ","pages":"Article 208585"},"PeriodicalIF":3.0,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146098588","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-05-01Epub Date: 2026-02-05DOI: 10.1016/j.micrna.2026.208589
Reza Mohammadi , Mohsen Hayati , Farzin Shama
This paper presents a numerical simulation study of a novel monolithic double-junction (tandem) solar cell structure. The proposed device architecture utilizes two copper indium gallium diselenide (CIGS) subcells with different, carefully engineered bandgaps. These are integrated with tungsten disulfide (WS2), serving as an environmentally benign and efficient electron transport layer, and zinc oxide (ZnO) as a window layer. Device modeling was performed using the Silvaco ATLAS framework to investigate and optimize the photovoltaic performance of this innovative CIGS/CIGS tandem configuration. Key design parameters, including the composition-dependent bandgaps of the CIGS absorbers and layer thicknesses, were meticulously optimized to achieve high power conversion efficiency while ensuring current matching between the top and bottom subcells. The simulation results demonstrate the significant potential of this structure. The optimized CIGS/CIGS tandem solar cell yielded a remarkable power conversion efficiency (η) of 41.10%, with an open-circuit voltage (Voc) of 1.80 V, a short-circuit current density (Jsc) of 27.71 mA/cm2, and a fill factor (FF) of 82.40% under standard AM1.5G illumination. This study highlights the promise of all-CIGS-based tandem architectures incorporating 2D transition metal dichalcogenides like WS2 as a viable pathway towards next-generation, ultra-high-performance solar cells. We provide critical insights into the design of the essential Tunnel Recombination Junction (TRJ) and discuss the key practical fabrication and mechanical challenges that must be addressed for experimental realization.
{"title":"High-efficiency monolithic CIGS/CIGS tandem solar cell with WS2 buffer layers","authors":"Reza Mohammadi , Mohsen Hayati , Farzin Shama","doi":"10.1016/j.micrna.2026.208589","DOIUrl":"10.1016/j.micrna.2026.208589","url":null,"abstract":"<div><div>This paper presents a numerical simulation study of a novel monolithic double-junction (tandem) solar cell structure. The proposed device architecture utilizes two copper indium gallium diselenide (CIGS) subcells with different, carefully engineered bandgaps. These are integrated with tungsten disulfide (WS<sub>2</sub>), serving as an environmentally benign and efficient electron transport layer, and zinc oxide (ZnO) as a window layer. Device modeling was performed using the Silvaco ATLAS framework to investigate and optimize the photovoltaic performance of this innovative CIGS/CIGS tandem configuration. Key design parameters, including the composition-dependent bandgaps of the CIGS absorbers and layer thicknesses, were meticulously optimized to achieve high power conversion efficiency while ensuring current matching between the top and bottom subcells. The simulation results demonstrate the significant potential of this structure. The optimized CIGS/CIGS tandem solar cell yielded a remarkable power conversion efficiency (η) of 41.10%, with an open-circuit voltage (Voc) of 1.80 V, a short-circuit current density (Jsc) of 27.71 mA/cm<sup>2</sup>, and a fill factor (FF) of 82.40% under standard AM1.5G illumination. This study highlights the promise of all-CIGS-based tandem architectures incorporating 2D transition metal dichalcogenides like WS<sub>2</sub> as a viable pathway towards next-generation, ultra-high-performance solar cells. We provide critical insights into the design of the essential Tunnel Recombination Junction (TRJ) and discuss the key practical fabrication and mechanical challenges that must be addressed for experimental realization.</div></div>","PeriodicalId":100923,"journal":{"name":"Micro and Nanostructures","volume":"213 ","pages":"Article 208589"},"PeriodicalIF":3.0,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146192272","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This study presents a comprehensive investigation of graphene/silicon (Gr/Si) Schottky junction solar cells using an integrated approach that combines density functional theory (DFT) with Technology Computer-Aided Design (TCAD, Silvaco) simulations. DFT calculations were used to extract key optoelectronic properties of graphene, including refractive index, extinction coefficient, absorption, and interface charge density, which were incorporated into Silvaco TCAD simulations to model device behavior. The influence of graphene thickness, interfacial engineering, and graphene electron affinity on photovoltaic performance was systematically examined. The results show that graphene thickness strongly controls the tradeoff between optical transparency and electrical conductivity, with three graphene layers providing optimal performance. At this thickness, the device achieves a short-circuit current density of ∼23 mA/cm2 and a fill factor of ∼83 %, while thicker layers reduce efficiency due to increased optical losses and recombination. Mechanical stress analysis reveals that increasing graphene layers amplifies interfacial stress and trap density, whereas TiO2 emerges as the most effective stress-relieving interface layer due to its low residual stress and reduced defect formation. Tuning the graphene electron affinity (χGr) from 4.1 to 4.7 eV, an optimum is observed at χGr ≈ 4.4 eV (work function ≈ 5.5 eV), yielding a maximum power conversion efficiency of 19.26 %, with a short-circuit current density of 25 mA/cm2, an open-circuit voltage of 0.92 V, and a fill factor of 83.6 %. These findings demonstrate that controlled graphene thickness, TiO2-based interface passivation, and electron-affinity optimization are key to achieving high-efficiency Gr/Si Schottky junction solar cells.
{"title":"TCAD-DFT based modeling and optimization of Graphene/Silicon Schottky junction solar cells","authors":"Manoj Kumar , Purnendu Shekhar Pandey , Gvs Manoj Kumar , Akash Kumar Pradhan , M. Sudhakara Reddy , Anita Gehlot","doi":"10.1016/j.micrna.2026.208581","DOIUrl":"10.1016/j.micrna.2026.208581","url":null,"abstract":"<div><div>This study presents a comprehensive investigation of graphene/silicon (Gr/Si) Schottky junction solar cells using an integrated approach that combines density functional theory (DFT) with Technology Computer-Aided Design (TCAD, Silvaco) simulations. DFT calculations were used to extract key optoelectronic properties of graphene, including refractive index, extinction coefficient, absorption, and interface charge density, which were incorporated into Silvaco TCAD simulations to model device behavior. The influence of graphene thickness, interfacial engineering, and graphene electron affinity on photovoltaic performance was systematically examined. The results show that graphene thickness strongly controls the tradeoff between optical transparency and electrical conductivity, with three graphene layers providing optimal performance. At this thickness, the device achieves a short-circuit current density of ∼23 mA/cm<sup>2</sup> and a fill factor of ∼83 %, while thicker layers reduce efficiency due to increased optical losses and recombination. Mechanical stress analysis reveals that increasing graphene layers amplifies interfacial stress and trap density, whereas TiO<sub>2</sub> emerges as the most effective stress-relieving interface layer due to its low residual stress and reduced defect formation. Tuning the graphene electron affinity (χ<sub>Gr</sub>) from 4.1 to 4.7 eV, an optimum is observed at χ<sub>Gr</sub> ≈ 4.4 eV (work function ≈ 5.5 eV), yielding a maximum power conversion efficiency of 19.26 %, with a short-circuit current density of 25 mA/cm<sup>2</sup>, an open-circuit voltage of 0.92 V, and a fill factor of 83.6 %. These findings demonstrate that controlled graphene thickness, TiO<sub>2</sub>-based interface passivation, and electron-affinity optimization are key to achieving high-efficiency Gr/Si Schottky junction solar cells.</div></div>","PeriodicalId":100923,"journal":{"name":"Micro and Nanostructures","volume":"212 ","pages":"Article 208581"},"PeriodicalIF":3.0,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146079289","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-04-01Epub Date: 2026-01-28DOI: 10.1016/j.micrna.2026.208583
D. Sekyi-Arthur , S.Y. Mensah , K.A. Dompreh , F. Amo-Mensah
Herein, we present a comprehensive theoretical and computational investigation of both the longitudinal () and off-diagonal () thermoelectric performance of GaAs–AlGaAs superlattices subjected to combined alternating electric and perpendicular magnetic fields. Using the semiclassical Boltzmann transport framework, the model incorporates miniband electron dynamics, impurity and phonon scattering, donor activation, and both electronic and lattice contributions to heat transport. The applied magnetic field couples the longitudinal and transverse channels, giving rise to non-zero off-diagonal thermopower () and electrical conductivity () components, while simultaneously modifying the longitudinal thermoelectric response (, ). Parametric analyses across temperature, miniband width, carrier density, chemical potential, and lattice thermal conductivity reveal that quantum confinement and magneto-thermoelectric coupling can substantially enhance both and , with the transverse component showing particularly strong gains at moderate magnetic fields at sub-room temperatures. These results demonstrate the potential of engineered GaAs–AlGaAs superlattices for high-efficiency longitudinal and transverse thermoelectric energy conversion, providing a predictive framework for optimising anisotropic thermoelectricity in low-dimensional semiconductor systems.
{"title":"Thermomagnetic transport and field-tunable figures of merit in GaAs/AlGaAs superlattices","authors":"D. Sekyi-Arthur , S.Y. Mensah , K.A. Dompreh , F. Amo-Mensah","doi":"10.1016/j.micrna.2026.208583","DOIUrl":"10.1016/j.micrna.2026.208583","url":null,"abstract":"<div><div>Herein, we present a comprehensive theoretical and computational investigation of both the longitudinal (<span><math><mrow><mi>Z</mi><msub><mrow><mi>T</mi></mrow><mrow><mi>x</mi><mi>x</mi></mrow></msub></mrow></math></span>) and off-diagonal (<span><math><mrow><mi>Z</mi><msub><mrow><mi>T</mi></mrow><mrow><mi>x</mi><mi>y</mi></mrow></msub></mrow></math></span>) thermoelectric performance of GaAs–AlGaAs superlattices subjected to combined alternating electric and perpendicular magnetic fields. Using the semiclassical Boltzmann transport framework, the model incorporates miniband electron dynamics, impurity and phonon scattering, donor activation, and both electronic and lattice contributions to heat transport. The applied magnetic field couples the longitudinal and transverse channels, giving rise to non-zero off-diagonal thermopower (<span><math><msub><mrow><mi>α</mi></mrow><mrow><mi>x</mi><mi>y</mi></mrow></msub></math></span>) and electrical conductivity (<span><math><msub><mrow><mi>σ</mi></mrow><mrow><mi>x</mi><mi>y</mi></mrow></msub></math></span>) components, while simultaneously modifying the longitudinal thermoelectric response (<span><math><msub><mrow><mi>α</mi></mrow><mrow><mi>x</mi><mi>x</mi></mrow></msub></math></span>, <span><math><msub><mrow><mi>σ</mi></mrow><mrow><mi>x</mi><mi>x</mi></mrow></msub></math></span>). Parametric analyses across temperature, miniband width, carrier density, chemical potential, and lattice thermal conductivity reveal that quantum confinement and magneto-thermoelectric coupling can substantially enhance both <span><math><mrow><mi>Z</mi><msub><mrow><mi>T</mi></mrow><mrow><mi>x</mi><mi>x</mi></mrow></msub></mrow></math></span> and <span><math><mrow><mi>Z</mi><msub><mrow><mi>T</mi></mrow><mrow><mi>x</mi><mi>y</mi></mrow></msub></mrow></math></span>, with the transverse component showing particularly strong gains at moderate magnetic fields at sub-room temperatures. These results demonstrate the potential of engineered GaAs–AlGaAs superlattices for high-efficiency longitudinal and transverse thermoelectric energy conversion, providing a predictive framework for optimising anisotropic thermoelectricity in low-dimensional semiconductor systems.</div></div>","PeriodicalId":100923,"journal":{"name":"Micro and Nanostructures","volume":"212 ","pages":"Article 208583"},"PeriodicalIF":3.0,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146079288","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-04-01Epub Date: 2026-01-17DOI: 10.1016/j.micrna.2026.208577
Bilal Ahmed , Muhammad Bilal Tahir , Gharam A. Alharshan
This paper offers a thorough first-principles examination of the structural, electronic, optical, mechanical, magnetic, thermodynamic, and hydrogen storage characteristics of SiX3H8 (X = Ti, V, Cr, Mn, Fe) hydrides utilizing density functional theory (DFT). All of the compounds crystallize in a cubic perovskite-type framework (space group Pm3 m) and have negative formation enthalpies and phonon spectra that don't have any imaginary modes. This shows that they are stable in both thermodynamic and dynamic terms. Electronic band structures and density-of-states investigations demonstrate metallic behavior in all hydrides, characterized by strong d-orbital contributions near the Fermi level, which enable fast charge transfer during hydrogen adsorption and desorption. Optical computations show that the materials have strong dielectric responses, high refractive indices, high absorption coefficients, and high optical conductivity. This suggests that they could be used for both hydrogen storage and optoelectronic applications. Mechanical tests show that all of the compounds meet Born stability standards and are brittle with different levels of anisotropy. SiMn3H8 is the stiffest of the bunch. Thermodynamic data indicate consistent increases in internal energy, entropy, and heat capacity as temperature rises. The estimated gravimetric hydrogen storage capacities (3.96–4.49 wt%) surpass conventional material-level screening criteria yet fall short of the U.S. DOE final system-level target (∼6.5 wt%), suggesting that SiX3H8 hydrides are promising candidate materials necessitating further optimization for practical hydrogen storage systems. The computed desorption temperatures (341–441 K) are also within or close to practical operational limits. The structural stability, metallicity, favorable thermodynamic behavior, and competitive hydrogen storage features of SiX3H8 hydrides make them strong candidates for advanced solid-state hydrogen H2 devices and energy-related applications that do more than one thing.
{"title":"First-principles modelling of physical characteristics of SiX3H8 (X = Ti, V, Cr, Mn, Fe) hydrides for hydrogen storage and energy harvesting applications","authors":"Bilal Ahmed , Muhammad Bilal Tahir , Gharam A. Alharshan","doi":"10.1016/j.micrna.2026.208577","DOIUrl":"10.1016/j.micrna.2026.208577","url":null,"abstract":"<div><div>This paper offers a thorough first-principles examination of the structural, electronic, optical, mechanical, magnetic, thermodynamic, and hydrogen storage characteristics of SiX<sub>3</sub>H<sub>8</sub> (X = Ti, V, Cr, Mn, Fe) hydrides utilizing density functional theory (DFT). All of the compounds crystallize in a cubic perovskite-type framework (space group Pm3 m) and have negative formation enthalpies and phonon spectra that don't have any imaginary modes. This shows that they are stable in both thermodynamic and dynamic terms. Electronic band structures and density-of-states investigations demonstrate metallic behavior in all hydrides, characterized by strong d-orbital contributions near the Fermi level, which enable fast charge transfer during hydrogen adsorption and desorption. Optical computations show that the materials have strong dielectric responses, high refractive indices, high absorption coefficients, and high optical conductivity. This suggests that they could be used for both hydrogen storage and optoelectronic applications. Mechanical tests show that all of the compounds meet Born stability standards and are brittle with different levels of anisotropy. SiMn<sub>3</sub>H<sub>8</sub> is the stiffest of the bunch. Thermodynamic data indicate consistent increases in internal energy, entropy, and heat capacity as temperature rises. The estimated gravimetric hydrogen storage capacities (3.96–4.49 wt%) surpass conventional material-level screening criteria yet fall short of the U.S. DOE final system-level target (∼6.5 wt%), suggesting that SiX<sub>3</sub>H<sub>8</sub> hydrides are promising candidate materials necessitating further optimization for practical hydrogen storage systems. The computed desorption temperatures (341–441 K) are also within or close to practical operational limits. The structural stability, metallicity, favorable thermodynamic behavior, and competitive hydrogen storage features of SiX<sub>3</sub>H<sub>8</sub> hydrides make them strong candidates for advanced solid-state hydrogen H<sub>2</sub> devices and energy-related applications that do more than one thing.</div></div>","PeriodicalId":100923,"journal":{"name":"Micro and Nanostructures","volume":"212 ","pages":"Article 208577"},"PeriodicalIF":3.0,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146026162","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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