Subhashree Das, Swikruti Supriya, D. Alagarasan, R. Ganesan, R. Naik
The 2D Bi2Te3 narrow bandgap semiconductor is an outstanding applicant for optoelectronics and thermoelectric devices. The doping of Se into Bi2Te3 makes metal-double chalcogenide more important. In the current investigation, the Se diffusion into the Bi2Te3 film by thermal annealing at different temperatures is probed through a temperature-dependent Raman study along with other characterizations. Upon annealing, the Se/Bi2Te3 films of ∼810 nm thickness resulted in significant changes to their structural, electronic, and optical behavior. The existence of a rhombohedral Bi2Te3 phase was confirmed by structural investigation. The improvement in crystallinity and decrease in lattice strain modified the optical behavior of the films. The morphology analysis showed a slight aggregation at the higher annealed stage. The uniform and homogeneous dispersal and the composition of elements in the film were verified through surface mapping and compositional analysis. The optical investigation revealed a drop in absorbance with increased transmittance. The direct optical bandgap increased from 0.53 ± 0.002 to 0.77 ± 0.002 eV, showing a blue shift. The non-linear refractive index decreased from 3.72 to 1.85 × 10−16 m2/W upon annealing. The temperature-dependent Raman analysis demonstrated a thermally induced significant vibrational change in the material with specific additional peaks at higher annealing. Such findings can be employed as a phase change material at very high temperatures. The obtained findings are very useful for optoelectronic applications. Surface wettability shows a reduction in hydrophilicity, thus inching toward a hydrophobic one with an increase in annealing temperatures. The enhancement in the photocurrent with the increment in the annealing temperature is more suitable for photovoltaic applications.
{"title":"Investigating the temperature-dependent Raman spectroscopy of Se/Bi2Te3 thin films and its enhanced photoresponse for optoelectronic applications","authors":"Subhashree Das, Swikruti Supriya, D. Alagarasan, R. Ganesan, R. Naik","doi":"10.1063/5.0216795","DOIUrl":"https://doi.org/10.1063/5.0216795","url":null,"abstract":"The 2D Bi2Te3 narrow bandgap semiconductor is an outstanding applicant for optoelectronics and thermoelectric devices. The doping of Se into Bi2Te3 makes metal-double chalcogenide more important. In the current investigation, the Se diffusion into the Bi2Te3 film by thermal annealing at different temperatures is probed through a temperature-dependent Raman study along with other characterizations. Upon annealing, the Se/Bi2Te3 films of ∼810 nm thickness resulted in significant changes to their structural, electronic, and optical behavior. The existence of a rhombohedral Bi2Te3 phase was confirmed by structural investigation. The improvement in crystallinity and decrease in lattice strain modified the optical behavior of the films. The morphology analysis showed a slight aggregation at the higher annealed stage. The uniform and homogeneous dispersal and the composition of elements in the film were verified through surface mapping and compositional analysis. The optical investigation revealed a drop in absorbance with increased transmittance. The direct optical bandgap increased from 0.53 ± 0.002 to 0.77 ± 0.002 eV, showing a blue shift. The non-linear refractive index decreased from 3.72 to 1.85 × 10−16 m2/W upon annealing. The temperature-dependent Raman analysis demonstrated a thermally induced significant vibrational change in the material with specific additional peaks at higher annealing. Such findings can be employed as a phase change material at very high temperatures. The obtained findings are very useful for optoelectronic applications. Surface wettability shows a reduction in hydrophilicity, thus inching toward a hydrophobic one with an increase in annealing temperatures. The enhancement in the photocurrent with the increment in the annealing temperature is more suitable for photovoltaic applications.","PeriodicalId":502933,"journal":{"name":"Journal of Applied Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141927600","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}
O. Steuer, M. Michailow, R. Hübner, K. Pyszniak, M. Turek, U. Kentsch, F. Ganss, M. M. Khan, L. Rebohle, S. Zhou, J. Knoch, M. Helm, G. Cuniberti, Y. M. Georgiev, S. Prucnal
For many years, Si1−yGey alloys have been applied in the semiconductor industry due to the ability to adjust the performance of Si-based nanoelectronic devices. Following this alloying approach of group-IV semiconductors, adding tin (Sn) into the alloy appears as the obvious next step, which leads to additional possibilities for tailoring the material properties. Adding Sn enables effective bandgap and strain engineering and can improve the carrier mobilities, which makes Si1−x−yGeySnx alloys promising candidates for future opto- and nanoelectronics applications. The bottom-up approach for epitaxial growth of Si1−x−yGeySnx, e.g., by chemical vapor deposition and molecular beam epitaxy, allows tuning the material properties in the growth direction only; the realization of local material modifications to generate lateral heterostructures with such a bottom-up approach is extremely elaborate, since it would require the use of lithography, etching, and either selective epitaxy or epitaxy and chemical–mechanical polishing, giving rise to interface issues, non-planar substrates, etc. This article shows the possibility of fabricating Si1−x−yGeySnx alloys by Sn ion beam implantation into Si1−yGey layers followed by millisecond-range flash lamp annealing (FLA). The materials are investigated by Rutherford backscattering spectrometry, micro-Raman spectroscopy, x-ray diffraction, and transmission electron microscopy. The fabrication approach was adapted to ultra-thin Si1−yGey layers on silicon-on-insulator substrates. The results show the fabrication of single-crystalline Si1−x−yGeySnx with up to 2.3 at. % incorporated Sn without any indication of Sn segregation after recrystallization via FLA. Finally, we exhibit the possibility of implanting Sn locally in ultra-thin Si1−yGey films by masking unstructured regions on the chip, thus demonstrating the realization of vertical as well as lateral Si1−x−yGeySnx heterostructures by Sn ion implantation and flash lamp annealing.
{"title":"Si1−x−yGeySnx alloy formation by Sn ion implantation and flash lamp annealing","authors":"O. Steuer, M. Michailow, R. Hübner, K. Pyszniak, M. Turek, U. Kentsch, F. Ganss, M. M. Khan, L. Rebohle, S. Zhou, J. Knoch, M. Helm, G. Cuniberti, Y. M. Georgiev, S. Prucnal","doi":"10.1063/5.0220639","DOIUrl":"https://doi.org/10.1063/5.0220639","url":null,"abstract":"For many years, Si1−yGey alloys have been applied in the semiconductor industry due to the ability to adjust the performance of Si-based nanoelectronic devices. Following this alloying approach of group-IV semiconductors, adding tin (Sn) into the alloy appears as the obvious next step, which leads to additional possibilities for tailoring the material properties. Adding Sn enables effective bandgap and strain engineering and can improve the carrier mobilities, which makes Si1−x−yGeySnx alloys promising candidates for future opto- and nanoelectronics applications. The bottom-up approach for epitaxial growth of Si1−x−yGeySnx, e.g., by chemical vapor deposition and molecular beam epitaxy, allows tuning the material properties in the growth direction only; the realization of local material modifications to generate lateral heterostructures with such a bottom-up approach is extremely elaborate, since it would require the use of lithography, etching, and either selective epitaxy or epitaxy and chemical–mechanical polishing, giving rise to interface issues, non-planar substrates, etc. This article shows the possibility of fabricating Si1−x−yGeySnx alloys by Sn ion beam implantation into Si1−yGey layers followed by millisecond-range flash lamp annealing (FLA). The materials are investigated by Rutherford backscattering spectrometry, micro-Raman spectroscopy, x-ray diffraction, and transmission electron microscopy. The fabrication approach was adapted to ultra-thin Si1−yGey layers on silicon-on-insulator substrates. The results show the fabrication of single-crystalline Si1−x−yGeySnx with up to 2.3 at. % incorporated Sn without any indication of Sn segregation after recrystallization via FLA. Finally, we exhibit the possibility of implanting Sn locally in ultra-thin Si1−yGey films by masking unstructured regions on the chip, thus demonstrating the realization of vertical as well as lateral Si1−x−yGeySnx heterostructures by Sn ion implantation and flash lamp annealing.","PeriodicalId":502933,"journal":{"name":"Journal of Applied Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141929664","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}
Ming Jiang, Wang-Jian Liu, Yan Zhou, Xu-Sheng Liu, Chandra Veer Singh
The degradation of β-Ga2O3-based devices’ performance may occur when they are bombarded by charged particles in aerospace, astronomy, and nuclear-related applications. It is significant to explore the influence of irradiation on the microstructure of β-Ga2O3 and to reveal the internal relationship between the damage mechanisms and physical characteristics. Thus, we explored the low-energy recoil events of β-Ga2O3 based on the first-principles calculations in the present study. The threshold displacement energies (Eds) significantly depended on the recoil directions and the primary knock-on atoms. Eds of Ga atoms are generally larger than those of O atoms, indicating that the displacements of O atoms dominate under electron irradiation. In the neutral state, the formation energy of VO(I) is lower than that of VO(II) and VO(III), while in the +2 charge state, the case is a reversal. The formation energy of Oint(II) defect is high, and thus its equilibrium concentration is low, indicating that the Oint(II) defect is unlikely to be relevant for the thermal-mechanical properties of β-Ga2O3. The charged VO and Oint defects deteriorate the ability to resist external compression more profoundly, while defective β-Ga2O3 with lower Young's modulus is expected to possess higher elastic compliance than pristine β-Ga2O3. The lattice thermal conductivity of β-Ga2O3 decreases with increasing temperature and the charged point defects generally result in the decreasing lattice thermal conductivity more profoundly than neutral point defects. The presented results provide underlying mechanisms for defect generation in β-Ga2O3 and advance the fundamental understanding of the radiation resistances of semiconductor materials.
{"title":"A first-principles study of low-energy radiation responses of β-Ga2O3","authors":"Ming Jiang, Wang-Jian Liu, Yan Zhou, Xu-Sheng Liu, Chandra Veer Singh","doi":"10.1063/5.0203161","DOIUrl":"https://doi.org/10.1063/5.0203161","url":null,"abstract":"The degradation of β-Ga2O3-based devices’ performance may occur when they are bombarded by charged particles in aerospace, astronomy, and nuclear-related applications. It is significant to explore the influence of irradiation on the microstructure of β-Ga2O3 and to reveal the internal relationship between the damage mechanisms and physical characteristics. Thus, we explored the low-energy recoil events of β-Ga2O3 based on the first-principles calculations in the present study. The threshold displacement energies (Eds) significantly depended on the recoil directions and the primary knock-on atoms. Eds of Ga atoms are generally larger than those of O atoms, indicating that the displacements of O atoms dominate under electron irradiation. In the neutral state, the formation energy of VO(I) is lower than that of VO(II) and VO(III), while in the +2 charge state, the case is a reversal. The formation energy of Oint(II) defect is high, and thus its equilibrium concentration is low, indicating that the Oint(II) defect is unlikely to be relevant for the thermal-mechanical properties of β-Ga2O3. The charged VO and Oint defects deteriorate the ability to resist external compression more profoundly, while defective β-Ga2O3 with lower Young's modulus is expected to possess higher elastic compliance than pristine β-Ga2O3. The lattice thermal conductivity of β-Ga2O3 decreases with increasing temperature and the charged point defects generally result in the decreasing lattice thermal conductivity more profoundly than neutral point defects. The presented results provide underlying mechanisms for defect generation in β-Ga2O3 and advance the fundamental understanding of the radiation resistances of semiconductor materials.","PeriodicalId":502933,"journal":{"name":"Journal of Applied Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141927440","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}
Cheul Hyun Yoon, Gyeong Min Seo, Seok Hyun Yoon, Byoung Don Kong
We investigate the potential of nanovacuum devices utilizing graphene edges as field emitters, with their work function modulated by a nearby gate on the graphene surface. Unlike metals, the semi-metallic nature of graphene enables modulation of the Fermi level and work function via the surface field. This modulation alters the potential barrier for field emission. Our simulation study reveals that device operation critically depends on two screening factors—horizontal and vertical. Horizontally, work function modulation occurs when the emitter edge is within the critical screening length from the gate edge. Vertically, the effectiveness of work function modulation diminishes beyond the second layer of multi-layer graphene due to surface field screening by the first layer. Our simulations demonstrate that maintaining the vacuum channel on tens of nanometer scale enables transistor-like operation of the device, with remarkably high cut-off frequencies and maximum oscillation frequencies ranging from 0.45 to 0.71 and 32.9 to 40.5 THz, respectively, under source–drain bias from 90 to 100 V.
{"title":"Field emission control by work function modulation in graphene edge cathodes","authors":"Cheul Hyun Yoon, Gyeong Min Seo, Seok Hyun Yoon, Byoung Don Kong","doi":"10.1063/5.0215449","DOIUrl":"https://doi.org/10.1063/5.0215449","url":null,"abstract":"We investigate the potential of nanovacuum devices utilizing graphene edges as field emitters, with their work function modulated by a nearby gate on the graphene surface. Unlike metals, the semi-metallic nature of graphene enables modulation of the Fermi level and work function via the surface field. This modulation alters the potential barrier for field emission. Our simulation study reveals that device operation critically depends on two screening factors—horizontal and vertical. Horizontally, work function modulation occurs when the emitter edge is within the critical screening length from the gate edge. Vertically, the effectiveness of work function modulation diminishes beyond the second layer of multi-layer graphene due to surface field screening by the first layer. Our simulations demonstrate that maintaining the vacuum channel on tens of nanometer scale enables transistor-like operation of the device, with remarkably high cut-off frequencies and maximum oscillation frequencies ranging from 0.45 to 0.71 and 32.9 to 40.5 THz, respectively, under source–drain bias from 90 to 100 V.","PeriodicalId":502933,"journal":{"name":"Journal of Applied Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141928228","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}
The century-long problem of conversion of plastic work to heat is controversial and challenging. In this work, 2D and 3D molecular simulations of crystal Cu are carried out to study the micro-mechanism of plastic work converting to heat. The results show that heat generation comes along with lattice restoration, transferring part of potential energy of defects, i.e., stored energy of cold work (SECW), to kinetic energy. As a result, specific crystallographic defects generate amounts of heat corresponding to variations of their SECW. If the change of microstructure and temperature are only detected at the surface of the system, the time lag of heat generation will be observed. The simulation results are indispensable accompaniments of experimental research, unveiling how plastic heat is affected by the type, propagation path, and density of defects, providing nano-scale explanations for the time lag of temperature rising in experiments.
塑性功转化为热量这一世纪难题具有争议性和挑战性。在这项工作中，我们对晶体 Cu 进行了二维和三维分子模拟，以研究塑性功转化为热量的微观机制。结果表明，热量的产生伴随着晶格的恢复，将缺陷的部分势能，即冷功储存能（SECW）转移为动能。因此，特定晶体学缺陷产生的热量与其 SECW 的变化量相对应。如果只在系统表面检测到微观结构和温度的变化，则会观察到热量产生的时滞。模拟结果是实验研究不可或缺的辅助工具，它揭示了塑性热如何受缺陷类型、传播路径和密度的影响，为实验中温度上升的时滞提供了纳米级解释。
{"title":"Conversion of plastic work to heat in crystal Cu: A microscopic view by molecular simulations","authors":"Ronghao Shi, Pan Xiao, Rong Yang, Jun Wang","doi":"10.1063/5.0213106","DOIUrl":"https://doi.org/10.1063/5.0213106","url":null,"abstract":"The century-long problem of conversion of plastic work to heat is controversial and challenging. In this work, 2D and 3D molecular simulations of crystal Cu are carried out to study the micro-mechanism of plastic work converting to heat. The results show that heat generation comes along with lattice restoration, transferring part of potential energy of defects, i.e., stored energy of cold work (SECW), to kinetic energy. As a result, specific crystallographic defects generate amounts of heat corresponding to variations of their SECW. If the change of microstructure and temperature are only detected at the surface of the system, the time lag of heat generation will be observed. The simulation results are indispensable accompaniments of experimental research, unveiling how plastic heat is affected by the type, propagation path, and density of defects, providing nano-scale explanations for the time lag of temperature rising in experiments.","PeriodicalId":502933,"journal":{"name":"Journal of Applied Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141929391","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}
Monolayer indium selenide (InSe), a two-dimensional material, exhibits exceptional electronic and optical properties that can be significantly modulated via strain engineering. This study employed density functional theory to examine the structural and vibrational properties of monolayer InSe under varying biaxial strains. Phonon dispersion analysis confirmed the stability of monolayer InSe, as indicated by the absence of imaginary frequencies. The study extensively detailed how Raman and infrared spectra adjust under strain, showing shifts in peak positions and variations in intensity that reflect changes in lattice symmetry and electronic structures. Specific findings include the stiffening of the A′1 mode and the increased intensity of E″ and E′ modes under strain, suggesting enhanced polarizability and asymmetric vibrations. Moreover, the Raman intensity for the E′ mode at 167.3 cm−1 increased under both tensile and compressive strain due to enhanced polarizability and symmetry disruption, while the IR intensity for the A″2 mode at 192.1 cm−1 decreased, likely from diminished dipole moment changes. In contrast, the low-frequency modes, such as E″ at 36.8 cm−1, demonstrated insensitivity to strain, implying a minimal impact on heavier atoms within these modes. Overall, this study highlights the sensitivity of vibrational modes to strain-induced changes, providing valuable insights into the behavior of monolayer InSe under mechanical stress.
{"title":"Strain-induced variations in the Raman and infrared spectra of monolayer InSe: A first-principles study","authors":"Xiangyu Zeng, Yutong Chen, Yuanfei Jiang, Laizhi Sui, Anmin Chen, Mingxing Jin","doi":"10.1063/5.0221262","DOIUrl":"https://doi.org/10.1063/5.0221262","url":null,"abstract":"Monolayer indium selenide (InSe), a two-dimensional material, exhibits exceptional electronic and optical properties that can be significantly modulated via strain engineering. This study employed density functional theory to examine the structural and vibrational properties of monolayer InSe under varying biaxial strains. Phonon dispersion analysis confirmed the stability of monolayer InSe, as indicated by the absence of imaginary frequencies. The study extensively detailed how Raman and infrared spectra adjust under strain, showing shifts in peak positions and variations in intensity that reflect changes in lattice symmetry and electronic structures. Specific findings include the stiffening of the A′1 mode and the increased intensity of E″ and E′ modes under strain, suggesting enhanced polarizability and asymmetric vibrations. Moreover, the Raman intensity for the E′ mode at 167.3 cm−1 increased under both tensile and compressive strain due to enhanced polarizability and symmetry disruption, while the IR intensity for the A″2 mode at 192.1 cm−1 decreased, likely from diminished dipole moment changes. In contrast, the low-frequency modes, such as E″ at 36.8 cm−1, demonstrated insensitivity to strain, implying a minimal impact on heavier atoms within these modes. Overall, this study highlights the sensitivity of vibrational modes to strain-induced changes, providing valuable insights into the behavior of monolayer InSe under mechanical stress.","PeriodicalId":502933,"journal":{"name":"Journal of Applied Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141928818","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}
S. Gan, J. Chew, Kok Bin Ng, L. Tey, Wu Yi Chong, B. T. Goh, C. Lai, Duk-Yong Choi, Steve Madden, H. Ahmad
Ge2Sb2Se4Te1 (GSST) exhibits unprecedented broadband transparency over the infrared wavelength range and has emerged as a promising functional material in photonic applications that operate in the optical fiber telecommunication wavelength band. In this work, GSST and graphene oxide (GO) are integrated into an optical fiber link to achieve all-fiber non-volatile multilevel photonic memory. The GSST and GO (GSST-GO) duo-layer hybrid structure is sandwiched between two optical fiber ferrules, where the GO acts as a localized heat source to initiate the phase transition of GSST upon optical excitation. The GSST-GO-coated fiber exhibits a low insertion loss of 0.8 dB and a maximum readout contrast of about 32%, with at least five distinguished memory states. The response time of the device is measured in the range between 2.5 and 9.5 μs. This work serves as a proof of concept on implementing the GSST-GO duo-layer hybrid structure in optical fiber platform to realize all-fiber non-volatile multi-bit channel control or data storage.
{"title":"Single-mode fiber multi-level all-optical switching using GSST-graphene oxide hybrid thin film structure","authors":"S. Gan, J. Chew, Kok Bin Ng, L. Tey, Wu Yi Chong, B. T. Goh, C. Lai, Duk-Yong Choi, Steve Madden, H. Ahmad","doi":"10.1063/5.0211865","DOIUrl":"https://doi.org/10.1063/5.0211865","url":null,"abstract":"Ge2Sb2Se4Te1 (GSST) exhibits unprecedented broadband transparency over the infrared wavelength range and has emerged as a promising functional material in photonic applications that operate in the optical fiber telecommunication wavelength band. In this work, GSST and graphene oxide (GO) are integrated into an optical fiber link to achieve all-fiber non-volatile multilevel photonic memory. The GSST and GO (GSST-GO) duo-layer hybrid structure is sandwiched between two optical fiber ferrules, where the GO acts as a localized heat source to initiate the phase transition of GSST upon optical excitation. The GSST-GO-coated fiber exhibits a low insertion loss of 0.8 dB and a maximum readout contrast of about 32%, with at least five distinguished memory states. The response time of the device is measured in the range between 2.5 and 9.5 μs. This work serves as a proof of concept on implementing the GSST-GO duo-layer hybrid structure in optical fiber platform to realize all-fiber non-volatile multi-bit channel control or data storage.","PeriodicalId":502933,"journal":{"name":"Journal of Applied Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141925928","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}
Fredy Mamani Gonzalo, Victor José Ramirez Rivera, Maurício Jeomar Piotrowski, Efracio Mamani Flores
The enhancement of thermoelectric properties in CoSb3 through atom substitution and hydrostatic pressure application is a promising avenue. Herein, we conducted a comprehensive theoretical investigation into the structural, electronic, and thermoelectric characteristics of CoSb3−xAx (A = Ge, Se, Te; x = 0.125, 0.250) using density functional theory coupled with Boltzmann transport theory. By subjecting the system to pressures ranging from 0 to 20 GPa and substituting Sb atoms, we evaluated the enthalpy of formation to predict stability, with CoSb2.875Te0.125 exhibiting superior stability under 20 GPa. The bandgap of doped compounds is direct, ranging from 0.33 to 0.56 eV along the Γ point, and was calculated to elucidate electronic properties. Additionally, employing the Slack model, we computed lattice thermal conductivity based on elastic constants to provide a comprehensive analysis of thermoelectric efficiency. Remarkably, our study not only highlights the effect of hydrostatic pressure on structural and electronic properties but also reveals a beneficial impact on increasing ZT values to 2.77 for CoSb2.750Ge0.250 at 800 K and 20 GPa, indicating predominantly p-type behavior.
{"title":"First-principles investigation of pressure-induced structural, electronic, and thermoelectric properties in CoSb3−xAx compounds (A = Ge, Se, Te)","authors":"Fredy Mamani Gonzalo, Victor José Ramirez Rivera, Maurício Jeomar Piotrowski, Efracio Mamani Flores","doi":"10.1063/5.0221587","DOIUrl":"https://doi.org/10.1063/5.0221587","url":null,"abstract":"The enhancement of thermoelectric properties in CoSb3 through atom substitution and hydrostatic pressure application is a promising avenue. Herein, we conducted a comprehensive theoretical investigation into the structural, electronic, and thermoelectric characteristics of CoSb3−xAx (A = Ge, Se, Te; x = 0.125, 0.250) using density functional theory coupled with Boltzmann transport theory. By subjecting the system to pressures ranging from 0 to 20 GPa and substituting Sb atoms, we evaluated the enthalpy of formation to predict stability, with CoSb2.875Te0.125 exhibiting superior stability under 20 GPa. The bandgap of doped compounds is direct, ranging from 0.33 to 0.56 eV along the Γ point, and was calculated to elucidate electronic properties. Additionally, employing the Slack model, we computed lattice thermal conductivity based on elastic constants to provide a comprehensive analysis of thermoelectric efficiency. Remarkably, our study not only highlights the effect of hydrostatic pressure on structural and electronic properties but also reveals a beneficial impact on increasing ZT values to 2.77 for CoSb2.750Ge0.250 at 800 K and 20 GPa, indicating predominantly p-type behavior.","PeriodicalId":502933,"journal":{"name":"Journal of Applied Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141927840","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}
Mingliang Yang, Xinchen Jiang, Alexander S. Shalin, Lei Gao
The investigation on the temporal dynamics of graphene-wrapped core–shell nanoparticles under the illumination of a Gaussian impulse have been carried out. By altering the graphene layers and the aspect ratio of the core–shell structure, we can adjust the resonant modes into typical cases in regime of terahertz. Accordingly, different scenarios for the temporal evolution are detected, which include two kinds of ultrafast oscillation with exponential decay tendency, pure exponential decay, and Gaussian shape, when the pulse duration of the incident pulse is much shorter than, similar to, and much longer than the localized surface plasmon lifetime. To one's interest, when the coupling between two resonant modes exists, one predicts the long-periodic oscillation, whose period is just the difference between the frequencies of the resonant modes. Hence, the intrinsic properties of the ultrafast oscillation can be hardly influenced by the input signals. Further quantitative calculation demonstrate that the periods of the ultrafast oscillations can be tuned by different physical mechanisms, which are, respectively, based on the self-interacting correction of a single resonance and the strong coupling between the resonant modes in frequency domain. Our results may be applicable in the fields of optical sensors, optical information processing, and other nanophotonic devices.
{"title":"Tunable temporal dynamics of dipole response in graphene-wrapped core–shell nanoparticles","authors":"Mingliang Yang, Xinchen Jiang, Alexander S. Shalin, Lei Gao","doi":"10.1063/5.0208639","DOIUrl":"https://doi.org/10.1063/5.0208639","url":null,"abstract":"The investigation on the temporal dynamics of graphene-wrapped core–shell nanoparticles under the illumination of a Gaussian impulse have been carried out. By altering the graphene layers and the aspect ratio of the core–shell structure, we can adjust the resonant modes into typical cases in regime of terahertz. Accordingly, different scenarios for the temporal evolution are detected, which include two kinds of ultrafast oscillation with exponential decay tendency, pure exponential decay, and Gaussian shape, when the pulse duration of the incident pulse is much shorter than, similar to, and much longer than the localized surface plasmon lifetime. To one's interest, when the coupling between two resonant modes exists, one predicts the long-periodic oscillation, whose period is just the difference between the frequencies of the resonant modes. Hence, the intrinsic properties of the ultrafast oscillation can be hardly influenced by the input signals. Further quantitative calculation demonstrate that the periods of the ultrafast oscillations can be tuned by different physical mechanisms, which are, respectively, based on the self-interacting correction of a single resonance and the strong coupling between the resonant modes in frequency domain. Our results may be applicable in the fields of optical sensors, optical information processing, and other nanophotonic devices.","PeriodicalId":502933,"journal":{"name":"Journal of Applied Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140965618","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}
A power generator comprising a thermoelectric device (TED) and a phase change material (PCM) allows energy harvesting from ambient temperature variations, which exist ubiquitously; thus, such a device has received considerable attention as an energy harvester that can operate at any location. We developed a model for estimating the characteristics of a power generator in ambient air, whose temperature is forcibly changed between two temperature values, such as when an air conditioner is turned on and off. We calculated the influence of latent heat and thermal conductivity of the PCM on the characteristics of power generators with various thermal resistances between the TED/PCM interface and ambient air. Latent heat and thermal conductivity of the PCM affect the amount of heat energy (Q) transfer between the ambient air and PCM and the energy conversion efficiency (ηE), respectively, where the amount of electric energy is given by Q × ηE. The increase in Q caused by an increase in the latent heat of the PCM was almost independent of the thermal resistance between the TED/PCM interface and air. However, the increase in ηE caused by an increase in the thermal conductivity of the PCM decreased as the thermal resistance between the TED/PCM interface and air increased. These results indicate that the techniques to improve the power generation characteristics by increasing the thermal conductivity of PCM, which have been frequently investigated in recent years, are effective only when the thermal resistance between the TED/PCM interface and ambient air is small.
{"title":"Analysis of reducing thermal resistance between the PCM and ambient air for improving the power generation characteristics of PCM-based thermoelectric power generators","authors":"K. Suemori, Yusuke Komazaki, Nobuko Fukuda","doi":"10.1063/5.0198744","DOIUrl":"https://doi.org/10.1063/5.0198744","url":null,"abstract":"A power generator comprising a thermoelectric device (TED) and a phase change material (PCM) allows energy harvesting from ambient temperature variations, which exist ubiquitously; thus, such a device has received considerable attention as an energy harvester that can operate at any location. We developed a model for estimating the characteristics of a power generator in ambient air, whose temperature is forcibly changed between two temperature values, such as when an air conditioner is turned on and off. We calculated the influence of latent heat and thermal conductivity of the PCM on the characteristics of power generators with various thermal resistances between the TED/PCM interface and ambient air. Latent heat and thermal conductivity of the PCM affect the amount of heat energy (Q) transfer between the ambient air and PCM and the energy conversion efficiency (ηE), respectively, where the amount of electric energy is given by Q × ηE. The increase in Q caused by an increase in the latent heat of the PCM was almost independent of the thermal resistance between the TED/PCM interface and air. However, the increase in ηE caused by an increase in the thermal conductivity of the PCM decreased as the thermal resistance between the TED/PCM interface and air increased. These results indicate that the techniques to improve the power generation characteristics by increasing the thermal conductivity of PCM, which have been frequently investigated in recent years, are effective only when the thermal resistance between the TED/PCM interface and ambient air is small.","PeriodicalId":502933,"journal":{"name":"Journal of Applied Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140966121","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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