Pub Date : 2025-12-22DOI: 10.1016/j.physe.2025.116452
Peng-Fei Liu , Xiao-Hong Li , Rui-Zhou Zhang , Hong-Ling Cui
The electronic properties and quantum capacitance of Pt-adsorbed Zr2CT2 (T = O, S, Se, F, Cl, Br, I) are explored by density functional theory (DFT). The most stable adsorption configurations are confirmed for all systems. Compared to pristine Zr2CO2, Pt adsorption causes the increase of band gap. Pt-Zr2CO2 exhibits an indirect bandgap semiconductor of 1.36 eV, while other systems show metallic behavior. Pt donates electrons to substrate material for Pt-Zr2CO2 and gains electrons from the substrate for other systems, especially Pt atom in Pt-Zr2CF2 gains the most electrons (0.61e). Pt-Zr2CT2 with group VII elements are anode materials in whole voltage, with the maximum surface storage charge (Q) at negative bias ranging from 69.58 to 93.05 μC/cm2 at aqueous system. Pt-Zr2CT2 (T = O, S, Se) are cathode materials in ionic/organic system. Pt-Zr2CT2 with mixed terminations are all anode materials in whole voltage.
{"title":"Structural and electronic properties, quantum capacitance of Pt-adsorbed Zr2CT2 (T = O, S, Se, F, Cl, Br, I) as supercapacitor electrode materials: First-principle predictions","authors":"Peng-Fei Liu , Xiao-Hong Li , Rui-Zhou Zhang , Hong-Ling Cui","doi":"10.1016/j.physe.2025.116452","DOIUrl":"10.1016/j.physe.2025.116452","url":null,"abstract":"<div><div>The electronic properties and quantum capacitance of Pt-adsorbed Zr<sub>2</sub>CT<sub>2</sub> (T = O, S, Se, F, Cl, Br, I) are explored by density functional theory (DFT). The most stable adsorption configurations are confirmed for all systems. Compared to pristine Zr<sub>2</sub>CO<sub>2</sub>, Pt adsorption causes the increase of band gap. Pt-Zr<sub>2</sub>CO<sub>2</sub> exhibits an indirect bandgap semiconductor of 1.36 eV, while other systems show metallic behavior. Pt donates electrons to substrate material for Pt-Zr<sub>2</sub>CO<sub>2</sub> and gains electrons from the substrate for other systems, especially Pt atom in Pt-Zr<sub>2</sub>CF<sub>2</sub> gains the most electrons (0.61e). Pt-Zr<sub>2</sub>CT<sub>2</sub> with group VII elements are anode materials in whole voltage, with the maximum surface storage charge (Q) at negative bias ranging from 69.58 to 93.05 μC/cm<sup>2</sup> at aqueous system. Pt-Zr<sub>2</sub>CT<sub>2</sub> (T = O, S, Se) are cathode materials in ionic/organic system. Pt-Zr<sub>2</sub>CT<sub>2</sub> with mixed terminations are all anode materials in whole voltage.</div></div>","PeriodicalId":20181,"journal":{"name":"Physica E-low-dimensional Systems & Nanostructures","volume":"177 ","pages":"Article 116452"},"PeriodicalIF":2.9,"publicationDate":"2025-12-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145840161","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 : 2025-12-22DOI: 10.1016/j.physe.2025.116447
Yi Peng , Fangyuan Li , Qianqian Zhu , Juexian Cao
This study comprehensively examines how point defects (vacancies and substitutional doping) affect the magnetic, and electronic characteristics of β-MoSi2N4 monolayers using first-principles calculations. The analysis reveals that β-MoSi2N4 monolayers with vacancy defects VMo or VN3Si display non-magnetic behavior, while VN1, VN2, VNSi3, and VSi introduce magnetic properties, with the magnetic moments primarily stemming from nearby atoms. Furthermore, the presence of these vacancies results in various electrical behaviors, categorizing them as semiconductors (VMo), metals (VN3Si), magnetic semiconductors (VN1), magnetic metals (VNSi3), and half-metals (VN2 and VSi). In terms of substitutional doping, the incorporation of 3d transition metal atoms (TMs) at the silicon (Si) sites of β-MoSi2N4 monolayers generally induces magnetic characteristics, with notable exceptions for Sc, Ti, and Zn. The magnetic moments associated with TM impurities from V to Cu are calculated to be 1, 2, 3, 4, 3, 2, and 0.98 μB, respectively. Remarkably, the systems doped with V, Mn, and Cu attain 100 % spin polarization and exhibit distinctive half-metallic characteristics. These findings highlight the potential to leverage point defects to modulate the properties of monolayer β-MoSi2N4, with implications for developing advanced spintronic devices.
{"title":"First-principles investigation of vacancy and doping effects on the magnetic and electronic properties of monolayer β-MoSi2N4","authors":"Yi Peng , Fangyuan Li , Qianqian Zhu , Juexian Cao","doi":"10.1016/j.physe.2025.116447","DOIUrl":"10.1016/j.physe.2025.116447","url":null,"abstract":"<div><div>This study comprehensively examines how point defects (vacancies and substitutional doping) affect the magnetic, and electronic characteristics of β-MoSi<sub>2</sub>N<sub>4</sub> monolayers using first-principles calculations. The analysis reveals that β-MoSi<sub>2</sub>N<sub>4</sub> monolayers with vacancy defects V<sub>Mo</sub> or V<sub>N3Si</sub> display non-magnetic behavior, while V<sub>N1</sub>, V<sub>N2</sub>, V<sub>NSi3</sub>, and V<sub>Si</sub> introduce magnetic properties, with the magnetic moments primarily stemming from nearby atoms. Furthermore, the presence of these vacancies results in various electrical behaviors, categorizing them as semiconductors (V<sub>Mo</sub>), metals (V<sub>N3Si</sub>), magnetic semiconductors (V<sub>N1</sub>), magnetic metals (V<sub>NSi3</sub>), and half-metals (V<sub>N2</sub> and V<sub>Si</sub>). In terms of substitutional doping, the incorporation of 3d transition metal atoms (TMs) at the silicon (Si) sites of β-MoSi<sub>2</sub>N<sub>4</sub> monolayers generally induces magnetic characteristics, with notable exceptions for Sc, Ti, and Zn. The magnetic moments associated with TM impurities from V to Cu are calculated to be 1, 2, 3, 4, 3, 2, and 0.98 μ<sub>B</sub>, respectively. Remarkably, the systems doped with V, Mn, and Cu attain 100 % spin polarization and exhibit distinctive half-metallic characteristics. These findings highlight the potential to leverage point defects to modulate the properties of monolayer β-MoSi<sub>2</sub>N<sub>4</sub>, with implications for developing advanced spintronic devices.</div></div>","PeriodicalId":20181,"journal":{"name":"Physica E-low-dimensional Systems & Nanostructures","volume":"177 ","pages":"Article 116447"},"PeriodicalIF":2.9,"publicationDate":"2025-12-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145840162","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 : 2025-12-20DOI: 10.1016/j.physe.2025.116450
S.A. Ahmadova , Samir F. Samadov , G.B. Ibragimov , I.I. Vinogradov , A.A. Sidorin , D.M. Mirzayeva , B. Mauyey , S. Sakhabayeva , P. Th Le , Matlab N. Mirzayev
Breakthrough innovations continue in the field of developing and studying new-generation materials with superior optical and mechanical properties. In this research, we investigated the defect characteristics, as well as the modification of the local bonding environment and interphase interactions, in a nanocomposite material formed by incorporating β-Ga2O3 and carbon nanotubes (CNTs) into a polyvinylidene fluoride (PVDF) matrix using positron annihilation lifetime spectroscopy (PALS) and Raman spectroscopy. Raman studies show that the D and G bands, which are indicators of the structural quality of carbon nanotubes, exhibit weak additional vibrational modes that can be associated with distortions of the β-Ga2O3 lattice and modifications of the local Ga–O coordination environment, rather than with the ideal crystalline structure. The observed peak shifts and intensity changes indicate a transition of the interphase interaction into an amorphous state, accompanied by the formation of internal structural stress and defect centers. With increasing β-Ga2O3 concentration in the composite material, the decrease in the ID/IG ratio reveals the formation of chemical bonds that strengthen the oxide layer on the surface of the carbon nanotubes. PALS analysis results clearly demonstrated that the type and size of defects strongly depend on the ratio of Ga2O3 to carbon nanotubes in the composite. In pure β-Ga2O3 structures, medium-sized vacancy clusters (τ2 = 369 ps) are present, while in carbon nanotubes (τ2 = 685 ps), and in the composite samples based on them, the τ2 component increases up to 853 ps. Analysis based on the two-state trapping model showed that the changes in the τb, kd, and τ2 – τb parameters indicate the occurrence of porosity and defect clustering processes in the composite structure depending on the CNT and β-Ga2O3 ratios. The obtained results suggest that new polymer-based composite materials with highly porous structures can serve as fundamental elements in sensor technology, optoelectronic devices, and radiation-resistant equipment.
{"title":"Investigation of defect states, free volume, and interphase interactions in β-Ga2O3/CNT polymer nanocomposites","authors":"S.A. Ahmadova , Samir F. Samadov , G.B. Ibragimov , I.I. Vinogradov , A.A. Sidorin , D.M. Mirzayeva , B. Mauyey , S. Sakhabayeva , P. Th Le , Matlab N. Mirzayev","doi":"10.1016/j.physe.2025.116450","DOIUrl":"10.1016/j.physe.2025.116450","url":null,"abstract":"<div><div>Breakthrough innovations continue in the field of developing and studying new-generation materials with superior optical and mechanical properties. In this research, we investigated the defect characteristics, as well as the modification of the local bonding environment and interphase interactions, in a nanocomposite material formed by incorporating β-Ga<sub>2</sub>O<sub>3</sub> and carbon nanotubes (CNTs) into a polyvinylidene fluoride (PVDF) matrix using positron annihilation lifetime spectroscopy (PALS) and Raman spectroscopy. Raman studies show that the D and G bands, which are indicators of the structural quality of carbon nanotubes, exhibit weak additional vibrational modes that can be associated with distortions of the β-Ga<sub>2</sub>O<sub>3</sub> lattice and modifications of the local Ga–O coordination environment, rather than with the ideal crystalline structure. The observed peak shifts and intensity changes indicate a transition of the interphase interaction into an amorphous state, accompanied by the formation of internal structural stress and defect centers. With increasing β-Ga<sub>2</sub>O<sub>3</sub> concentration in the composite material, the decrease in the ID/IG ratio reveals the formation of chemical bonds that strengthen the oxide layer on the surface of the carbon nanotubes. PALS analysis results clearly demonstrated that the type and size of defects strongly depend on the ratio of Ga<sub>2</sub>O<sub>3</sub> to carbon nanotubes in the composite. In pure β-Ga<sub>2</sub>O<sub>3</sub> structures, medium-sized vacancy clusters (τ<sub>2</sub> = 369 ps) are present, while in carbon nanotubes (τ<sub>2</sub> = 685 ps), and in the composite samples based on them, the τ<sub>2</sub> component increases up to 853 ps. Analysis based on the two-state trapping model showed that the changes in the τb, kd, and τ<sub>2</sub> – τb parameters indicate the occurrence of porosity and defect clustering processes in the composite structure depending on the CNT and β-Ga<sub>2</sub>O<sub>3</sub> ratios. The obtained results suggest that new polymer-based composite materials with highly porous structures can serve as fundamental elements in sensor technology, optoelectronic devices, and radiation-resistant equipment.</div></div>","PeriodicalId":20181,"journal":{"name":"Physica E-low-dimensional Systems & Nanostructures","volume":"177 ","pages":"Article 116450"},"PeriodicalIF":2.9,"publicationDate":"2025-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145840164","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 : 2025-12-18DOI: 10.1016/j.physe.2025.116451
Luna R.N. Oliveira , Cleber F.N. Marchiori , Carlos Moyses Araujo , Marcos G.E. da Luz
The Rashba effect is a manifestation of spin–orbit coupling in systems with structural inversion asymmetry, resulting in a spin-dependent splitting of energy bands in low-dimensional systems. This gives rise to diverse spin-dependent phenomena in semiconductor heterostructures, offering significant potential for spintronic applications. However, a comprehensive theoretical characterization remains incomplete, since most existing approaches are restricted to relatively small structures. In this work, we combine the well-established eight-band Kane model and envelope-function formalism with a recently developed Green’s function approach. The framework allows to obtain analytical expressions for the spin-dependent coherent transport in semiconductor heterostructures with an arbitrary number of cells exhibiting the Rashba effect. In addition, we propose guidelines for enhancing spin polarization and spin-miniband separation in extended semiconductor heterostructures by tuning structural inversion asymmetry. Furthermore, we find that as a geometric parameter is varied, the spin-splitting dynamics present the quantum avoided-crossing behavior. We finally show that, for suitably designed heterostructures, the polarization bands can exhibit step-like (rectangular-wave) profiles. Although our examples focus on GaAs/In-based systems, the results are expected to hold for other semiconductor materials as well.
{"title":"Spin-dependent transport in long semiconductor heterostructures with Rashba effect: A Green’s function approach","authors":"Luna R.N. Oliveira , Cleber F.N. Marchiori , Carlos Moyses Araujo , Marcos G.E. da Luz","doi":"10.1016/j.physe.2025.116451","DOIUrl":"10.1016/j.physe.2025.116451","url":null,"abstract":"<div><div>The Rashba effect is a manifestation of spin–orbit coupling in systems with structural inversion asymmetry, resulting in a spin-dependent splitting of energy bands in low-dimensional systems. This gives rise to diverse spin-dependent phenomena in semiconductor heterostructures, offering significant potential for spintronic applications. However, a comprehensive theoretical characterization remains incomplete, since most existing approaches are restricted to relatively small structures. In this work, we combine the well-established eight-band Kane model and envelope-function formalism with a recently developed Green’s function approach. The framework allows to obtain analytical expressions for the spin-dependent coherent transport in semiconductor heterostructures with an arbitrary number <span><math><mi>N</mi></math></span> of cells exhibiting the Rashba effect. In addition, we propose guidelines for enhancing spin polarization and spin-miniband separation in extended semiconductor heterostructures by tuning structural inversion asymmetry. Furthermore, we find that as a geometric parameter is varied, the spin-splitting dynamics present the quantum avoided-crossing behavior. We finally show that, for suitably designed heterostructures, the polarization bands can exhibit step-like (rectangular-wave) profiles. Although our examples focus on GaAs/In-based systems, the results are expected to hold for other semiconductor materials as well.</div></div>","PeriodicalId":20181,"journal":{"name":"Physica E-low-dimensional Systems & Nanostructures","volume":"177 ","pages":"Article 116451"},"PeriodicalIF":2.9,"publicationDate":"2025-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145840167","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 : 2025-12-17DOI: 10.1016/j.physe.2025.116449
E.J. Guzmán , O. Oubram , O. Navarro , I. Rodríguez-Vargas
We theoretically study the thermoelectric effect in phosphorene nano-sheet when the ballistic transport is modulated by gated superlattices. The gating profile consists of electrostatic barriers arranged in periodic and aperiodic Fibonacci-type sequences along the armchair direction of phosphorene. We have calculated the transmission probability and conductance by using the transfer matrix method and Landauer-Büttiker formalism, respectively. We find that the transmission miniband structure of periodic superlattices is greatly fragmented and reduced by introduction of Fibonacci-type aperiodicity. Moreover, the conductance of Fibonacci-type supelattices shows a more pronounced oscillatory trend in contrast to periodic superlattices. Such significant changes in the conductance result in enhanced thermoelectric properties at low temperatures. We find peaks of Seebeck coefficient () in orders of mV/K, with the highest peaks observed in aperiodic superlattices. Also, we obtain high values of figure of merit () in the range of and for the periodic and aperiodic superlattices, respectively. Furthermore, we find extreme values of ( mV/K) and () at energies very close to the bandgap in both (valence and conduction) bands. By analyzing the ratio of thermal and electronic conductances, we can identify the regions with optimized thermoelectric response. At 300 K, the thermoelectric response is considerably reduced () due to the thermal contribution of phonons. Our findings indicate that gated phosphorene superlattices could be the basis for high conversion efficiency thermoelectric devices.
{"title":"Ballistic transport and thermoelectric effect in gated phosphorene superlattices including Fibonacci-type aperiodicity","authors":"E.J. Guzmán , O. Oubram , O. Navarro , I. Rodríguez-Vargas","doi":"10.1016/j.physe.2025.116449","DOIUrl":"10.1016/j.physe.2025.116449","url":null,"abstract":"<div><div>We theoretically study the thermoelectric effect in phosphorene nano-sheet when the ballistic transport is modulated by gated superlattices. The gating profile consists of electrostatic barriers arranged in periodic and aperiodic Fibonacci-type sequences along the armchair direction of phosphorene. We have calculated the transmission probability and conductance by using the transfer matrix method and Landauer-Büttiker formalism, respectively. We find that the transmission miniband structure of periodic superlattices is greatly fragmented and reduced by introduction of Fibonacci-type aperiodicity. Moreover, the conductance of Fibonacci-type supelattices shows a more pronounced oscillatory trend in contrast to periodic superlattices. Such significant changes in the conductance result in enhanced thermoelectric properties at low temperatures. We find peaks of Seebeck coefficient (<span><math><mi>S</mi></math></span>) in orders of <span><math><mrow><mn>0</mn><mo>.</mo><mn>1</mn><mo>−</mo><mn>0</mn><mo>.</mo><mn>35</mn></mrow></math></span> mV/K, with the highest peaks observed in aperiodic superlattices. Also, we obtain high values of figure of merit (<span><math><mrow><mi>Z</mi><mi>T</mi></mrow></math></span>) in the range of <span><math><mrow><mn>0</mn><mo>.</mo><mn>5</mn><mo>−</mo><mn>3</mn></mrow></math></span> and <span><math><mrow><mn>2</mn><mo>−</mo><mn>10</mn></mrow></math></span> for the periodic and aperiodic superlattices, respectively. Furthermore, we find extreme values of <span><math><mi>S</mi></math></span> (<span><math><mrow><mo>></mo><mn>1</mn></mrow></math></span> mV/K) and <span><math><mrow><mi>Z</mi><mi>T</mi></mrow></math></span> (<span><math><mrow><mo>></mo><mn>10</mn></mrow></math></span>) at energies very close to the bandgap in both (valence and conduction) bands. By analyzing the ratio of thermal and electronic conductances, we can identify the regions with optimized thermoelectric response. At 300 K, the thermoelectric response is considerably reduced (<span><math><mrow><mi>Z</mi><mi>T</mi><mo>≈</mo><mn>0</mn><mo>.</mo><mn>12</mn></mrow></math></span>) due to the thermal contribution of phonons. Our findings indicate that gated phosphorene superlattices could be the basis for high conversion efficiency thermoelectric devices.</div></div>","PeriodicalId":20181,"journal":{"name":"Physica E-low-dimensional Systems & Nanostructures","volume":"177 ","pages":"Article 116449"},"PeriodicalIF":2.9,"publicationDate":"2025-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145840163","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 : 2025-12-17DOI: 10.1016/j.physe.2025.116445
A. Fakkahi , Frankbelson dos S. Azevedo , H. Azmi , M. Jaouane , J. El-Hamouchi , A. Sali , A. Ed-Dahmouny , K. El-Bakkari , R. Arraoui , A. Mazouz , M. Jaafar
This study investigates the linear and nonlinear optical properties of multilayered spherical quantum dots by focusing on electronic transitions between the , , and states. Using the Finite Element Method (FEM) within the Effective Mass Approximation (EMA), we calculate the linear, third-order nonlinear, and total optical absorption coefficients, as well as the corresponding changes in the refractive index. Our results reveal distinct spectral features associated with each type of transition, highlighting the influence of quantum confinement on the absorption and refractive index behavior. In particular, we find that the nonlinear optical response becomes increasingly significant for higher excited-state transitions, where the third-order nonlinear absorption may surpass the linear contribution in the vicinity of resonance. This behavior is observed across multiple excitation pathways, indicating that the dominance of nonlinear effects may be a general feature associated with transitions involving larger spatial extension of the electronic wavefunctions. The interplay between these transitions governs the overall optical response of the quantum dots, providing insight into their potential applications in optoelectronic and nanophotonic devices. These results suggest that multilayered spherical quantum dots can be engineered to selectively enhance nonlinear optical processes, making them promising candidates for the development of tunable, intensity-dependent photonic components.
{"title":"Study of linear and nonlinear absorption and refractive index changes in multilayered spherical quantum dots for various excited states","authors":"A. Fakkahi , Frankbelson dos S. Azevedo , H. Azmi , M. Jaouane , J. El-Hamouchi , A. Sali , A. Ed-Dahmouny , K. El-Bakkari , R. Arraoui , A. Mazouz , M. Jaafar","doi":"10.1016/j.physe.2025.116445","DOIUrl":"10.1016/j.physe.2025.116445","url":null,"abstract":"<div><div>This study investigates the linear and nonlinear optical properties of multilayered spherical quantum dots by focusing on electronic transitions between the <span><math><mrow><mi>s</mi><mo>→</mo><mi>p</mi></mrow></math></span>, <span><math><mrow><mi>p</mi><mo>→</mo><mi>d</mi></mrow></math></span>, and <span><math><mrow><mi>d</mi><mo>→</mo><mi>f</mi></mrow></math></span> states. Using the Finite Element Method (FEM) within the Effective Mass Approximation (EMA), we calculate the linear, third-order nonlinear, and total optical absorption coefficients, as well as the corresponding changes in the refractive index. Our results reveal distinct spectral features associated with each type of transition, highlighting the influence of quantum confinement on the absorption and refractive index behavior. In particular, we find that the nonlinear optical response becomes increasingly significant for higher excited-state transitions, where the third-order nonlinear absorption may surpass the linear contribution in the vicinity of resonance. This behavior is observed across multiple excitation pathways, indicating that the dominance of nonlinear effects may be a general feature associated with transitions involving larger spatial extension of the electronic wavefunctions. The interplay between these transitions governs the overall optical response of the quantum dots, providing insight into their potential applications in optoelectronic and nanophotonic devices. These results suggest that multilayered spherical quantum dots can be engineered to selectively enhance nonlinear optical processes, making them promising candidates for the development of tunable, intensity-dependent photonic components.</div></div>","PeriodicalId":20181,"journal":{"name":"Physica E-low-dimensional Systems & Nanostructures","volume":"177 ","pages":"Article 116445"},"PeriodicalIF":2.9,"publicationDate":"2025-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145840169","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}
In this study, we fabricated a broadband terahertz (THz) modulator based on an optically controlled GeSe2/Si heterojunction via magnetron sputtering and vacuum selenization. The structural and morphological properties of the fabricated GeSe2 film were characterized using XRD, Raman, SEM, and AFM. Under 532 nm laser excitation, the device exhibited a modulation depth more seven times higher than that of bare silicon. At a pump density of 1500 mW/cm2, effective modulation was achieved over a broad bandwidth of 0.2–1 THz, with a maximum modulation depth of ∼60 % at 1 THz. Systematic analysis revealed that the enhanced modulation performance originates from efficient separation and accumulation of photogenerated carriers at the heterojunction interface. Therefore, this study not only provides fundamental insights into the optoelectronic dynamics of GeSe2-based heterostructures, but also supports their potential for application in advanced THz devices, including modulators, filters, and polarizers.
{"title":"Optically controlled high-performance terahertz modulator enabled by GeSe2/Si heterojunctions","authors":"Tong Lv , Qifubo Geng , Xunjun He , Mingze Zhang , Sergey Maksimenko","doi":"10.1016/j.physe.2025.116448","DOIUrl":"10.1016/j.physe.2025.116448","url":null,"abstract":"<div><div>In this study, we fabricated a broadband terahertz (THz) modulator based on an optically controlled GeSe<sub>2</sub>/Si heterojunction via magnetron sputtering and vacuum selenization. The structural and morphological properties of the fabricated GeSe2 film were characterized using XRD, Raman, SEM, and AFM. Under 532 nm laser excitation, the device exhibited a modulation depth more seven times higher than that of bare silicon. At a pump density of 1500 mW/cm<sup>2</sup>, effective modulation was achieved over a broad bandwidth of 0.2–1 THz, with a maximum modulation depth of ∼60 % at 1 THz. Systematic analysis revealed that the enhanced modulation performance originates from efficient separation and accumulation of photogenerated carriers at the heterojunction interface. Therefore, this study not only provides fundamental insights into the optoelectronic dynamics of GeSe<sub>2</sub>-based heterostructures, but also supports their potential for application in advanced THz devices, including modulators, filters, and polarizers.</div></div>","PeriodicalId":20181,"journal":{"name":"Physica E-low-dimensional Systems & Nanostructures","volume":"177 ","pages":"Article 116448"},"PeriodicalIF":2.9,"publicationDate":"2025-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145787220","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 : 2025-12-12DOI: 10.1016/j.physe.2025.116443
E.A. Vardanyan , G.A. Mantashian , N. Zeiri , P.A. Mantashyan , S. Thomas , D.B. Hayrapetyan
Boomerang-shaped semiconductor quantum nanostructures, also referred to as nanoboomerangs, offer unique optical and electronic properties due to their asymmetrical geometry, which enhances the spatial separation of charge carriers. This study investigates the influence of external electric fields on the excitonic states, dipole moments, and absorption spectra of these structures. Using the finite element method, we solve the Schrödinger equation to obtain the energy spectra and wave functions, which are then applied in a variational approach to model excitonic properties. The results reveal that the application of an electric field induces significant redshifts in the absorption spectrum due to the Stark effect, alongside variations in oscillator strengths. Strong overlap between wave functions of the same parity results in enhanced transitions, while mixed-parity transitions are amplified by the field-induced redistribution of charge carrier probability densities. The calculated dipole moments demonstrate field-dependent saturation behavior, reaching values as high as 725 Debye, attributable to the unique geometry of the boomerang-shaped nanostructures.
{"title":"Enhanced dipole moment and absorption spectrum in CdSe nanoboomerang under external electric field","authors":"E.A. Vardanyan , G.A. Mantashian , N. Zeiri , P.A. Mantashyan , S. Thomas , D.B. Hayrapetyan","doi":"10.1016/j.physe.2025.116443","DOIUrl":"10.1016/j.physe.2025.116443","url":null,"abstract":"<div><div>Boomerang-shaped semiconductor quantum nanostructures, also referred to as nanoboomerangs, offer unique optical and electronic properties due to their asymmetrical geometry, which enhances the spatial separation of charge carriers. This study investigates the influence of external electric fields on the excitonic states, dipole moments, and absorption spectra of these structures. Using the finite element method, we solve the Schrödinger equation to obtain the energy spectra and wave functions, which are then applied in a variational approach to model excitonic properties. The results reveal that the application of an electric field induces significant redshifts in the absorption spectrum due to the Stark effect, alongside variations in oscillator strengths. Strong overlap between wave functions of the same parity results in enhanced transitions, while mixed-parity transitions are amplified by the field-induced redistribution of charge carrier probability densities. The calculated dipole moments demonstrate field-dependent saturation behavior, reaching values as high as 725 Debye, attributable to the unique geometry of the boomerang-shaped nanostructures.</div></div>","PeriodicalId":20181,"journal":{"name":"Physica E-low-dimensional Systems & Nanostructures","volume":"177 ","pages":"Article 116443"},"PeriodicalIF":2.9,"publicationDate":"2025-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145787202","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 : 2025-12-10DOI: 10.1016/j.physe.2025.116446
A.M. Hassanien
The structural, morphological, and optical spectroscopic properties of hexadecafluoro zinc phthalocyanine (ZnPcF16) are promising investigations that can be useful in optoelectronic applications. The nature of the crystallographic structure and morphology characteristics were explored by field emission scanning electron microscopy (FESEM), and X-ray diffraction (XRD) investigations. To determine some crucial optical properties of the ZnPcF16 dye in solution, such as absorption peaks position, photoluminescence emission peaks position, oscillator strengths () and electric dipole strength (), spectrum behavior of the absorbance, fluorescent properties, and molar absorption coefficient spectra of ZnPcF16 in Dimethyl Sulfoxide (DMSO) were examined. Absorbance spectra, transmittance, reflectance, and photoluminescence (PL) of ZnPcF16 thin films before and after annealing at 373 K & 473 K in an air ambient for 2 h were used to deduce the optical band transitions, emission peaks position, and dispersion behaviour. This study demonstrates that the ZnPcF16 organic compound is characterized by good thermal stability, appropriate optical band gap, and dielectric properties, which offer potential uses as an active photonic organic material and should be properly addressed in the device design of optoelectronic technological devices.
{"title":"Optoelectronic applications of hexadecafluoro zinc phthalocyanine (ZnPcF16) thin films: structural, morphological, and optical characteristics","authors":"A.M. Hassanien","doi":"10.1016/j.physe.2025.116446","DOIUrl":"10.1016/j.physe.2025.116446","url":null,"abstract":"<div><div>The structural, morphological, and optical spectroscopic properties of hexadecafluoro zinc phthalocyanine <strong>(ZnPcF16)</strong> are promising investigations that can be useful in optoelectronic applications. The nature of the crystallographic structure and morphology characteristics were explored by field emission scanning electron microscopy (FESEM), and X-ray diffraction (XRD) investigations. To determine some crucial optical properties of the <strong>ZnPcF16</strong> dye in solution, such as absorption peaks position, photoluminescence emission peaks position, oscillator strengths (<span><math><mrow><mi>f</mi></mrow></math></span>) and electric dipole strength (<span><math><mrow><msup><mi>q</mi><mn>2</mn></msup></mrow></math></span>), spectrum behavior of the absorbance, fluorescent properties, and molar absorption coefficient spectra of <strong>ZnPcF16</strong> in Dimethyl Sulfoxide (DMSO) were examined. Absorbance spectra, transmittance, reflectance, and photoluminescence (PL) of <strong>ZnPcF16</strong> thin films before and after annealing at 373 K & 473 K in an air ambient for 2 h were used to deduce the optical band transitions, emission peaks position, and dispersion behaviour. This study demonstrates that the <strong>ZnPcF16</strong> organic compound is characterized by good thermal stability, appropriate optical band gap, and dielectric properties, which offer potential uses as an active photonic organic material and should be properly addressed in the device design of optoelectronic technological devices.</div></div>","PeriodicalId":20181,"journal":{"name":"Physica E-low-dimensional Systems & Nanostructures","volume":"177 ","pages":"Article 116446"},"PeriodicalIF":2.9,"publicationDate":"2025-12-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145787221","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 : 2025-12-10DOI: 10.1016/j.physe.2025.116441
Jiansheng Hu , Yingliang Chen , Zhaoming Fu , Peizhi Yang , Xiaobo Feng
We present a comprehensive theoretical study on the stacking-dependent photoconductivity of bilayer silicene under external electric and exchange fields, with a focus on the critical role of spin-orbit coupling (SOC). Using the Kane-Mele tight-binding model combined with Kubo formalism, we systematically investigate the interband and intraband optical conductivity across infrared to visible spectral ranges for both AA- and AB-stacked configurations. The calculations reveal that the SOC induces distinct bandgap hierarchies (16 meV for AA stacking vs 7.8 meV for AB stacking) and triggers a redshift in infrared photoconductivity, with AB stacking exhibiting stronger SOC sensitivity. AA stacking maintains stable visible-range peaks while AB stacking shows dual peak modulation and far-infrared enhancement above V = 0.15 eV. Exchange fields generate spin-split van Hove singularities, with AB stacking exhibiting accelerated conductivity growth above M = 0.05 eV. The sign reversal of imaginary conductivity at ℏω = 2 eV enables plasmonic mode selection. These findings establish a unified framework for field-controlled optoelectronic response in bilayer silicene, providing design principles for tunable photodetectors and quantum spin devices.
{"title":"Stacking-dependent photoconductivity in bilayer silicene: external-field modulation via spin-orbit coupling","authors":"Jiansheng Hu , Yingliang Chen , Zhaoming Fu , Peizhi Yang , Xiaobo Feng","doi":"10.1016/j.physe.2025.116441","DOIUrl":"10.1016/j.physe.2025.116441","url":null,"abstract":"<div><div>We present a comprehensive theoretical study on the stacking-dependent photoconductivity of bilayer silicene under external electric and exchange fields, with a focus on the critical role of spin-orbit coupling (SOC). Using the Kane-Mele tight-binding model combined with Kubo formalism, we systematically investigate the interband and intraband optical conductivity across infrared to visible spectral ranges for both AA- and AB-stacked configurations. The calculations reveal that the SOC induces distinct bandgap hierarchies (16 meV for AA stacking <em>vs</em> 7.8 meV for AB stacking) and triggers a redshift in infrared photoconductivity, with AB stacking exhibiting stronger SOC sensitivity. AA stacking maintains stable visible-range peaks while AB stacking shows dual peak modulation and far-infrared enhancement above <em>V</em> = 0.15 eV. Exchange fields generate spin-split van Hove singularities, with AB stacking exhibiting accelerated conductivity growth above <em>M</em> = 0.05 eV. The sign reversal of imaginary conductivity at ℏ<em>ω</em> = 2 eV enables plasmonic mode selection. These findings establish a unified framework for field-controlled optoelectronic response in bilayer silicene, providing design principles for tunable photodetectors and quantum spin devices.</div></div>","PeriodicalId":20181,"journal":{"name":"Physica E-low-dimensional Systems & Nanostructures","volume":"177 ","pages":"Article 116441"},"PeriodicalIF":2.9,"publicationDate":"2025-12-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145737369","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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