Bio-inspired visuomorphic vision integrates multi-dimensional information (spectrum, spatial, temporal, and so on), providing an effective computational paradigm for sensing a visual scene in the physical world. Using photosensors with multi-dimensional information processing functionality to split complex optical information into visible and ultraviolet channels for separate perception and processing is the basis for constructing tetrachromatic vision systems. Here, by modulating the transport dynamics of photogenerated excitons between pentacene and ZnO thin films, both wavelength-dependent volatile positive photoconductance and non-volatile negative photoconductance characteristics are coupled into a single optoelectronic transistor. Utilizing the optoelectronic transistor as the tetrachromatic sensor, the constructed in-sensor computing system can effectively extract and identify the types of visible objects (99%) and the motion direction of ultraviolet objects (97%). This work provides a foundational hardware platform for intelligent artificial vision systems.
{"title":"Tetrachromatic optoelectronic transistor with multi-dimensional information processing functionality for in-sensor motion perception","authors":"Wanxin Huang, Yiru Wang, Shanshuo Liu, Jianyu Ming, Yannan Xie, Li Gao, Linghai Xie, Haifeng Ling","doi":"10.1063/5.0303796","DOIUrl":"https://doi.org/10.1063/5.0303796","url":null,"abstract":"Bio-inspired visuomorphic vision integrates multi-dimensional information (spectrum, spatial, temporal, and so on), providing an effective computational paradigm for sensing a visual scene in the physical world. Using photosensors with multi-dimensional information processing functionality to split complex optical information into visible and ultraviolet channels for separate perception and processing is the basis for constructing tetrachromatic vision systems. Here, by modulating the transport dynamics of photogenerated excitons between pentacene and ZnO thin films, both wavelength-dependent volatile positive photoconductance and non-volatile negative photoconductance characteristics are coupled into a single optoelectronic transistor. Utilizing the optoelectronic transistor as the tetrachromatic sensor, the constructed in-sensor computing system can effectively extract and identify the types of visible objects (99%) and the motion direction of ultraviolet objects (97%). This work provides a foundational hardware platform for intelligent artificial vision systems.","PeriodicalId":8094,"journal":{"name":"Applied Physics Letters","volume":"46 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145759394","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}
Achieving fully electrical and easily integrated programmable spin logic within a single device using spin–orbit torque (SOT)-driven perpendicular magnetization switching (PMS) remains a key challenge for realizing scalable and energy-efficient spin logic-in-memory computing. Here, we demonstrate controllable field-free SOT-driven PMS by the geometric asymmetry of current distribution in a “T-shaped” Pt/CoPt architecture. Deterministic clockwise/counterclockwise PMS is observed when applying current pulses along the left/right arms of the T-architecture, which has been attributed to the combined effect of geometrically curved current channel-induced Oersted field and inhomogeneous spatial distribution of spin currents. Furthermore, by implementing a three-step sequential pulsing scheme that precisely controls channel selection, an initial control current pulse, and two subsequent control pulses, we demonstrate the complete set of 16 Boolean logic functions within a single device. This simple material-agnostic and integration-friendly approach provides a pathway for developing fully electrical controllable SOT-based spin logic and in-memory computing devices.
{"title":"Geometric symmetry breaking of current distribution enables field-free programmable spin logic in T-shaped architecture","authors":"Zhenxing Wang, Qian Wang, Dong Wang, Xiang Han, Chuanwei Feng, Xinglong Ye, Lihui Bai, Shishen Yan, Yufeng Tian","doi":"10.1063/5.0295548","DOIUrl":"https://doi.org/10.1063/5.0295548","url":null,"abstract":"Achieving fully electrical and easily integrated programmable spin logic within a single device using spin–orbit torque (SOT)-driven perpendicular magnetization switching (PMS) remains a key challenge for realizing scalable and energy-efficient spin logic-in-memory computing. Here, we demonstrate controllable field-free SOT-driven PMS by the geometric asymmetry of current distribution in a “T-shaped” Pt/CoPt architecture. Deterministic clockwise/counterclockwise PMS is observed when applying current pulses along the left/right arms of the T-architecture, which has been attributed to the combined effect of geometrically curved current channel-induced Oersted field and inhomogeneous spatial distribution of spin currents. Furthermore, by implementing a three-step sequential pulsing scheme that precisely controls channel selection, an initial control current pulse, and two subsequent control pulses, we demonstrate the complete set of 16 Boolean logic functions within a single device. This simple material-agnostic and integration-friendly approach provides a pathway for developing fully electrical controllable SOT-based spin logic and in-memory computing devices.","PeriodicalId":8094,"journal":{"name":"Applied Physics Letters","volume":"3 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145759837","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}
Michael T. Hatzon, Eugene N. Ivanov, Aaron Quiskamp, Michael E. Tobar
We report high-resolution measurements of thermal fluctuations in microwave and mechanical resonators using a dual-channel readout system. The latter comprises a low-noise amplifier, an I/Q-mixer, and a cross-correlator. We discovered that, under certain conditions, the intrinsic fluctuations of the low-noise amplifier, which are common to both channels of the readout system, are averaged out when computing the voltage noise cross-spectrum between the mixer's outputs. The suppression of the amplifier's technical fluctuations significantly improves the contrast of the thermal noise peaks exhibited by the resonators. Thus, for the room-temperature-stabilized 9 GHz sapphire-loaded cavity resonator, we observed more than 16 dB improvement in the thermal noise peak contrast relative to the single-channel measurements. The ability of the dual-channel readout system to discriminate between the broad- and narrow-band fluctuations may benefit the search for dark matter, which relies on the use of cryogenic microwave resonators.
{"title":"The study of thermal fluctuations in microwave and mechanical resonators","authors":"Michael T. Hatzon, Eugene N. Ivanov, Aaron Quiskamp, Michael E. Tobar","doi":"10.1063/5.0305008","DOIUrl":"https://doi.org/10.1063/5.0305008","url":null,"abstract":"We report high-resolution measurements of thermal fluctuations in microwave and mechanical resonators using a dual-channel readout system. The latter comprises a low-noise amplifier, an I/Q-mixer, and a cross-correlator. We discovered that, under certain conditions, the intrinsic fluctuations of the low-noise amplifier, which are common to both channels of the readout system, are averaged out when computing the voltage noise cross-spectrum between the mixer's outputs. The suppression of the amplifier's technical fluctuations significantly improves the contrast of the thermal noise peaks exhibited by the resonators. Thus, for the room-temperature-stabilized 9 GHz sapphire-loaded cavity resonator, we observed more than 16 dB improvement in the thermal noise peak contrast relative to the single-channel measurements. The ability of the dual-channel readout system to discriminate between the broad- and narrow-band fluctuations may benefit the search for dark matter, which relies on the use of cryogenic microwave resonators.","PeriodicalId":8094,"journal":{"name":"Applied Physics Letters","volume":"107 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145759840","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}
Yiwen Song, Eungkyun Kim, Jimy Encomendero, Seokjun Kim, Daniel C. Shoemaker, Yu-Hsin Chen, Debdeep Jena, Huili Grace Xing, Sukwon Choi
AlN/GaN/AlN high electron mobility transistors (HEMTs) have demonstrated exceptional potential for surpassing the electrical limitations of conventional AlGaN/GaN HEMTs. This study investigates the thermal performance of two types of AlN/GaN/AlN HEMTs with homoepitaxial AlN buffer layers grown on AlN substrates: an AlN/GaN/AlN single-crystal HEMT (AlN XHEMT) featuring a pseudomorphic/thin GaN channel and a conventional structure with a relaxed/thick GaN channel. Frequency- and time-domain thermoreflectance measurements reveal bulk-like thermal conductivity in the homoepitaxial AlN buffer layer, with negligible thermal boundary resistance at the AlN buffer/substrate interface. Consequently, Raman thermometry demonstrates that the AlN XHEMT with a thin (∼20 nm) pseudomorphically strained GaN channel exhibits better thermal performance than identical HEMT layer structures grown on a 4H-SiC substrate, despite 4H-SiC possessing a higher thermal conductivity. In addition, the AlN XHEMT exhibits a 22% lower channel temperature under 14 W/mm power density than the AlN/GaN/AlN-on-AlN HEMT that employs a thick (275 nm) relaxed GaN channel. These findings highlight that AlN XHEMTs offer not only electrical but also thermal advantages for high-power and high-frequency applications.
{"title":"Enhanced thermal performance of AlN/GaN/AlN XHEMTs on bulk AlN by suppression of phonon-boundary scattering","authors":"Yiwen Song, Eungkyun Kim, Jimy Encomendero, Seokjun Kim, Daniel C. Shoemaker, Yu-Hsin Chen, Debdeep Jena, Huili Grace Xing, Sukwon Choi","doi":"10.1063/5.0305053","DOIUrl":"https://doi.org/10.1063/5.0305053","url":null,"abstract":"AlN/GaN/AlN high electron mobility transistors (HEMTs) have demonstrated exceptional potential for surpassing the electrical limitations of conventional AlGaN/GaN HEMTs. This study investigates the thermal performance of two types of AlN/GaN/AlN HEMTs with homoepitaxial AlN buffer layers grown on AlN substrates: an AlN/GaN/AlN single-crystal HEMT (AlN XHEMT) featuring a pseudomorphic/thin GaN channel and a conventional structure with a relaxed/thick GaN channel. Frequency- and time-domain thermoreflectance measurements reveal bulk-like thermal conductivity in the homoepitaxial AlN buffer layer, with negligible thermal boundary resistance at the AlN buffer/substrate interface. Consequently, Raman thermometry demonstrates that the AlN XHEMT with a thin (∼20 nm) pseudomorphically strained GaN channel exhibits better thermal performance than identical HEMT layer structures grown on a 4H-SiC substrate, despite 4H-SiC possessing a higher thermal conductivity. In addition, the AlN XHEMT exhibits a 22% lower channel temperature under 14 W/mm power density than the AlN/GaN/AlN-on-AlN HEMT that employs a thick (275 nm) relaxed GaN channel. These findings highlight that AlN XHEMTs offer not only electrical but also thermal advantages for high-power and high-frequency applications.","PeriodicalId":8094,"journal":{"name":"Applied Physics Letters","volume":"7 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145729104","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 ScAlN film has a large electromechanical coupling and low mechanical loss, enabling RF filters with wide bandwidth, low insertion loss, and a steep filter skirt. In order to meet the growing demand for RF filters operating above 5 GHz, the use of polarization inverted multilayers is continuously being proposed. This Perspective discusses the advantages of overtone mode operation in polarization inverted multilayers for high-frequency bulk acoustic wave (BAW) filter applications: high parallel resonance Qp, high series resonance Qs, high electromechanical coupling, high power capability, and better acoustic isolation from the electrode and supporting medium. Three potential approaches for ScAlN polarization inverted multilayers: film transfer technique, unusual N-polar growth, and external DC voltage application are overviewed. This Perspective includes an experimental demonstration of an acoustic isolation of polarization inverted 30-layer resonators as well as frequency switching between the fundamental mode and the third overtone mode in the currently commercial frequency range of 1.3–3.5 GHz. This article provides a metrics of Q and electromechanical coupling coefficient of recently reported BAW and Lamb wave resonators above 5 GHz, along with experimental data on the elastic tensor, dielectric constant, electromechanical coupling coefficient, temperature coefficient of frequency, and relative Q values in ScxAl1−xN films with varying Sc concentration.
{"title":"A perspective and review of polarization inverted multilayer BAW resonators based on ScAlN piezoelectric films","authors":"Takahiko Yanagitani","doi":"10.1063/5.0281181","DOIUrl":"https://doi.org/10.1063/5.0281181","url":null,"abstract":"The ScAlN film has a large electromechanical coupling and low mechanical loss, enabling RF filters with wide bandwidth, low insertion loss, and a steep filter skirt. In order to meet the growing demand for RF filters operating above 5 GHz, the use of polarization inverted multilayers is continuously being proposed. This Perspective discusses the advantages of overtone mode operation in polarization inverted multilayers for high-frequency bulk acoustic wave (BAW) filter applications: high parallel resonance Qp, high series resonance Qs, high electromechanical coupling, high power capability, and better acoustic isolation from the electrode and supporting medium. Three potential approaches for ScAlN polarization inverted multilayers: film transfer technique, unusual N-polar growth, and external DC voltage application are overviewed. This Perspective includes an experimental demonstration of an acoustic isolation of polarization inverted 30-layer resonators as well as frequency switching between the fundamental mode and the third overtone mode in the currently commercial frequency range of 1.3–3.5 GHz. This article provides a metrics of Q and electromechanical coupling coefficient of recently reported BAW and Lamb wave resonators above 5 GHz, along with experimental data on the elastic tensor, dielectric constant, electromechanical coupling coefficient, temperature coefficient of frequency, and relative Q values in ScxAl1−xN films with varying Sc concentration.","PeriodicalId":8094,"journal":{"name":"Applied Physics Letters","volume":"81 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145729102","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}
Hiroto Yokoyama, Takahiro Umemoto, Akiko Kumada, Masahiro Sato
Accurately predicting the properties of polymers is essential for data-driven materials design. However, such predictions are often challenged by the limited availability of polymer-related data and the fact that high-performance polymers of interest typically lie outside the distribution of existing datasets. In this study, we develop a machine learning model that enhances extrapolative prediction accuracy beyond the training data by leveraging hierarchical, physics-informed descriptors. Specifically, we utilize quantum mechanical (QM) descriptors derived from density functional theory calculations, molecular dynamics (MD) descriptors representing structural and dynamical properties, and force field (FF) descriptors characterizing the interaction parameters used in MD simulations. We investigated two types of extrapolation tasks: extrapolation beyond the range of physical properties and extrapolation to structurally dissimilar molecules. By systematically evaluating all non-zero combinations of QM, MD, and FF descriptors, we find that selected subsets often outperform models using the full descriptor set. This highlights the critical role of dimensionality reduction and descriptor relevance, especially under data-scarce conditions. Comparisons with structure-based models employing molecular fingerprints or molecular graphs further demonstrated the superiority of the proposed model based on selected physics-based descriptors.
{"title":"Extrapolative prediction of polymer properties using physics-informed hierarchical descriptors","authors":"Hiroto Yokoyama, Takahiro Umemoto, Akiko Kumada, Masahiro Sato","doi":"10.1063/5.0292279","DOIUrl":"https://doi.org/10.1063/5.0292279","url":null,"abstract":"Accurately predicting the properties of polymers is essential for data-driven materials design. However, such predictions are often challenged by the limited availability of polymer-related data and the fact that high-performance polymers of interest typically lie outside the distribution of existing datasets. In this study, we develop a machine learning model that enhances extrapolative prediction accuracy beyond the training data by leveraging hierarchical, physics-informed descriptors. Specifically, we utilize quantum mechanical (QM) descriptors derived from density functional theory calculations, molecular dynamics (MD) descriptors representing structural and dynamical properties, and force field (FF) descriptors characterizing the interaction parameters used in MD simulations. We investigated two types of extrapolation tasks: extrapolation beyond the range of physical properties and extrapolation to structurally dissimilar molecules. By systematically evaluating all non-zero combinations of QM, MD, and FF descriptors, we find that selected subsets often outperform models using the full descriptor set. This highlights the critical role of dimensionality reduction and descriptor relevance, especially under data-scarce conditions. Comparisons with structure-based models employing molecular fingerprints or molecular graphs further demonstrated the superiority of the proposed model based on selected physics-based descriptors.","PeriodicalId":8094,"journal":{"name":"Applied Physics Letters","volume":"19 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145729100","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}
M. A. Castellanos-Beltran, A. J. Sirois, D. I. Olaya, J. Biesecker, S. P. Benz, P. F. Hopkins
We present experimental measurements and analysis of leakage errors occurring during resonant digital control of a superconducting qubit. By increasing the amplitude of the digital pulse trains and therefore decreasing the duration of the control gates, from 100 to 40 ns for a π-gate, the leakage error rate measured per Clifford gate in a randomized benchmarking test increases from 4.3×10−4 to 2.4×10−3 and becomes the dominant source of single-qubit gate errors for our qubit; these error rates are 1–2 orders of magnitude larger than we measure when controlling the same qubit using traditional, shaped-analog signals. Simulations show the dominant leakage mechanism arises from the increased spectral power of the pulse trains at the frequency ω12 corresponding to excitations from the first excited state |1⟩ to the second excited state |2⟩. Our measurements demonstrate the fundamental limits to resonant digital control of low-anharmonicity qubits and outline the trade-off between reducing gate times while preserving gate fidelity. We discuss possible strategies for mitigating this issue in future digital control implementations.
{"title":"Characterization of leakage errors in a transmon qubit due to resonant digital control","authors":"M. A. Castellanos-Beltran, A. J. Sirois, D. I. Olaya, J. Biesecker, S. P. Benz, P. F. Hopkins","doi":"10.1063/5.0304764","DOIUrl":"https://doi.org/10.1063/5.0304764","url":null,"abstract":"We present experimental measurements and analysis of leakage errors occurring during resonant digital control of a superconducting qubit. By increasing the amplitude of the digital pulse trains and therefore decreasing the duration of the control gates, from 100 to 40 ns for a π-gate, the leakage error rate measured per Clifford gate in a randomized benchmarking test increases from 4.3×10−4 to 2.4×10−3 and becomes the dominant source of single-qubit gate errors for our qubit; these error rates are 1–2 orders of magnitude larger than we measure when controlling the same qubit using traditional, shaped-analog signals. Simulations show the dominant leakage mechanism arises from the increased spectral power of the pulse trains at the frequency ω12 corresponding to excitations from the first excited state |1⟩ to the second excited state |2⟩. Our measurements demonstrate the fundamental limits to resonant digital control of low-anharmonicity qubits and outline the trade-off between reducing gate times while preserving gate fidelity. We discuss possible strategies for mitigating this issue in future digital control implementations.","PeriodicalId":8094,"journal":{"name":"Applied Physics Letters","volume":"93 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145729105","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 boiling behavior of impacting droplets plays a critical role in spray cooling, directly governing the overall cooling efficiency. Among the various boiling regimes, transitional boiling is particularly significant, as it marks the onset of droplet instability. However, the dynamic interplay between transitional boiling and Leidenfrost rebound remains largely underexplored. In this Letter, we report a universal spontaneous Leidenfrost transitioning (SLT) phenomenon that reveals the coupled evolution of bubble-vapor dynamics, extending the current understanding. Using a custom-designed experimental setup featuring a transparent nano-film heater, we observe that droplets in the SLT regime initially experience vigorous contact boiling following the emergence of a distinctive fingering-crown structure. This stage is followed by repeated contact-levitation cycles, ultimately concluding in Leidenfrost rebound. To explain the formation of the fingering-crown structure, we propose a theoretical model in which a spatial vapor pressure gradient (Δpv) beneath the droplet, which is induced by a hyperbolic vertical vapor velocity distribution, acts as the key mechanism. This model is validated experimentally through combined hydrodynamic (ridge height and dynamic droplet radii) and thermodynamic (heat transfer evolution) analysis. Specifically, our results reveal a characteristic rise-fall pattern between the maximum Δpv and the initial surface temperature, spanning from nucleate boiling to stable Leidenfrost rebound. This trend shows a strong consistency with the predictions of the proposed theoretical model.
{"title":"A spontaneous Leidenfrost transitioning phenomenon","authors":"H. Yang, T. M. Thomas, P. Valluri, K. Sefiane","doi":"10.1063/5.0293908","DOIUrl":"https://doi.org/10.1063/5.0293908","url":null,"abstract":"The boiling behavior of impacting droplets plays a critical role in spray cooling, directly governing the overall cooling efficiency. Among the various boiling regimes, transitional boiling is particularly significant, as it marks the onset of droplet instability. However, the dynamic interplay between transitional boiling and Leidenfrost rebound remains largely underexplored. In this Letter, we report a universal spontaneous Leidenfrost transitioning (SLT) phenomenon that reveals the coupled evolution of bubble-vapor dynamics, extending the current understanding. Using a custom-designed experimental setup featuring a transparent nano-film heater, we observe that droplets in the SLT regime initially experience vigorous contact boiling following the emergence of a distinctive fingering-crown structure. This stage is followed by repeated contact-levitation cycles, ultimately concluding in Leidenfrost rebound. To explain the formation of the fingering-crown structure, we propose a theoretical model in which a spatial vapor pressure gradient (Δpv) beneath the droplet, which is induced by a hyperbolic vertical vapor velocity distribution, acts as the key mechanism. This model is validated experimentally through combined hydrodynamic (ridge height and dynamic droplet radii) and thermodynamic (heat transfer evolution) analysis. Specifically, our results reveal a characteristic rise-fall pattern between the maximum Δpv and the initial surface temperature, spanning from nucleate boiling to stable Leidenfrost rebound. This trend shows a strong consistency with the predictions of the proposed theoretical model.","PeriodicalId":8094,"journal":{"name":"Applied Physics Letters","volume":"53 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145729113","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}
Bingcheng Da, Dinusha Herath Mudiyanselage, Dawei Wang, Junzhe Xie, Xianzhi Wei, Houqiang Fu
This work reports the demonstration of ultrawide bandgap (UWBG) semiconductor AlN trench metal-semiconductor field-effect transistors, where the impact of oxygen thermal annealing treatment on device electrical properties was comprehensively studied. The gate trench regions were characterized by x-ray photoelectron spectroscopy (XPS) and atomic force microscope (AFM). XPS results indicated increased Al–O bonding and stronger formation of AlON layer at the surface, while AFM results showed smoother surface morphology after the treatment. Electrical measurements suggested an increase in the Schottky barrier height under the gate and suppressed fast interface trap states after the treatment. Compared with the device without the treatment, the device with the treatment exhibited more than 22 times improvement in on/off ratio and nearly three times enhancement in breakdown voltage due to reduced leakage and improved interface. Temperature-dependent electrical and interface trap characteristics were also measured and compared. This work can serve as an important reference for the development of UWBG AlN transistors for future high-voltage high-temperature electronics.
{"title":"Effects of oxygen thermal annealing on AlN trench metal-semiconductor field-effect transistors (MESFETs) on single-crystal AlN substrates","authors":"Bingcheng Da, Dinusha Herath Mudiyanselage, Dawei Wang, Junzhe Xie, Xianzhi Wei, Houqiang Fu","doi":"10.1063/5.0304969","DOIUrl":"https://doi.org/10.1063/5.0304969","url":null,"abstract":"This work reports the demonstration of ultrawide bandgap (UWBG) semiconductor AlN trench metal-semiconductor field-effect transistors, where the impact of oxygen thermal annealing treatment on device electrical properties was comprehensively studied. The gate trench regions were characterized by x-ray photoelectron spectroscopy (XPS) and atomic force microscope (AFM). XPS results indicated increased Al–O bonding and stronger formation of AlON layer at the surface, while AFM results showed smoother surface morphology after the treatment. Electrical measurements suggested an increase in the Schottky barrier height under the gate and suppressed fast interface trap states after the treatment. Compared with the device without the treatment, the device with the treatment exhibited more than 22 times improvement in on/off ratio and nearly three times enhancement in breakdown voltage due to reduced leakage and improved interface. Temperature-dependent electrical and interface trap characteristics were also measured and compared. This work can serve as an important reference for the development of UWBG AlN transistors for future high-voltage high-temperature electronics.","PeriodicalId":8094,"journal":{"name":"Applied Physics Letters","volume":"8 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145729109","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}
Alexey A. Sokolik, Azat F. Aminov, Evgenii E. Vdovin, Yurii N. Khanin, Mikhail A. Kashchenko, Denis A. Bandurin, Davit A. Ghazaryan, Sergey V. Morozov, Kostya S. Novoselov
Tunneling conductance between two bilayer graphene (BLG) sheets separated by 2 nm-thick insulating barrier was measured in two devices with the twist angles between BLGs less than 1°. At small bias voltages, tunneling occurs with conservation of energy and momentum at the points of intersection between two relatively shifted Fermi circles. Here, we experimentally found and theoretically described signatures of electron–hole asymmetric band structure of BLG: since holes are heavier, the tunneling conductance is enhanced at the hole doping due to the higher density of states. Another key feature of BLG that we explore is gap opening in a vertical electric field with a strong polarization of electron wave function at van Hove singularities near the gap edges. This polarization, by shifting electron wave function in one BLG closer to or father from the other BLG, gives rise to asymmetric tunneling resonances in the conductance around charge neutrality points, which result in strong sensitivity of the tunneling current to minor changes of the gate voltages. The observed phenomena are reproduced by our theoretical model taking into account electrostatics of the dual-gated structure, quantum capacitance effects, and self-consistent gap openings in both BLGs.
{"title":"Probing the features of electron dispersion by tunneling between slightly twisted bilayer graphene sheets","authors":"Alexey A. Sokolik, Azat F. Aminov, Evgenii E. Vdovin, Yurii N. Khanin, Mikhail A. Kashchenko, Denis A. Bandurin, Davit A. Ghazaryan, Sergey V. Morozov, Kostya S. Novoselov","doi":"10.1063/5.0303858","DOIUrl":"https://doi.org/10.1063/5.0303858","url":null,"abstract":"Tunneling conductance between two bilayer graphene (BLG) sheets separated by 2 nm-thick insulating barrier was measured in two devices with the twist angles between BLGs less than 1°. At small bias voltages, tunneling occurs with conservation of energy and momentum at the points of intersection between two relatively shifted Fermi circles. Here, we experimentally found and theoretically described signatures of electron–hole asymmetric band structure of BLG: since holes are heavier, the tunneling conductance is enhanced at the hole doping due to the higher density of states. Another key feature of BLG that we explore is gap opening in a vertical electric field with a strong polarization of electron wave function at van Hove singularities near the gap edges. This polarization, by shifting electron wave function in one BLG closer to or father from the other BLG, gives rise to asymmetric tunneling resonances in the conductance around charge neutrality points, which result in strong sensitivity of the tunneling current to minor changes of the gate voltages. The observed phenomena are reproduced by our theoretical model taking into account electrostatics of the dual-gated structure, quantum capacitance effects, and self-consistent gap openings in both BLGs.","PeriodicalId":8094,"journal":{"name":"Applied Physics Letters","volume":"29 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145729111","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}
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