Pub Date : 2026-01-01Epub Date: 2025-10-15DOI: 10.1016/j.physe.2025.116388
Bratati Mukhopadhyay, P.K. Basu
Direct bandgap Ge1-xSnx (x > 0.08) alloys have emerged as highly promising materials for next-generation high-speed electronic, thermoelectric, and photonic devices, owing to their tunable band structure and compatibility with standard CMOS technology on silicon platforms. The transition from indirect to direct band gap for Sn concentration exceeding 8 % has made these alloys attractive for photonic applications such as mid-infrared lasers, modulators, and photodetectors, particularly in the 2–5 μm wavelength range. An earlier study predicted that the electron mobility in the non-degenerate Ge1-xSnx alloy would increase by 50 times for x ≥ 0.08 from the value in pure Ge (3900 cm2/V-sec) due to increased separation between Γ and L valleys and consequent reduction in intervalley scattering. In the present work, a realistic theoretical estimate is made of mobility of bulk Ge1-xSnx under both non-degenerate and degenerate condition for a wide range of Sn concentration (0 < x < 0.2) covering indirect and direct bandgap nature of the alloy. The theoretical values of mobility show excellent agreement with the experimental values reported for x = 0.02, and satisfactory agreement for x = 0.125. For the calculation of mobility, scattering by phonons (deformation potential acoustic, optical and intervalley), alloy-disorder, impurity as well as electron-electron scattering have been taken into consideration.
{"title":"Analytical modeling of electron mobility in non-degenerate and degenerate bulk n-Ge1-xSnx","authors":"Bratati Mukhopadhyay, P.K. Basu","doi":"10.1016/j.physe.2025.116388","DOIUrl":"10.1016/j.physe.2025.116388","url":null,"abstract":"<div><div>Direct bandgap Ge<sub>1-x</sub>Sn<sub>x</sub> (x > 0.08) alloys have emerged as highly promising materials for next-generation high-speed electronic, thermoelectric, and photonic devices, owing to their tunable band structure and compatibility with standard CMOS technology on silicon platforms. The transition from indirect to direct band gap for Sn concentration exceeding 8 % has made these alloys attractive for photonic applications such as mid-infrared lasers, modulators, and photodetectors, particularly in the 2–5 μm wavelength range. An earlier study predicted that the electron mobility in the non-degenerate Ge<sub>1-x</sub>Sn<sub>x</sub> alloy would increase by 50 times for x ≥ 0.08 from the value in pure Ge (3900 cm<sup>2</sup>/V-sec) due to increased separation between Γ and L valleys and consequent reduction in intervalley scattering. In the present work, a realistic theoretical estimate is made of mobility of bulk Ge<sub>1-x</sub>Sn<sub>x</sub> under both non-degenerate and degenerate condition for a wide range of Sn concentration (0 < x < 0.2) covering indirect and direct bandgap nature of the alloy. The theoretical values of mobility show excellent agreement with the experimental values reported for x = 0.02, and satisfactory agreement for x = 0.125. For the calculation of mobility, scattering by phonons (deformation potential acoustic, optical and intervalley), alloy-disorder, impurity as well as electron-electron scattering have been taken into consideration.</div></div>","PeriodicalId":20181,"journal":{"name":"Physica E-low-dimensional Systems & Nanostructures","volume":"175 ","pages":"Article 116388"},"PeriodicalIF":2.9,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145324746","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-01Epub Date: 2025-09-23DOI: 10.1016/j.physe.2025.116379
A. Bahlaoui , Y. Zahidi
The paper discusses the Klein tunneling and Fabry–Pérot resonances of charge carriers through a rectangular potential barrier in twisted bilayer graphene. Within the framework of the low-energy excitations, the transmission probability and the conductance are obtained depending on the parameters of the problem. Owing to the moiré-induced anisotropy of the Hamiltonian in twisted bilayer graphene, the propagation of charge carriers exhibits an anisotropic behavior in Klein tunneling and Fabry–Pérot resonances. Moreover, we show that the anisotropy of the charge carriers induces asymmetry and deflection in the Fabry–Pérot resonances and Klein tunneling, and they are extremely sensitive to the height of the potential applied. Additionally, we found that the conductance is strongly sensitive to the barrier height but weakly sensitive to the barrier width. Therefore, it is possible to control the maxima and minima of the conductance of charge carriers in twisted bilayer graphene. With our results, we gain an in-depth understanding of tunneling properties in twisted bilayer graphene, which may help in the development and design of novel electronic nanodevices based on anisotropic 2D materials.
{"title":"Klein tunneling and Fabry–Pérot resonances in twisted bilayer graphene","authors":"A. Bahlaoui , Y. Zahidi","doi":"10.1016/j.physe.2025.116379","DOIUrl":"10.1016/j.physe.2025.116379","url":null,"abstract":"<div><div>The paper discusses the Klein tunneling and Fabry–Pérot resonances of charge carriers through a rectangular potential barrier in twisted bilayer graphene. Within the framework of the low-energy excitations, the transmission probability and the conductance are obtained depending on the parameters of the problem. Owing to the moiré-induced anisotropy of the Hamiltonian in twisted bilayer graphene, the propagation of charge carriers exhibits an anisotropic behavior in Klein tunneling and Fabry–Pérot resonances. Moreover, we show that the anisotropy of the charge carriers induces asymmetry and deflection in the Fabry–Pérot resonances and Klein tunneling, and they are extremely sensitive to the height of the potential applied. Additionally, we found that the conductance is strongly sensitive to the barrier height but weakly sensitive to the barrier width. Therefore, it is possible to control the maxima and minima of the conductance of charge carriers in twisted bilayer graphene. With our results, we gain an in-depth understanding of tunneling properties in twisted bilayer graphene, which may help in the development and design of novel electronic nanodevices based on anisotropic 2D materials.</div></div>","PeriodicalId":20181,"journal":{"name":"Physica E-low-dimensional Systems & Nanostructures","volume":"175 ","pages":"Article 116379"},"PeriodicalIF":2.9,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145159088","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-01Epub Date: 2025-09-30DOI: 10.1016/j.physe.2025.116381
Carlos Magno O. Pereira, Edilberto O. Silva
We predict a new class of quantum Hall phenomena in completely neutral systems, demonstrating that the interplay between radial electric fields and dipole moments induces exact quantization without Landau levels or external magnetic fields. Contrary to conventional wisdom, our theory reveals that: (i) the singularity of line charges does not destroy topological protection, (ii) spin control of quantization emerges from boundary conditions alone, and (iii) the effect persists up to 25 K, surpassing typical neutral systems. These findings establish electric field engineering as a viable route to topological matter beyond magnetic paradigms.
{"title":"Quantum Hall-like effect for neutral particles with magnetic dipole moments in a quantum dot","authors":"Carlos Magno O. Pereira, Edilberto O. Silva","doi":"10.1016/j.physe.2025.116381","DOIUrl":"10.1016/j.physe.2025.116381","url":null,"abstract":"<div><div>We predict a new class of quantum Hall phenomena in completely neutral systems, demonstrating that the interplay between radial electric fields and dipole moments induces exact <span><math><mrow><msup><mrow><mi>e</mi></mrow><mrow><mn>2</mn></mrow></msup><mo>/</mo><mi>h</mi></mrow></math></span> quantization without Landau levels or external magnetic fields. Contrary to conventional wisdom, our theory reveals that: (i) the singularity of line charges does not destroy topological protection, (ii) spin control of quantization emerges from boundary conditions alone, and (iii) the effect persists up to 25 K, surpassing typical neutral systems. These findings establish electric field engineering as a viable route to topological matter beyond magnetic paradigms.</div></div>","PeriodicalId":20181,"journal":{"name":"Physica E-low-dimensional Systems & Nanostructures","volume":"175 ","pages":"Article 116381"},"PeriodicalIF":2.9,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145220919","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-01Epub Date: 2025-10-19DOI: 10.1016/j.physe.2025.116390
Mohammed Khalis , Abdennabi Morchid , Rachid Masrour
In this work, we conducted a study aimed at analyzing the impact of uniform electric and magnetic fields on the behavior of charge carriers in a solar cell, with particular focus on the evolution of the photocurrent. Relying on the classical laws of electrodynamics, formulated within a covariant framework, we established the fundamental relationship between the electric field and the magnetic field through the Lorentz force, without initially accounting for collisional interactions. The equations of motion of electrons and holes—describing in particular the cycloidal trajectories of carriers and the drift velocity resulting from the combined action of the two fields—constitute the theoretical basis of our analysis. The application of this formalism to the operation of a solar cell subjected to a perpendicular magnetic field reveals distinct behaviors depending on the region considered. In the depletion region, where the internal electric field is strong, the influence of the magnetic field is significant and markedly alters carrier trajectories. In contrast, in the neutral regions dominated by diffusive transport, its effect remains negligible. The results confirm that increasing the magnetic field intensity leads to a substantial reduction in the photocurrent. For instance, in a silicon solar cell with a surface area of 100 cm2 under illumination at 25 °C, MATLAB simulations indicate a decrease in photocurrent from 3.6 A to 2.6 A as the magnetic field increases from 0 to 50 mT. Experimentally, the study of a photovoltaic module with a surface area of 270 cm2 under illumination shows a reduction in photocurrent from 205 to 90 mA, accompanied by an increase in series resistance from 7.76 to 17.70 Ω, under the same magnetic field variation. When the effect of collisional forces is subsequently incorporated into the modeling, the influence of the magnetic field on both series resistance and photocurrent reduction becomes even more pronounced. These findings highlight an excellent agreement between the modeling—which simultaneously accounts for electrical, magnetic, and collisional contributions—and the experimental observations, thereby validating the relevance of the proposed model and its ability to faithfully describe the behavior of solar cells in the presence of a magnetic field.
{"title":"Impact of magnetic field on photocurrent: A classical electrodynamic study, simulation, and experimental validation","authors":"Mohammed Khalis , Abdennabi Morchid , Rachid Masrour","doi":"10.1016/j.physe.2025.116390","DOIUrl":"10.1016/j.physe.2025.116390","url":null,"abstract":"<div><div>In this work, we conducted a study aimed at analyzing the impact of uniform electric and magnetic fields on the behavior of charge carriers in a solar cell, with particular focus on the evolution of the photocurrent. Relying on the classical laws of electrodynamics, formulated within a covariant framework, we established the fundamental relationship between the electric field <span><math><mrow><mover><mi>E</mi><mo>→</mo></mover></mrow></math></span> and the magnetic field <span><math><mrow><mover><mi>B</mi><mo>→</mo></mover></mrow></math></span> through the Lorentz force, without initially accounting for collisional interactions. The equations of motion of electrons and holes—describing in particular the cycloidal trajectories of carriers and the drift velocity resulting from the combined action of the two fields—constitute the theoretical basis of our analysis. The application of this formalism to the operation of a solar cell subjected to a perpendicular magnetic field reveals distinct behaviors depending on the region considered. In the depletion region, where the internal electric field is strong, the influence of the magnetic field is significant and markedly alters carrier trajectories. In contrast, in the neutral regions dominated by diffusive transport, its effect remains negligible. The results confirm that increasing the magnetic field intensity leads to a substantial reduction in the photocurrent. For instance, in a silicon solar cell with a surface area of 100 cm<sup>2</sup> under <span><math><mrow><mn>1000</mn><mspace></mspace><mi>W</mi><mo>.</mo><msup><mi>m</mi><mrow><mo>−</mo><mn>2</mn></mrow></msup></mrow></math></span> illumination at 25 °C, MATLAB simulations indicate a decrease in photocurrent from 3.6 A to 2.6 A as the magnetic field increases from 0 to 50 mT. Experimentally, the study of a photovoltaic module with a surface area of 270 cm<sup>2</sup> under <span><math><mrow><mn>600</mn><mspace></mspace><mi>W</mi><mo>.</mo><msup><mi>m</mi><mrow><mo>−</mo><mn>2</mn></mrow></msup></mrow></math></span> illumination shows a reduction in photocurrent from 205 to 90 mA, accompanied by an increase in series resistance from 7.76 to 17.70 Ω, under the same magnetic field variation. When the effect of collisional forces is subsequently incorporated into the modeling, the influence of the magnetic field on both series resistance and photocurrent reduction becomes even more pronounced. These findings highlight an excellent agreement between the modeling—which simultaneously accounts for electrical, magnetic, and collisional contributions—and the experimental observations, thereby validating the relevance of the proposed model and its ability to faithfully describe the behavior of solar cells in the presence of a magnetic field.</div></div>","PeriodicalId":20181,"journal":{"name":"Physica E-low-dimensional Systems & Nanostructures","volume":"175 ","pages":"Article 116390"},"PeriodicalIF":2.9,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145363310","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-01Epub Date: 2025-09-11DOI: 10.1016/j.physe.2025.116372
Rongzhi Wang , Jin-Cheng Zheng
Two-dimensional (2D) materials have received considerable attention for next-generation technological applications due to their unique physical properties. Herein, decorated monolayers (O-V-Ga2O3-m, Co doped ZnO-m and Fe cluster@Borophene) with high visible light absorption ability and hydrogen evolution reaction (HER) catalytic performance are reported. Strain and electric field could precisely tune the optical and HER properties of O-V-Ga2O3-m, Co doped ZnO-m and Fe cluster@Borophene. It is shown that the absorption peaks in the visible region red-shift with the increasement of strain or adding electric field. Both strain and electric field can modulate the absorption peaks of decorated monolayers in the visible zone and help to obtain optimal HER performance. These features advocate effective applications of O-V-Ga2O3-m, Co doped ZnO-m and Fe cluster@Borophene in optoelectronic devices and HER electrocatalysts.
{"title":"Tunable optoelectronic and hydrogen evolution reaction properties of decorated 2D materials (Ga2O3 monolayer, ZnO monolayer and borophene)","authors":"Rongzhi Wang , Jin-Cheng Zheng","doi":"10.1016/j.physe.2025.116372","DOIUrl":"10.1016/j.physe.2025.116372","url":null,"abstract":"<div><div>Two-dimensional (2D) materials have received considerable attention for next-generation technological applications due to their unique physical properties. Herein, decorated monolayers (O-V-Ga<sub>2</sub>O<sub>3</sub>-m, Co doped ZnO-m and Fe cluster@Borophene) with high visible light absorption ability and hydrogen evolution reaction (HER) catalytic performance are reported. Strain and electric field could precisely tune the optical and HER properties of O-V-Ga<sub>2</sub>O<sub>3</sub>-m, Co doped ZnO-m and Fe cluster@Borophene. It is shown that the absorption peaks in the visible region red-shift with the increasement of strain or adding electric field. Both strain and electric field can modulate the absorption peaks of decorated monolayers in the visible zone and help to obtain optimal HER performance. These features advocate effective applications of O-V-Ga<sub>2</sub>O<sub>3</sub>-m, Co doped ZnO-m and Fe cluster@Borophene in optoelectronic devices and HER electrocatalysts.</div></div>","PeriodicalId":20181,"journal":{"name":"Physica E-low-dimensional Systems & Nanostructures","volume":"175 ","pages":"Article 116372"},"PeriodicalIF":2.9,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145047640","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-01Epub Date: 2025-10-23DOI: 10.1016/j.physe.2025.116395
Tran Cong Phong , Ta T. Tho , Le T.T. Phuong
We investigate the topological properties of monolayer jacutingaite PtHgSe by analyzing its thermal and magnetic responses under static and dynamic electric fields. In doing so, we use the Kane–Mele model and the semiclassical Boltzmann approach. Through semiclassical calculations, we demonstrate how topological phase transitions induced by these fields are reflected in the material’s electronic heat capacity and Pauli spin susceptibility. We find that in the semimetallic phase, the low-temperature regime exhibits the highest magnitudes of these properties. In contrast, the responses are weaker and stronger for the band insulator and quantum Hall insulator phases, respectively, than the pristine quantum spin Hall insulator phase. This work offers a pathway for detecting topological features in the thermal and magnetic properties of materials.
{"title":"Detecting topological phase transition in monolayer jacutingaite Pt2HgSe3 via thermal and magnetic properties","authors":"Tran Cong Phong , Ta T. Tho , Le T.T. Phuong","doi":"10.1016/j.physe.2025.116395","DOIUrl":"10.1016/j.physe.2025.116395","url":null,"abstract":"<div><div>We investigate the topological properties of monolayer jacutingaite Pt<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span>HgSe<span><math><msub><mrow></mrow><mrow><mn>3</mn></mrow></msub></math></span> by analyzing its thermal and magnetic responses under static and dynamic electric fields. In doing so, we use the Kane–Mele model and the semiclassical Boltzmann approach. Through semiclassical calculations, we demonstrate how topological phase transitions induced by these fields are reflected in the material’s electronic heat capacity and Pauli spin susceptibility. We find that in the semimetallic phase, the low-temperature regime exhibits the highest magnitudes of these properties. In contrast, the responses are weaker and stronger for the band insulator and quantum Hall insulator phases, respectively, than the pristine quantum spin Hall insulator phase. This work offers a pathway for detecting topological features in the thermal and magnetic properties of materials.</div></div>","PeriodicalId":20181,"journal":{"name":"Physica E-low-dimensional Systems & Nanostructures","volume":"175 ","pages":"Article 116395"},"PeriodicalIF":2.9,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145363367","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-01Epub Date: 2025-10-08DOI: 10.1016/j.physe.2025.116383
Raymond J. Hartig , Ioan Grosu , Ionel Ţifrea
<div><div>We investigate the nonlinear thermoelectric transport in a generic nanoscale device connected to two side reservoirs at different temperatures (<span><math><msub><mrow><mi>T</mi></mrow><mrow><mi>L</mi></mrow></msub></math></span> and <span><math><msub><mrow><mi>T</mi></mrow><mrow><mi>R</mi></mrow></msub></math></span>) and chemical potentials (<span><math><msub><mrow><mi>μ</mi></mrow><mrow><mi>L</mi></mrow></msub></math></span> and <span><math><msub><mrow><mi>μ</mi></mrow><mrow><mi>R</mi></mrow></msub></math></span>). We derive equations for the charge (electric) and heat (thermal) currents. These equations allow for the estimation of the second order contributions to the system’s thermoelectric response and the <em>analytical</em> derivation of the first nonlinear contributions to the system’s electric conductance <span><math><msup><mrow><mi>σ</mi></mrow><mrow><mrow><mo>(</mo><mn>2</mn><mo>)</mo></mrow></mrow></msup></math></span>, Seebeck coefficient <span><math><msup><mrow><mi>S</mi></mrow><mrow><mrow><mo>(</mo><mn>2</mn><mo>)</mo></mrow></mrow></msup></math></span>, and electronic thermal conductance <span><math><msubsup><mrow><mi>κ</mi></mrow><mrow><mi>e</mi><mi>l</mi></mrow><mrow><mrow><mo>(</mo><mn>2</mn><mo>)</mo></mrow></mrow></msubsup></math></span>. In the generation mode, when the system’s output power is positive (<span><math><mrow><mi>P</mi><mo>></mo><mn>0</mn></mrow></math></span>), we estimate the maximum output power and efficiency of the system. The results are general and rely on generic dimensionless kinetic transport coefficients <span><math><mrow><msubsup><mrow><mi>K</mi></mrow><mrow><mi>n</mi></mrow><mrow><mi>p</mi></mrow></msubsup><mrow><mo>(</mo><mi>μ</mi><mo>,</mo><mi>T</mi><mo>)</mo></mrow></mrow></math></span> that depends on the system’s characteristic electronic transmission function <span><math><mrow><mi>τ</mi><mrow><mo>(</mo><mi>E</mi><mo>)</mo></mrow></mrow></math></span>. To outline the differences between the linear and nonlinear approximations we consider the particular case of a generalized Fano line-shape electronic transmission function and exactly calculate the dimensionless kinetic transport coefficients in terms of Hurwitz zeta functions and Bernoulli numbers. The output power efficiency of the system is estimated as function of the energy <span><math><mrow><mi>ɛ</mi><mo>=</mo><mrow><mo>(</mo><msub><mrow><mi>E</mi></mrow><mrow><mi>d</mi></mrow></msub><mo>−</mo><mi>μ</mi><mo>)</mo></mrow><mo>/</mo><msub><mrow><mi>k</mi></mrow><mrow><mi>B</mi></mrow></msub><mi>T</mi></mrow></math></span> and broadening <span><math><mrow><mi>γ</mi><mo>=</mo><msub><mrow><mi>Γ</mi></mrow><mrow><mi>d</mi></mrow></msub><mo>/</mo><msub><mrow><mi>k</mi></mrow><mrow><mi>B</mi></mrow></msub><mi>T</mi></mrow></math></span> parameters. These results support the need for higher order terms in the theoretical analysis of the thermoelectric transport in nanoscale devices and allow for the optimization of the system’s propert
{"title":"Nonlinear corrections to the thermoelectric efficiency of a nanoscale device","authors":"Raymond J. Hartig , Ioan Grosu , Ionel Ţifrea","doi":"10.1016/j.physe.2025.116383","DOIUrl":"10.1016/j.physe.2025.116383","url":null,"abstract":"<div><div>We investigate the nonlinear thermoelectric transport in a generic nanoscale device connected to two side reservoirs at different temperatures (<span><math><msub><mrow><mi>T</mi></mrow><mrow><mi>L</mi></mrow></msub></math></span> and <span><math><msub><mrow><mi>T</mi></mrow><mrow><mi>R</mi></mrow></msub></math></span>) and chemical potentials (<span><math><msub><mrow><mi>μ</mi></mrow><mrow><mi>L</mi></mrow></msub></math></span> and <span><math><msub><mrow><mi>μ</mi></mrow><mrow><mi>R</mi></mrow></msub></math></span>). We derive equations for the charge (electric) and heat (thermal) currents. These equations allow for the estimation of the second order contributions to the system’s thermoelectric response and the <em>analytical</em> derivation of the first nonlinear contributions to the system’s electric conductance <span><math><msup><mrow><mi>σ</mi></mrow><mrow><mrow><mo>(</mo><mn>2</mn><mo>)</mo></mrow></mrow></msup></math></span>, Seebeck coefficient <span><math><msup><mrow><mi>S</mi></mrow><mrow><mrow><mo>(</mo><mn>2</mn><mo>)</mo></mrow></mrow></msup></math></span>, and electronic thermal conductance <span><math><msubsup><mrow><mi>κ</mi></mrow><mrow><mi>e</mi><mi>l</mi></mrow><mrow><mrow><mo>(</mo><mn>2</mn><mo>)</mo></mrow></mrow></msubsup></math></span>. In the generation mode, when the system’s output power is positive (<span><math><mrow><mi>P</mi><mo>></mo><mn>0</mn></mrow></math></span>), we estimate the maximum output power and efficiency of the system. The results are general and rely on generic dimensionless kinetic transport coefficients <span><math><mrow><msubsup><mrow><mi>K</mi></mrow><mrow><mi>n</mi></mrow><mrow><mi>p</mi></mrow></msubsup><mrow><mo>(</mo><mi>μ</mi><mo>,</mo><mi>T</mi><mo>)</mo></mrow></mrow></math></span> that depends on the system’s characteristic electronic transmission function <span><math><mrow><mi>τ</mi><mrow><mo>(</mo><mi>E</mi><mo>)</mo></mrow></mrow></math></span>. To outline the differences between the linear and nonlinear approximations we consider the particular case of a generalized Fano line-shape electronic transmission function and exactly calculate the dimensionless kinetic transport coefficients in terms of Hurwitz zeta functions and Bernoulli numbers. The output power efficiency of the system is estimated as function of the energy <span><math><mrow><mi>ɛ</mi><mo>=</mo><mrow><mo>(</mo><msub><mrow><mi>E</mi></mrow><mrow><mi>d</mi></mrow></msub><mo>−</mo><mi>μ</mi><mo>)</mo></mrow><mo>/</mo><msub><mrow><mi>k</mi></mrow><mrow><mi>B</mi></mrow></msub><mi>T</mi></mrow></math></span> and broadening <span><math><mrow><mi>γ</mi><mo>=</mo><msub><mrow><mi>Γ</mi></mrow><mrow><mi>d</mi></mrow></msub><mo>/</mo><msub><mrow><mi>k</mi></mrow><mrow><mi>B</mi></mrow></msub><mi>T</mi></mrow></math></span> parameters. These results support the need for higher order terms in the theoretical analysis of the thermoelectric transport in nanoscale devices and allow for the optimization of the system’s propert","PeriodicalId":20181,"journal":{"name":"Physica E-low-dimensional Systems & Nanostructures","volume":"175 ","pages":"Article 116383"},"PeriodicalIF":2.9,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145267668","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
First principle density functional theory was employed to investigate the physical properties and electronic transition of doped two-dimensional molybdenum disulphide (MoS2) with transition metal niobium (Nb) and vanadium (V) at varying doping concentration. The objective was to study how controlled doping affects the physical characteristics of doped MoS2for potential photodetection application. The obtained result reveal that Nb doping leads to progressive lattice expansion and rapid transition from semiconducting to metallic behavior which is attributed larger atomic radius and fewer valence electrons as compared to Mo. While V doping results in slight contraction of the lattice and a more gradual narrowing of the energy gap and retained it semiconducting nature at low and moderate doping concentration. The elastic properties result shows that Nb doping softens the material significantly than V doped which is due to weakened M − S bonding. The Band structure and total density of states analysis confirm the introduction of impurity levels and p-type character in Nb-doped systems, whereas V-doped systems show hybridization near the Fermi level with localized to semi-metallic transitions. These findings demonstrate that V doping offers a more stable and tunable route for enhancing the optoelectronic performance of MoS2, making it promising candidate for broadband photodetector.
{"title":"Doping-driven physical properties and electronic transition in 2D transition metal dichalcogenides Mo1-XAXS2 (A= [Nb, V], X = 0.25, 0.50, 0.75, 1.00): A First principle study","authors":"Magaji Ismail , Shuaibu Alhassan , Aliyu Kabiru Isiyaku , Sadik Garba Abdu , Shehu Aminu yamusa","doi":"10.1016/j.physe.2025.116373","DOIUrl":"10.1016/j.physe.2025.116373","url":null,"abstract":"<div><div>First principle density functional theory was employed to investigate the physical properties and electronic transition of doped two-dimensional molybdenum disulphide (MoS<sub>2</sub>) with transition metal niobium (Nb) and vanadium (V) at varying doping concentration. The objective was to study how controlled doping affects the physical characteristics of doped MoS<sub>2</sub>for potential photodetection application. The obtained result reveal that Nb doping leads to progressive lattice expansion and rapid transition from semiconducting to metallic behavior which is attributed larger atomic radius and fewer valence electrons as compared to Mo. While V doping results in slight contraction of the lattice and a more gradual narrowing of the energy gap and retained it semiconducting nature at low and moderate doping concentration. The elastic properties result shows that Nb doping softens the material significantly than V doped which is due to weakened M − S bonding. The Band structure and total density of states analysis confirm the introduction of impurity levels and p-type character in Nb-doped systems, whereas V-doped systems show hybridization near the Fermi level with localized to semi-metallic transitions. These findings demonstrate that V doping offers a more stable and tunable route for enhancing the optoelectronic performance of MoS<sub>2</sub>, making it promising candidate for broadband photodetector.</div></div>","PeriodicalId":20181,"journal":{"name":"Physica E-low-dimensional Systems & Nanostructures","volume":"175 ","pages":"Article 116373"},"PeriodicalIF":2.9,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145097116","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The strong visible photoluminescence (PL) in surface-oxidized nanostructured silicon emerges from the interplay between intrinsic Bloch states and oxide-related interfacial defects, making it difficult to isolate their role. Temperature-dependent PL measurements on nanostructured silicon with varying crystallite sizes manifest three distinct decay mechanisms involving band-to-band, band-to-trap and trap-to-trap transitions to multiple emission bands appearing in the convoluted broad PL spectrum. At lower temperatures , PL peak energy associated with the quantum-confined Bloch states exhibits a nearly linear blue shift, governed by a strong inverse power law dependence of the temperature coefficient on the effective crystallite size, while this trend reverses at higher temperatures. Conversely, the defect-related peak energies increase monotonically at a nearly constant rate throughout the experimental temperature range. A general analytical model for finite systems with a separable pseudo-potential effectively estimates the contributions from different decay channels to the PL emission. Theoretical results align well with the experimentally obtained values of the power-law exponents, offering a novel way to distinguish between the radiative recombination channels involving quantum-confined Bloch states and interfacial defects/trap states in nanostructured silicon.
{"title":"Temperature-dependent photoluminescence from nanostructured silicon: role of quantum-confined Bloch states and interfacial defects","authors":"Shayari Basu , Ujjwal Ghanta , Saddam Khan , Manotosh Pramanik , Rajalingam Thangavel , Bipul pal , Syed Minhaz Hossain","doi":"10.1016/j.physe.2025.116380","DOIUrl":"10.1016/j.physe.2025.116380","url":null,"abstract":"<div><div>The strong visible photoluminescence (PL) in surface-oxidized nanostructured silicon emerges from the interplay between intrinsic Bloch states and oxide-related interfacial defects, making it difficult to isolate their role. Temperature-dependent <span><math><mrow><mo>(</mo><mrow><mn>5</mn><mo>−</mo><mn>350</mn><mspace></mspace><mi>K</mi></mrow><mo>)</mo></mrow></math></span> PL measurements on nanostructured silicon with varying crystallite sizes manifest three distinct decay mechanisms involving band-to-band, band-to-trap and trap-to-trap transitions to multiple emission bands appearing in the convoluted broad PL spectrum. At lower temperatures <span><math><mfenced><mrow><mo>≲</mo><mn>225</mn><mspace></mspace><mi>K</mi></mrow></mfenced></math></span>, PL peak energy associated with the quantum-confined Bloch states exhibits a nearly linear blue shift, governed by a strong inverse power law dependence of the temperature coefficient on the effective crystallite size, while this trend reverses at higher temperatures. Conversely, the defect-related peak energies increase monotonically at a nearly constant rate throughout the experimental temperature range. A general analytical model for finite systems with a separable pseudo-potential effectively estimates the contributions from different decay channels to the PL emission. Theoretical results align well with the experimentally obtained values of the power-law exponents, offering a novel way to distinguish between the radiative recombination channels involving quantum-confined Bloch states and interfacial defects/trap states in nanostructured silicon.</div></div>","PeriodicalId":20181,"journal":{"name":"Physica E-low-dimensional Systems & Nanostructures","volume":"175 ","pages":"Article 116380"},"PeriodicalIF":2.9,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145220921","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-01Epub Date: 2025-10-25DOI: 10.1016/j.physe.2025.116394
M. Mumtaz , M. Shahroz , Mubasher , M. Shahid Khan , Mehwish Hassan , Zubair Ahmad , M. Usman , Danish Rashid , Hassan Tariq
Nanohybrids play an important role in a continuum of energy storage devices and among them cobalt ferrite (CoFe2O4) nanoparticles with multi-walled carbon nanotubes (MWCNTs) and reduced graphene oxide (rGO) nanosheets nanohybrid stands out as versatile nanomaterials due to their high performance for supercapacitor's electrodes. In this study, pure CoFe2O4 nanoparticles and their nanohybrids are successfully synthesized by one-pot hydrothermal method with subsequent ultra-sonication. The structural and morphological characterizations are carried out by X-ray diffraction and scanning electron microscopy. The electrochemical performances are investigated by cyclic voltammetry, galvanostatic charging/discharging, and electrochemical impedance spectroscopy in 1 M NaOH aqueous electrolyte. CoFe2O4/MWCNTs/rGO nanohybrids exhibited good electrochemical properties with high specific capacitance (592 F/g). More importantly, the specific capacitance of CoFe2O4/MWCNTs/rGO nanohybrid asymmetric supercapacitor device retained 89.7 % of initial capacitance after 100 cycles at scan-rate of 100 mV/s. The results suggest that the synthesized CoFe2O4/MWCNTs/rGO nanohybrids are promising candidate for supercapacitors electrodes. Moreover, the use of inexpensive carbon materials (rGO, MWCNTs) with transition metal oxides like CoFe2O4 provides a novel cost-effective tri-nanohybrid [CoFe2O4/MWCNTs/rGO] for commercial energy storage devices.
纳米杂化材料在一系列能量存储器件中发挥着重要作用，其中钴铁氧体（CoFe2O4）纳米颗粒具有多壁碳纳米管（MWCNTs）和还原氧化石墨烯（rGO）纳米片，纳米杂化材料因其在超级电容器电极上的高性能而成为多用途纳米材料。在本研究中，采用一锅水热法制备了纯CoFe2O4纳米粒子及其纳米杂化体。用x射线衍射和扫描电镜对其进行了结构和形态表征。采用循环伏安法、恒流充放电法和电化学阻抗法在1 M NaOH水溶液中研究了其电化学性能。CoFe2O4/MWCNTs/rGO纳米杂化物具有良好的电化学性能，具有较高的比电容（592 F/g）。更重要的是，CoFe2O4/MWCNTs/rGO纳米杂化非对称超级电容器器件在扫描速率为100 mV/s的条件下，经过100次循环后，其比电容保持在初始电容的89.7%。结果表明，合成的CoFe2O4/MWCNTs/rGO纳米杂化物是超级电容器电极的理想候选材料。此外，将廉价的碳材料（rGO、MWCNTs）与CoFe2O4等过渡金属氧化物结合使用，为商用储能装置提供了一种新型的具有成本效益的三纳米混合材料[CoFe2O4/MWCNTs/rGO]。
{"title":"Hybridization of cobalt ferrites nanoparticles with multiwall carbon nanotubes and reduced graphene oxide nanosheets: A path to explore new materials for supercapacitors’ electrode","authors":"M. Mumtaz , M. Shahroz , Mubasher , M. Shahid Khan , Mehwish Hassan , Zubair Ahmad , M. Usman , Danish Rashid , Hassan Tariq","doi":"10.1016/j.physe.2025.116394","DOIUrl":"10.1016/j.physe.2025.116394","url":null,"abstract":"<div><div>Nanohybrids play an important role in a continuum of energy storage devices and among them cobalt ferrite (CoFe<sub>2</sub>O<sub>4</sub>) nanoparticles with multi-walled carbon nanotubes (MWCNTs) and reduced graphene oxide (rGO) nanosheets nanohybrid stands out as versatile nanomaterials due to their high performance for supercapacitor's electrodes. In this study, pure CoFe<sub>2</sub>O<sub>4</sub> nanoparticles and their nanohybrids are successfully synthesized by one-pot hydrothermal method with subsequent ultra-sonication. The structural and morphological characterizations are carried out by X-ray diffraction and scanning electron microscopy. The electrochemical performances are investigated by cyclic voltammetry, galvanostatic charging/discharging, and electrochemical impedance spectroscopy in 1 M NaOH aqueous electrolyte. CoFe<sub>2</sub>O<sub>4</sub>/MWCNTs/rGO nanohybrids exhibited good electrochemical properties with high specific capacitance (592 F/g). More importantly, the specific capacitance of CoFe<sub>2</sub>O<sub>4</sub>/MWCNTs/rGO nanohybrid asymmetric supercapacitor device retained 89.7 % of initial capacitance after 100 cycles at scan-rate of 100 mV/s. The results suggest that the synthesized CoFe<sub>2</sub>O<sub>4</sub>/MWCNTs/rGO nanohybrids are promising candidate for supercapacitors electrodes. Moreover, the use of inexpensive carbon materials (rGO, MWCNTs) with transition metal oxides like CoFe<sub>2</sub>O<sub>4</sub> provides a novel cost-effective tri-nanohybrid [CoFe<sub>2</sub>O<sub>4</sub>/MWCNTs/rGO] for commercial energy storage devices.</div></div>","PeriodicalId":20181,"journal":{"name":"Physica E-low-dimensional Systems & Nanostructures","volume":"175 ","pages":"Article 116394"},"PeriodicalIF":2.9,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145416877","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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