The reversible transformation of radiative cooling and solar heating of the film is significant for a building's energy conservation and carbon emission reduction. The current technology is constrained by its reliance on complex control mechanisms and a narrow control scope, which collectively impede its practical deployment. In this Letter, we introduce an all-season smart film, a multilayer film composed of In3SbTe2 (IST), CaF2, and ZnS on an Al substrate, which possesses the unique ability to synergistically modulate solar-thermal radiation. The solar absorptance and infrared emittance are (anormal, εnormal) = (0.829, 0.055) for the solar heating mode and (0.361, 0.835) for the radiative cooling mode, respectively. The underlying mechanism pertains to the Fabry–Pérot resonance and antireflection. The modulation property of the smart film remains excellent even when the incident angle is large. Furthermore, the smart film is capable of achieving multilevel modulation through the alteration of the crystalline IST percentage. The excellent modulation properties of the smart film are substantiated through a quantitative assessment of the net heat flux for terrestrial applications. This analysis reveals that the smart film with amorphous IST achieves a solar heating flux of 800 W/m2 at 250 K, while for crystalline IST it exhibits a radiative cooling flux of 600 W/m2 at 330 K. Such a simple multilayer structure can be easily fabricated, which would facilitate the advancement and practical implementation of an all-season smart film.
{"title":"In3SbTe2-based all-season smart film with synergistic modulation of solar and thermal radiation","authors":"Bowei Xie, Linhua Liu","doi":"10.1063/5.0253948","DOIUrl":"https://doi.org/10.1063/5.0253948","url":null,"abstract":"The reversible transformation of radiative cooling and solar heating of the film is significant for a building's energy conservation and carbon emission reduction. The current technology is constrained by its reliance on complex control mechanisms and a narrow control scope, which collectively impede its practical deployment. In this Letter, we introduce an all-season smart film, a multilayer film composed of In3SbTe2 (IST), CaF2, and ZnS on an Al substrate, which possesses the unique ability to synergistically modulate solar-thermal radiation. The solar absorptance and infrared emittance are (anormal, εnormal) = (0.829, 0.055) for the solar heating mode and (0.361, 0.835) for the radiative cooling mode, respectively. The underlying mechanism pertains to the Fabry–Pérot resonance and antireflection. The modulation property of the smart film remains excellent even when the incident angle is large. Furthermore, the smart film is capable of achieving multilevel modulation through the alteration of the crystalline IST percentage. The excellent modulation properties of the smart film are substantiated through a quantitative assessment of the net heat flux for terrestrial applications. This analysis reveals that the smart film with amorphous IST achieves a solar heating flux of 800 W/m2 at 250 K, while for crystalline IST it exhibits a radiative cooling flux of 600 W/m2 at 330 K. Such a simple multilayer structure can be easily fabricated, which would facilitate the advancement and practical implementation of an all-season smart film.","PeriodicalId":8094,"journal":{"name":"Applied Physics Letters","volume":"91 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-03-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143660579","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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}
Pinglan Yan, Yuke Song, Shifang Li, Xizhi Shi, Jin Li, Chaoyu He, Tao Ouyang, Chao Tang, Jianxin Zhong
Recently, constructing three-dimensional materials through two-dimensional materials is attracting research attention in both experiment and theory due to the properties beyond ordinary 3D materials. In this work, we propose a three-dimensional carbon allotrope by interpenetrating α-graphyne sheets with van der Waals interactions and study its structural and electronic properties by first-principles calculations and tight-binding methods. Our calculations show that the energy of this interpenetrated α-graphyne is slightly lower than that of the α-graphyne nanosheet due to the weak van der Waals interactions, and its dynamical and thermodynamical stabilities are further confirmed by first-principles calculations. Remarkably, 3D interpenetrated α-graphyne is a semimetal with both Dirac nodal loops and triply degenerate nodal points near the Fermi level and the Fermi velocities at these nodal points are very high. These properties are superior to 2D α-graphyne and ordinary 3D carbon materials. Our work not only proposes a type of 3D carbon material with multiple types of fermions for carbon-based high-speed nanoelectronic devices but also shows that interpenetrating 2D materials with large hollows is a promising method for constructing 3D materials.
{"title":"Coexistence of Dirac nodal loops and triply degenerate nodal points in three-dimensional interpenetrated α-graphyne","authors":"Pinglan Yan, Yuke Song, Shifang Li, Xizhi Shi, Jin Li, Chaoyu He, Tao Ouyang, Chao Tang, Jianxin Zhong","doi":"10.1063/5.0251784","DOIUrl":"https://doi.org/10.1063/5.0251784","url":null,"abstract":"Recently, constructing three-dimensional materials through two-dimensional materials is attracting research attention in both experiment and theory due to the properties beyond ordinary 3D materials. In this work, we propose a three-dimensional carbon allotrope by interpenetrating α-graphyne sheets with van der Waals interactions and study its structural and electronic properties by first-principles calculations and tight-binding methods. Our calculations show that the energy of this interpenetrated α-graphyne is slightly lower than that of the α-graphyne nanosheet due to the weak van der Waals interactions, and its dynamical and thermodynamical stabilities are further confirmed by first-principles calculations. Remarkably, 3D interpenetrated α-graphyne is a semimetal with both Dirac nodal loops and triply degenerate nodal points near the Fermi level and the Fermi velocities at these nodal points are very high. These properties are superior to 2D α-graphyne and ordinary 3D carbon materials. Our work not only proposes a type of 3D carbon material with multiple types of fermions for carbon-based high-speed nanoelectronic devices but also shows that interpenetrating 2D materials with large hollows is a promising method for constructing 3D materials.","PeriodicalId":8094,"journal":{"name":"Applied Physics Letters","volume":"70 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-03-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143660980","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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}
S. F. Chichibu, K. Kikuchi, B. Moody, S. Mita, R. Collazo, Z. Sitar, Y. Kumagai, S. Ishibashi, A. Uedono, K. Shima
Roles of Al-vacancy (VAl) complexes on the cathodoluminescence (CL) spectra of Si-doped AlN grown by halide vapor phase epitaxy (HVPE) on a physical-vapor-transported (0001) AlN substrate are described, making a connection with the results of positron annihilation measurements. A combination of HVPE and AlN substrate enabled decreasing deleterious carbon concentration and dislocation density, respectively, thus accentuating the influences of VAl-complexes on the luminescence processes. A low-temperature CL spectrum of unintentionally doped AlN exhibited predominant excitonic emissions at around 6 eV and a marginal deep-state emission band at around 3.7 eV that originates from residual carbon (<1016 cm−3) on nitrogen sites (CN). However, the sample was revealed to contain a considerable amount (∼1017 cm−3) of vacancy clusters, most likely comprising a VAl and nitrogen-vacancies (VN), namely, VAlVN1−2, which act as nonradiative recombination centers that decrease overall CL intensity at elevated temperatures. With increasing Si-doping concentration ([Si]), major vacancy species progressively changed from VAlVN1−2 to VAlON1−2, where ON is oxygen on N sites, which exhibit other deep-state emission bands ranging from 3.2 to 3.5 eV. Further increase in [Si] gave rise to the formation of donor-compensating defects comprising VAl and Si on the second-nearest-neighbor Al sites (SiAl), abbreviated by VAl−SiAln, which exhibit emission shoulders at around 2.9–3.0 eV. When [Si] exceeded 5 × 1018 cm−3, an emission band at around 4.5 eV emerged, which had been ascribed to originate from the nearest-neighbor SiAlCN complexes. Because VAl-complexes, including those containing impurities, are thermally stable, incorporation of vacancies should be blocked at the growth stage.
{"title":"Roles of Al-vacancy complexes on the luminescence spectra of low dislocation density Si-doped AlN grown by halide vapor phase epitaxy","authors":"S. F. Chichibu, K. Kikuchi, B. Moody, S. Mita, R. Collazo, Z. Sitar, Y. Kumagai, S. Ishibashi, A. Uedono, K. Shima","doi":"10.1063/5.0252149","DOIUrl":"https://doi.org/10.1063/5.0252149","url":null,"abstract":"Roles of Al-vacancy (VAl) complexes on the cathodoluminescence (CL) spectra of Si-doped AlN grown by halide vapor phase epitaxy (HVPE) on a physical-vapor-transported (0001) AlN substrate are described, making a connection with the results of positron annihilation measurements. A combination of HVPE and AlN substrate enabled decreasing deleterious carbon concentration and dislocation density, respectively, thus accentuating the influences of VAl-complexes on the luminescence processes. A low-temperature CL spectrum of unintentionally doped AlN exhibited predominant excitonic emissions at around 6 eV and a marginal deep-state emission band at around 3.7 eV that originates from residual carbon (&lt;1016 cm−3) on nitrogen sites (CN). However, the sample was revealed to contain a considerable amount (∼1017 cm−3) of vacancy clusters, most likely comprising a VAl and nitrogen-vacancies (VN), namely, VAlVN1−2, which act as nonradiative recombination centers that decrease overall CL intensity at elevated temperatures. With increasing Si-doping concentration ([Si]), major vacancy species progressively changed from VAlVN1−2 to VAlON1−2, where ON is oxygen on N sites, which exhibit other deep-state emission bands ranging from 3.2 to 3.5 eV. Further increase in [Si] gave rise to the formation of donor-compensating defects comprising VAl and Si on the second-nearest-neighbor Al sites (SiAl), abbreviated by VAl−SiAln, which exhibit emission shoulders at around 2.9–3.0 eV. When [Si] exceeded 5 × 1018 cm−3, an emission band at around 4.5 eV emerged, which had been ascribed to originate from the nearest-neighbor SiAlCN complexes. Because VAl-complexes, including those containing impurities, are thermally stable, incorporation of vacancies should be blocked at the growth stage.","PeriodicalId":8094,"journal":{"name":"Applied Physics Letters","volume":"43 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-03-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143660486","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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}
Mengxiang Yang, Hongyu Zhu, Shuai Duan, Jingyang Du, Shangsheng Li, Xiaobing Liu, Taichao Su
Paracostibite (CoSbS) has received significant attention as a thermoelectric material due to its earth-abundant, low-toxicity, and cost-effective constituent elements, as well as its potential application in power generation. In this work, both the conventional orthorhombic and distinct cubic CoSbS compounds were facilely synthesized using the high-pressure and high-temperature method. It was found that cubic CoSbS exhibits a higher solid solubility of Ni at the Co site compared to the orthorhombic sample. The high-density point defect NiCo in cubic CoSbS results in enhanced phonon scattering, thereby sharply suppressing phonon thermal conductivity. First-principles calculations show that the cubic structure of CoSbS exhibits higher band degeneracy and greater band dispersion compared to the orthorhombic structure, resulting in superior electrical transport properties. As a result, an enhanced figure of merit zT ∼ 0.37 was obtained at 773 K for cubic Ni0.1Co0.9SbS, which is approximately 16% higher than that of the orthorhombic sample prepared by the same method. These results indicate that employing high-pressure and high-temperature synthesis techniques offers a practical and controllable approach to modulate the crystal structure and thermoelectric performance of CoSbS.
{"title":"High-pressure and high-temperature induced phase transition and thermoelectric property modulation in CoSbS","authors":"Mengxiang Yang, Hongyu Zhu, Shuai Duan, Jingyang Du, Shangsheng Li, Xiaobing Liu, Taichao Su","doi":"10.1063/5.0259170","DOIUrl":"https://doi.org/10.1063/5.0259170","url":null,"abstract":"Paracostibite (CoSbS) has received significant attention as a thermoelectric material due to its earth-abundant, low-toxicity, and cost-effective constituent elements, as well as its potential application in power generation. In this work, both the conventional orthorhombic and distinct cubic CoSbS compounds were facilely synthesized using the high-pressure and high-temperature method. It was found that cubic CoSbS exhibits a higher solid solubility of Ni at the Co site compared to the orthorhombic sample. The high-density point defect NiCo in cubic CoSbS results in enhanced phonon scattering, thereby sharply suppressing phonon thermal conductivity. First-principles calculations show that the cubic structure of CoSbS exhibits higher band degeneracy and greater band dispersion compared to the orthorhombic structure, resulting in superior electrical transport properties. As a result, an enhanced figure of merit zT ∼ 0.37 was obtained at 773 K for cubic Ni0.1Co0.9SbS, which is approximately 16% higher than that of the orthorhombic sample prepared by the same method. These results indicate that employing high-pressure and high-temperature synthesis techniques offers a practical and controllable approach to modulate the crystal structure and thermoelectric performance of CoSbS.","PeriodicalId":8094,"journal":{"name":"Applied Physics Letters","volume":"197 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-03-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143640052","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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}
Daniel N. Shanks, Jason P. Allmaras, Sahil R. Patel, Boris A. Korzh, Emma E. Wollman, Frank Greer, Andrew D. Beyer, Matthew D. Shaw
Superconducting nanowire single photon detectors (SNSPDs) have shown remarkable photon detection characteristics, and scalable architectures allow for the fabrication of SNSPD cameras with over a hundred thousand pixels. Producing such large format devices requires the use of a high throughput lithography process such as stepper photolithography. This restricts nanowire widths to the resolution limit of the photolithography system, which limits performance, particularly for mid-infrared wavelengths. In this paper, we develop an SNSPD fabrication process that uses bidirectional atomic layer etching to reduce nanowire widths by > 100 nm, achieving performance that has only previously been attained using low throughput electron beam lithography. This fabrication process will allow for high-pixel count SNSPD cameras with improved performance due to reduced nanowire widths.
{"title":"Line width narrowing of superconducting nanowire single photon detectors using atomic layer etching","authors":"Daniel N. Shanks, Jason P. Allmaras, Sahil R. Patel, Boris A. Korzh, Emma E. Wollman, Frank Greer, Andrew D. Beyer, Matthew D. Shaw","doi":"10.1063/5.0252913","DOIUrl":"https://doi.org/10.1063/5.0252913","url":null,"abstract":"Superconducting nanowire single photon detectors (SNSPDs) have shown remarkable photon detection characteristics, and scalable architectures allow for the fabrication of SNSPD cameras with over a hundred thousand pixels. Producing such large format devices requires the use of a high throughput lithography process such as stepper photolithography. This restricts nanowire widths to the resolution limit of the photolithography system, which limits performance, particularly for mid-infrared wavelengths. In this paper, we develop an SNSPD fabrication process that uses bidirectional atomic layer etching to reduce nanowire widths by &gt; 100 nm, achieving performance that has only previously been attained using low throughput electron beam lithography. This fabrication process will allow for high-pixel count SNSPD cameras with improved performance due to reduced nanowire widths.","PeriodicalId":8094,"journal":{"name":"Applied Physics Letters","volume":"7 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-03-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143640057","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 inverse design of solid-state materials with targeted properties represents a significant challenge in materials science, particularly for piezoelectric semiconductors where both structural symmetry and electronic properties must be carefully controlled. Here, we employ the simplified line-input crystal-encoding system representation combined with the MatterGPT framework for discovering potential piezoelectric semiconductors. By training on a curated dataset of 1556 piezoelectric materials from the Materials Project database, our model learns to generate crystal structures with targeted piezoelectric properties through an autoregressive sampling process. Starting from approximately 5000 generated structures, we implemented a comprehensive screening workflow incorporating structural validity, thermodynamic stability, and property verification. This approach identified several promising candidates from 4100 reconstructed structures, each representing compounds unrecorded in existing databases. Among these, the most notable material demonstrated a piezoelectric stress coefficient of 25.9 C/m2 in the e[1,6] direction. Additionally, these materials demonstrate suitable bandgaps ranging from 1.63 to 3.61 eV, suggesting potential applications in high-sensitivity sensors and high-temperature electronics. Our work demonstrates the effectiveness of combining crystal structure language encoding with generative models for accelerating the discovery of functional materials with targeted properties.
{"title":"Inverse design of high-performance piezoelectric semiconductors via advanced crystal representation and large language models","authors":"Chen Zhang, Siyuan Lv, Haojie Gong, Qianxi Cheng, Junwei Guo, Zheng Duanmu, Hang Xiao","doi":"10.1063/5.0247738","DOIUrl":"https://doi.org/10.1063/5.0247738","url":null,"abstract":"The inverse design of solid-state materials with targeted properties represents a significant challenge in materials science, particularly for piezoelectric semiconductors where both structural symmetry and electronic properties must be carefully controlled. Here, we employ the simplified line-input crystal-encoding system representation combined with the MatterGPT framework for discovering potential piezoelectric semiconductors. By training on a curated dataset of 1556 piezoelectric materials from the Materials Project database, our model learns to generate crystal structures with targeted piezoelectric properties through an autoregressive sampling process. Starting from approximately 5000 generated structures, we implemented a comprehensive screening workflow incorporating structural validity, thermodynamic stability, and property verification. This approach identified several promising candidates from 4100 reconstructed structures, each representing compounds unrecorded in existing databases. Among these, the most notable material demonstrated a piezoelectric stress coefficient of 25.9 C/m2 in the e[1,6] direction. Additionally, these materials demonstrate suitable bandgaps ranging from 1.63 to 3.61 eV, suggesting potential applications in high-sensitivity sensors and high-temperature electronics. Our work demonstrates the effectiveness of combining crystal structure language encoding with generative models for accelerating the discovery of functional materials with targeted properties.","PeriodicalId":8094,"journal":{"name":"Applied Physics Letters","volume":"96 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-03-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143640375","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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}
Hu Sun, Junhao Ding, Run Zhao, Ju Gao, Guozhen Liu, Jie Qiu
Theoretical modulation of the current rectification ratio and turn-on voltage of p–n diodes by selecting semiconductor materials with appropriate Fermi levels remains challenging in practice. Key obstacles include lattice matching, thermal compatibility, and chemical stability during material synthesis. Most nonvolatile diodes are realized in ferroelectric systems, but size effects in ferroelectrics limit device miniaturization. In this work, we demonstrate an electrically tunable nonvolatile diode based on non-ferroelectric two-dimensional (2D) van der Waals heterostructures of GeSe and a quasi-2D electron gas on SrTiO3 surfaces. The device achieves a tunable current rectification ratio of 103–104 without gate bias application, with a continuously adjustable turn-on voltage from 0.1 to 2.1 V. Furthermore, the heterostructure demonstrates nonvolatile resistance switching behavior induced by applied bias voltage. The integration of electrical tunability and non-volatility in a single non-ferroelectric diode offers a promising platform for low-dimensional nonvolatile memory devices with multi-bit storage capability.
{"title":"Electrically tunable nonvolatile 2D van der Waals p–n heterostructures based on GeSe-quasi 2D electron gas on the SrTiO3 surface","authors":"Hu Sun, Junhao Ding, Run Zhao, Ju Gao, Guozhen Liu, Jie Qiu","doi":"10.1063/5.0258461","DOIUrl":"https://doi.org/10.1063/5.0258461","url":null,"abstract":"Theoretical modulation of the current rectification ratio and turn-on voltage of p–n diodes by selecting semiconductor materials with appropriate Fermi levels remains challenging in practice. Key obstacles include lattice matching, thermal compatibility, and chemical stability during material synthesis. Most nonvolatile diodes are realized in ferroelectric systems, but size effects in ferroelectrics limit device miniaturization. In this work, we demonstrate an electrically tunable nonvolatile diode based on non-ferroelectric two-dimensional (2D) van der Waals heterostructures of GeSe and a quasi-2D electron gas on SrTiO3 surfaces. The device achieves a tunable current rectification ratio of 103–104 without gate bias application, with a continuously adjustable turn-on voltage from 0.1 to 2.1 V. Furthermore, the heterostructure demonstrates nonvolatile resistance switching behavior induced by applied bias voltage. The integration of electrical tunability and non-volatility in a single non-ferroelectric diode offers a promising platform for low-dimensional nonvolatile memory devices with multi-bit storage capability.","PeriodicalId":8094,"journal":{"name":"Applied Physics Letters","volume":"61 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-03-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143640475","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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}
Nb2GeTe4, a two-dimensional ferroelastic semiconductor, has garnered intense research interest due to its nontrivial physicochemical characteristics of high carrier mobility as well as extraordinary ferroelasticity and optical absorbance along with potential applications in electronic and optoelectronic devices. In this work, the high-pressure structural, vibrational, and electrical transport properties of Nb2GeTe4 up to 60.0 GPa under different hydrostatic environments were systematically studied by Raman spectroscopy, electrical conductivity, and first-principles theoretical calculations. Under non-hydrostatic compression, Nb2GeTe4 experienced a metallization at 11.8 GPa originating from the closure of bandgap due to the considerable compression of interlayer distance and sequential an isostructural phase transition (IPT) at 26.5 GPa. The comparable metallization pressure and the pronounced delay of IPT by ∼4.0 GPa under hydrostatic condition can be reasonably interpreted by the influence of deviatoric stress. Upon decompression, the phase transition of Nb2GeTe4 was demonstrated to be reversible with the possible structural destruction under different hydrostatic environments. Moreover, Nb2GeTe4 underwent a Ohmic-to-super-Ohmic conversion at 1000 mV under high pressure, which was presumably caused by the higher sinusoidal voltage than its thermal voltage. These findings enrich our foundational comprehension on high-pressure physicochemical properties of Nb2GeTe4, thereby fostering its potential applications in electronic and optoelectronic devices.
{"title":"Observation of electronic and structural transitions in two-dimensional ferroelastic semiconductor of Nb2GeTe4 via pressure manipulation","authors":"Meiling Hong, Lidong Dai, Haiying Hu, Chuang Li, Mingyu Wu, Yu He","doi":"10.1063/5.0257969","DOIUrl":"https://doi.org/10.1063/5.0257969","url":null,"abstract":"Nb2GeTe4, a two-dimensional ferroelastic semiconductor, has garnered intense research interest due to its nontrivial physicochemical characteristics of high carrier mobility as well as extraordinary ferroelasticity and optical absorbance along with potential applications in electronic and optoelectronic devices. In this work, the high-pressure structural, vibrational, and electrical transport properties of Nb2GeTe4 up to 60.0 GPa under different hydrostatic environments were systematically studied by Raman spectroscopy, electrical conductivity, and first-principles theoretical calculations. Under non-hydrostatic compression, Nb2GeTe4 experienced a metallization at 11.8 GPa originating from the closure of bandgap due to the considerable compression of interlayer distance and sequential an isostructural phase transition (IPT) at 26.5 GPa. The comparable metallization pressure and the pronounced delay of IPT by ∼4.0 GPa under hydrostatic condition can be reasonably interpreted by the influence of deviatoric stress. Upon decompression, the phase transition of Nb2GeTe4 was demonstrated to be reversible with the possible structural destruction under different hydrostatic environments. Moreover, Nb2GeTe4 underwent a Ohmic-to-super-Ohmic conversion at 1000 mV under high pressure, which was presumably caused by the higher sinusoidal voltage than its thermal voltage. These findings enrich our foundational comprehension on high-pressure physicochemical properties of Nb2GeTe4, thereby fostering its potential applications in electronic and optoelectronic devices.","PeriodicalId":8094,"journal":{"name":"Applied Physics Letters","volume":"69 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-03-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143640461","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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}
Esa Alakoski, Sami Kinnunen, Girish C. Tewari, Jaakko Julin, Antti J. Soininen, Maarit Karppinen
Thin films are an effective way of manufacturing thermoelectric (TE) sensors for biomedical devices and wearable electronics. Excellent conformality and sub-nanometer thickness control of atomic layer deposition (ALD) make it a promising method of preparing TE thin films on flexible polymer and textile substrates suitable for sensor use. Here, Al-doped ZnO films were deposited on flexible perforated polyethylene terephthalate (PET) templates with 50/1 diethylzinc/trimethylaluminum pulsing ratio at a low temperature of 100 °C. Thermoelectric properties of the resulting nanocomposites were measured. The application potential of the present ALD-made TE coatings on flexible PET films for future roll-to-roll fabrication is discussed.
{"title":"Toward roll-to-roll ALD of thermoelectric Al-doped ZnO thin films on flexible nanostructured PET membranes","authors":"Esa Alakoski, Sami Kinnunen, Girish C. Tewari, Jaakko Julin, Antti J. Soininen, Maarit Karppinen","doi":"10.1063/5.0245804","DOIUrl":"https://doi.org/10.1063/5.0245804","url":null,"abstract":"Thin films are an effective way of manufacturing thermoelectric (TE) sensors for biomedical devices and wearable electronics. Excellent conformality and sub-nanometer thickness control of atomic layer deposition (ALD) make it a promising method of preparing TE thin films on flexible polymer and textile substrates suitable for sensor use. Here, Al-doped ZnO films were deposited on flexible perforated polyethylene terephthalate (PET) templates with 50/1 diethylzinc/trimethylaluminum pulsing ratio at a low temperature of 100 °C. Thermoelectric properties of the resulting nanocomposites were measured. The application potential of the present ALD-made TE coatings on flexible PET films for future roll-to-roll fabrication is discussed.","PeriodicalId":8094,"journal":{"name":"Applied Physics Letters","volume":"55 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-03-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143640478","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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}
Prachi Pohekar, Bhanu B. Upadhyay, Bazila Parvez, Swaroop Ganguly, Dipankar Saha
The GaN family as an electronic material and AlGaN/GaN high electron mobility transistors (HEMTs) as electronic devices have found their widespread usage in power electronics and radio frequency (RF) applications. The threshold voltage is a crucial parameter, and application-specific threshold voltage is a requirement for this technology. A large positive threshold voltage with enhancement-mode operation is useful for power electronics. A depletion-mode transistor is used for radio frequency (RF) applications where the electron mobility is much larger in the channel region due to low interface roughness. A multi-threshold voltage transistor is a desired feature to reduce nonlinearity through compensation in RF applications. We address the issue with threshold voltage by demonstrating a programmable threshold AlGaN/GaN transistor using a dielectric stack as the charge-trapping layer. We have fabricated and characterized a triple-layer dielectric gate stack for AlGaN/GaN metal–insulator–semiconductor HEMTs. The gate stack comprises a high-k tantalum oxide sandwiched between two aluminum oxide layers. The structure is analogous to the polysilicon–aluminum oxide–nitride–oxide–silicon memory used in silicon technology. In addition to providing a large programmable threshold voltage window, the fabricated diodes reduce the gate leakage current by more than four orders of magnitude. The experimental observations are explained by the band edge alignment of the AlGaN/GaN heterostructure with the dielectric stack and using a charge-trapping process by a high positive program voltage.
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