The size of InGaN micro-LEDs is continuously decreasing to meet the demands of various emerging applications,especially in tiny micro-displays such as ARVR.However,the conventional pixel definition based on plasma etc...The size of InGaN micro-LEDs is continuously decreasing to meet the demands of various emerging applications,especially in tiny micro-displays such as ARVR.However,the conventional pixel definition based on plasma etching significantly damages the mesa sidewalls,leading to a severe reduction in efficiency as the micro-LED size decreases.This seriously impedes the development and application of micro-LEDs.In this work,we comprehensively explain the origin of micro-LED sidewall effects and corresponding physical models.Subsequently,we systematically review recent progress in micro-LED fabrication aiming at suppressing sidewall effects.Furthermore,we discuss advancements in micro-LED fabrication with"damage-free"techniques,which hold the potential to fundamentally address the issue of plasma damage in the micro-LED process.We believe this review will deepen the understanding of micro-LED sidewall effects and provide a better insight into the latest associated fabrication technologies for high-efficientInGaNmicro-LEDs.展开更多
This study pioneers a high-performance UV polarization-sensitive photodetector by ingeniously integrating noncentrosymmetric metal nanostructures into a graphene(Gr)/Al_(2)O_(3)/GaN heterojunction.Unlike conventional ...This study pioneers a high-performance UV polarization-sensitive photodetector by ingeniously integrating noncentrosymmetric metal nanostructures into a graphene(Gr)/Al_(2)O_(3)/GaN heterojunction.Unlike conventional approaches constrained by graphene's intrinsic isotropy or complex nanoscale patterning,our design introduces asymmetric metal architectures(E-/T-type) to artificially create directional anisotropy.These structures generate plasmon-enhanced localized electric fields that selectively amplify photogenerated carrier momentum under polarized UV light(325 nm),synergized with Fowler-Nordheim tunneling(FNT) across an atomically thin Al_(2)O_(3) barrier.The result is a breakthrough in performance:a record anisotropy ratio of 115.5(E-type,-2 V) and exceptional responsivity(97.7 A/W),surpassing existing graphene-based detectors by over an order of magnitude.Crucially,by systematically modulating metal geometry and density,we demonstrate a universal platform adaptable to diverse 2D/3D systems.This study provides a valuable reference for developing and practically applying photodetectors with higher anisotropy than ultraviolet polarization sensitivity.展开更多
Wide-bandgap semiconductors exhibit much larger energybandgaps than traditional semiconductors such as silicon,rendering them very promising to be applied in the fields of electronics and optoelectronics.Prominent exa...Wide-bandgap semiconductors exhibit much larger energybandgaps than traditional semiconductors such as silicon,rendering them very promising to be applied in the fields of electronics and optoelectronics.Prominent examples of semiconductors include SiC,GaN,ZnO,and diamond,which exhibitdistinctive characteristics such as elevated mobility and thermalconductivity.These characteristics facilitate the operation of awide range of devices,including energy-efficient bipolar junctiontransistors(BJTs)and metal-oxide-semiconductor field-effecttransistors(MOSFETs),as well as high-frequency high-electronmobility transistors(HEMTs)and optoelectronic components suchas light-emitting diodes(LEDs)and lasers.These semiconductorsare used in building integrated circuits(ICs)to facilitate theoperation of power electronics,computer devices,RF systems,andother optoelectronic advancements.These breakthroughs includevarious applications such as imaging,optical communication,andsensing.Among them,the field of power electronics has witnessedtremendous progress in recent years with the development of widebandgap(WBG)semiconductor devices,which is capable ofswitching large currents and voltages rapidly with low losses.However,it has been proven challenging to integrate these deviceswith silicon complementary metal oxide semiconductor(CMOS)logic circuits required for complex control functions.The monolithic integration of silicon CMOS with WBG devices increases thecomplexity of fabricating monolithically integrated smart integrated circuits(ICs).This review article proposes implementingCMOS logic directly on the WBG platform as a solution.However,achieving the CMOS functionalities with the adoption of WBGmaterials still remains a significant hurdle.This article summarizesthe research progress in the fabrication of integrated circuitsadopting various WBG materials ranging from SiC to diamond,with the goal of building future smart power ICs.展开更多
Semiconductor UV photonics research has emerged as one of the most heavily invested areas among semiconductor photonics research due to numerous crucial applications such as sterilization,sensing,curing,and communicat...Semiconductor UV photonics research has emerged as one of the most heavily invested areas among semiconductor photonics research due to numerous crucial applications such as sterilization,sensing,curing,and communication.The feature issue disseminates nine timely original research and two review papers from leading research groups and companies,covering most frontiers of the semiconductor UV photonics research,from epitaxy,device physics and design,nanostructures,fabrication,packaging,reliability,and application for light-emitting diodes,laser diodes,and photodetectors.展开更多
The traditional plasma etching process for defining micro-LED pixels could lead to significant sidewall damage.Defects near sidewall regions act as non-radiative recombination centers and paths for current leakage,sig...The traditional plasma etching process for defining micro-LED pixels could lead to significant sidewall damage.Defects near sidewall regions act as non-radiative recombination centers and paths for current leakage,significantly deteriorating device performance.In this study,we demonstrated a novel selective thermal oxidation(STO)method that allowed pixel definition without undergoing plasma damage and subsequent dielectric passivation.Thermal annealing in ambient air oxidized and reshaped the LED structure,such as p-layers and InGaN/GaN multiple quantum wells.Simultaneously,the pixel areas beneath the pre-deposited SiO_(2)layer were selectively and effectively protected.It was demonstrated that prolonged thermal annealing time enhanced the insulating properties of the oxide,significantly reducing LED leakage current.Furthermore,applying a thicker SiO_(2)protective layer minimized device resistance and boosted device efficiency effectively.Utilizing the STO method,InGaN green micro-LED arrays with 50-,30-,and 10-μm pixel sizes were manufactured and characterized.The results indicated that after 4 h of air annealing and with a 3.5-μm SiO_(2)protective layer,the 10-μm pixel array exhibited leakage currents density 1.2×10^(-6)A/cm^(2)at-10 V voltage and a peak on-wafer external quantum efficiency of~6.48%.This work suggests that the STO method could become an effective approach for future micro-LED manufacturing to mitigate adverse LED efficiency size effects due to the plasma etching and improve device efficiency.Micro-LEDs fabricated through the STO method can be applied to micro-displays,visible light communication,and optical interconnect-based memories.Almost planar pixel geometry will provide more possibilities for the monolithic integration of driving circuits with micro-LEDs.Moreover,the STO method is not limited to micro-LED fabrication and can be extended to design other III-nitride devices,such as photodetectors,laser diodes,high-electron-mobility transistors,and Schottky barrier diodes.展开更多
We demonstrate a neural network capable of designing on-demand multiple symmetry-protected bound states in the continuum(BICs)in freeform structures with predefined symmetry.The latent representation of the freeform s...We demonstrate a neural network capable of designing on-demand multiple symmetry-protected bound states in the continuum(BICs)in freeform structures with predefined symmetry.The latent representation of the freeform structures allows the tuning of the geometry in a differentiable,continuous way.We show the rich band inversion and accidental degeneracy in these freeform structures by interacting with the latent representation directly.Moreover,a high design accuracy is demonstrated for arbitrary control of multiple BIC frequencies by using a photonic property readout network to interpret the latent representation.展开更多
A nanowire （NW） structure provides an alternative scheme for deep ultraviolet light emitting diodes （DUV-LEDs） that promises high material quality and better light extraction efficiency （LEE）. In this report, we...A nanowire （NW） structure provides an alternative scheme for deep ultraviolet light emitting diodes （DUV-LEDs） that promises high material quality and better light extraction efficiency （LEE）. In this report, we investigate the influence of the tapering angle of closely packed AIGaN NWs, which is found to exist naturally in molecular beam epitaxy （MBE） grown NW structures, on the LEE of NW DUV-LEDs. It is observed that, by having a small tapering angle, the vertical extraction is greatly enhanced for both transverse magnetic （TM） and transverse elec- tric （TE） polarizations. Most notably, the vertical extraction of TM emission increased from 4.8% to 24.3%, which makes the LEE reasonably large to achieve high-performance DUV-LEDs. This is because the breaking of symmetry in the vertical direction changes the propagation of the light significantly to allow more coupling into radiation modes. Finally, we introduce errors to the NW positions to show the advantages of the tapered NW structures can be projected to random closely packed NW arrays. The results obtained in this paper can provide guidelines for designing efficient NW DUV-LEDs.展开更多
Connected-annular-rods photonic crystals(CARPCs) in both triangular and square lattices are proposed to enhance the two-dimensional complete photonic bandgap(CPBG) for chalcogenide material systems with moderate refra...Connected-annular-rods photonic crystals(CARPCs) in both triangular and square lattices are proposed to enhance the two-dimensional complete photonic bandgap(CPBG) for chalcogenide material systems with moderate refractive index contrast. For the typical chalcogenide-glass–air system with an index contrast of 2.8:1, the optimized square lattice CARPC exhibits a significantly larger normalized CPBG of about 13.50%, though the use of triangular lattice CARPC is unable to enhance the CPBG. It is almost twice as large as our previously reported result [IEEE J. Sel. Top. Quantum Electron. 22, 4900108(2016)]. Moreover, the CPBG of the square-lattice CARPC could remain until an index contrast as low as 2.24:1. The result not only favors wideband CPBG applications for index contrast systems near 2.8:1, but also makes various optical applications that are dependent on CPBG possible for more widely refractive index contrast systems.展开更多
We report on the carrier dynamic and electronic structure investigations on AlGaN-based deep-ultraviolet multiple quantum wells (MQWs)with lateral polarity domains.The localized potential maximum is predicted near the...We report on the carrier dynamic and electronic structure investigations on AlGaN-based deep-ultraviolet multiple quantum wells (MQWs)with lateral polarity domains.The localized potential maximum is predicted near the domain boundaries by first-principle calculation,suggesting carrier localization and efficient radiative recombination.More importantly,lateral band diagrams of the MQWs are proposed based on electron affinities and valance band levels calculated from ultraviolet(UV)photoelectron spectroscopy.The proposed lateral band diagram is further demonstrated by surface potential distribution collected by Kelvin probe microscopy and the density-of-state calculation of energy bands.This work illustrates that lateral polarity structures are playing essential roles in the electronic properties of II nitride photonic devices and may provide novel perspective in the realization of high-efficiency UV emitters.展开更多
Surface potentials in the vicinity of V-pits(cone bottom) and U-pits(blunt bottom) on epitaxial GaN surface have been systematically studied using ultraviolet(UV) light-assisted Kelvin probe force microscopy(KPFM). Th...Surface potentials in the vicinity of V-pits(cone bottom) and U-pits(blunt bottom) on epitaxial GaN surface have been systematically studied using ultraviolet(UV) light-assisted Kelvin probe force microscopy(KPFM). The band structure models are established to understand variation of the surface potentials at the pits and planar surface with and without UV light. The photo-generated carrier behavior at the pit defects is studied. According to the surface potential results, it can be deduced that the carrier distributions around the V-and U-pits are uneven. In dark, the electron concentration at the bottom of V-pit(30 n_0) and Upit(15 n_0) are higher than that at planar surface(n_0). Under UV light, for V-pit, the electron concentration at the cone bottom(4.93×10^(11) n_0) is lower than that at the surrounding planar surface(5.68×10^(13) n_0). For U-pit, the electron concentration at the blunt bottom is 1.35×10^(12) n_0, which is lower than that at the surrounding planar surface(6.13×10^(13) n_0). The non-equilibrium electron concentrations at different locations are calculated. Based on the non-equilibrium electron concentration, it can be concluded that the carrier recombination rate at pit defects is higher than that at planar surface.展开更多
Semiconductor materials provide a compelling platform for quantum technologies(QT).However,identifying promising material hosts among the plethora of candidates is a major challenge.Therefore,we have developed a frame...Semiconductor materials provide a compelling platform for quantum technologies(QT).However,identifying promising material hosts among the plethora of candidates is a major challenge.Therefore,we have developed a framework for the automated discovery of semiconductor platforms for QT using material informatics and machine learning methods.Different approaches were implemented to label data for training the supervised machine learning(ML)algorithms logistic regression,decision trees,random forests and gradient boosting.We find that an empirical approach relying exclusively on findings from the literature yields a clear separation between predicted suitable and unsuitable candidates.In contrast to expectations from the literature focusing on band gap and ionic character as important properties for QT compatibility,the ML methods highlight features related to symmetry and crystal structure,including bond length,orientation and radial distribution,as influential when predicting a material as suitable for QT.展开更多
基金The authors would like to acknowledge the support of KAUST Baseline Fund BAS/1/1664-01-01,Transition Award in Semiconductors,Award No.FCC/1/5939,OpportunityFundURF/1/5557-01-01.
文摘The size of InGaN micro-LEDs is continuously decreasing to meet the demands of various emerging applications,especially in tiny micro-displays such as ARVR.However,the conventional pixel definition based on plasma etching significantly damages the mesa sidewalls,leading to a severe reduction in efficiency as the micro-LED size decreases.This seriously impedes the development and application of micro-LEDs.In this work,we comprehensively explain the origin of micro-LED sidewall effects and corresponding physical models.Subsequently,we systematically review recent progress in micro-LED fabrication aiming at suppressing sidewall effects.Furthermore,we discuss advancements in micro-LED fabrication with"damage-free"techniques,which hold the potential to fundamentally address the issue of plasma damage in the micro-LED process.We believe this review will deepen the understanding of micro-LED sidewall effects and provide a better insight into the latest associated fabrication technologies for high-efficientInGaNmicro-LEDs.
基金National Natural Science Foundation of China(62375090, 62374062, 52002135)Natural Science Foundation of Guangdong Province of China(2023B1515120071)+2 种基金Science and Technology Program of Guangdong Province of China (2023A0505050131,2022A0505050066, 2024A1515011081)Characteristic Innovation Project of Universities in Guangdong Province(2023KTSCX028)Science and Technology Program of Guangzhou,China (2024A04J6456)
文摘This study pioneers a high-performance UV polarization-sensitive photodetector by ingeniously integrating noncentrosymmetric metal nanostructures into a graphene(Gr)/Al_(2)O_(3)/GaN heterojunction.Unlike conventional approaches constrained by graphene's intrinsic isotropy or complex nanoscale patterning,our design introduces asymmetric metal architectures(E-/T-type) to artificially create directional anisotropy.These structures generate plasmon-enhanced localized electric fields that selectively amplify photogenerated carrier momentum under polarized UV light(325 nm),synergized with Fowler-Nordheim tunneling(FNT) across an atomically thin Al_(2)O_(3) barrier.The result is a breakthrough in performance:a record anisotropy ratio of 115.5(E-type,-2 V) and exceptional responsivity(97.7 A/W),surpassing existing graphene-based detectors by over an order of magnitude.Crucially,by systematically modulating metal geometry and density,we demonstrate a universal platform adaptable to diverse 2D/3D systems.This study provides a valuable reference for developing and practically applying photodetectors with higher anisotropy than ultraviolet polarization sensitivity.
基金supported by KAUST BaselineFund:BAS/1/1664-01-01,KAUST Near-term Grand Challenge Fund:REI/1/4999-01-01,KAUST Impact Acceleration Fund:REI/1/5124-01-01.
文摘Wide-bandgap semiconductors exhibit much larger energybandgaps than traditional semiconductors such as silicon,rendering them very promising to be applied in the fields of electronics and optoelectronics.Prominent examples of semiconductors include SiC,GaN,ZnO,and diamond,which exhibitdistinctive characteristics such as elevated mobility and thermalconductivity.These characteristics facilitate the operation of awide range of devices,including energy-efficient bipolar junctiontransistors(BJTs)and metal-oxide-semiconductor field-effecttransistors(MOSFETs),as well as high-frequency high-electronmobility transistors(HEMTs)and optoelectronic components suchas light-emitting diodes(LEDs)and lasers.These semiconductorsare used in building integrated circuits(ICs)to facilitate theoperation of power electronics,computer devices,RF systems,andother optoelectronic advancements.These breakthroughs includevarious applications such as imaging,optical communication,andsensing.Among them,the field of power electronics has witnessedtremendous progress in recent years with the development of widebandgap(WBG)semiconductor devices,which is capable ofswitching large currents and voltages rapidly with low losses.However,it has been proven challenging to integrate these deviceswith silicon complementary metal oxide semiconductor(CMOS)logic circuits required for complex control functions.The monolithic integration of silicon CMOS with WBG devices increases thecomplexity of fabricating monolithically integrated smart integrated circuits(ICs).This review article proposes implementingCMOS logic directly on the WBG platform as a solution.However,achieving the CMOS functionalities with the adoption of WBGmaterials still remains a significant hurdle.This article summarizesthe research progress in the fabrication of integrated circuitsadopting various WBG materials ranging from SiC to diamond,with the goal of building future smart power ICs.
文摘Semiconductor UV photonics research has emerged as one of the most heavily invested areas among semiconductor photonics research due to numerous crucial applications such as sterilization,sensing,curing,and communication.The feature issue disseminates nine timely original research and two review papers from leading research groups and companies,covering most frontiers of the semiconductor UV photonics research,from epitaxy,device physics and design,nanostructures,fabrication,packaging,reliability,and application for light-emitting diodes,laser diodes,and photodetectors.
基金support of KAUST Baseline Fund BAS/1/1664-01-01,KAUST Competitive Research Grants URF/1/3437-01-01,URF/1/3771-01-01KAUST Near-term Grand Challenge Fund REI/1/4999-01-01KAUST Impact Acceleration Fund REI/1/5124-01-01.
文摘The traditional plasma etching process for defining micro-LED pixels could lead to significant sidewall damage.Defects near sidewall regions act as non-radiative recombination centers and paths for current leakage,significantly deteriorating device performance.In this study,we demonstrated a novel selective thermal oxidation(STO)method that allowed pixel definition without undergoing plasma damage and subsequent dielectric passivation.Thermal annealing in ambient air oxidized and reshaped the LED structure,such as p-layers and InGaN/GaN multiple quantum wells.Simultaneously,the pixel areas beneath the pre-deposited SiO_(2)layer were selectively and effectively protected.It was demonstrated that prolonged thermal annealing time enhanced the insulating properties of the oxide,significantly reducing LED leakage current.Furthermore,applying a thicker SiO_(2)protective layer minimized device resistance and boosted device efficiency effectively.Utilizing the STO method,InGaN green micro-LED arrays with 50-,30-,and 10-μm pixel sizes were manufactured and characterized.The results indicated that after 4 h of air annealing and with a 3.5-μm SiO_(2)protective layer,the 10-μm pixel array exhibited leakage currents density 1.2×10^(-6)A/cm^(2)at-10 V voltage and a peak on-wafer external quantum efficiency of~6.48%.This work suggests that the STO method could become an effective approach for future micro-LED manufacturing to mitigate adverse LED efficiency size effects due to the plasma etching and improve device efficiency.Micro-LEDs fabricated through the STO method can be applied to micro-displays,visible light communication,and optical interconnect-based memories.Almost planar pixel geometry will provide more possibilities for the monolithic integration of driving circuits with micro-LEDs.Moreover,the STO method is not limited to micro-LED fabrication and can be extended to design other III-nitride devices,such as photodetectors,laser diodes,high-electron-mobility transistors,and Schottky barrier diodes.
基金King Abdullah University of Science and Technology Baseline Fund(BAS/1/1664-01-01)Competitive Research Grants(URF/1/3437-01-01,URF/1/3771-01-01).
文摘We demonstrate a neural network capable of designing on-demand multiple symmetry-protected bound states in the continuum(BICs)in freeform structures with predefined symmetry.The latent representation of the freeform structures allows the tuning of the geometry in a differentiable,continuous way.We show the rich band inversion and accidental degeneracy in these freeform structures by interacting with the latent representation directly.Moreover,a high design accuracy is demonstrated for arbitrary control of multiple BIC frequencies by using a photonic property readout network to interpret the latent representation.
基金King Abdullah University of Science and Technology(KAUST)(KAUST Baseline Fund BAS/1/1614-01-01,KAUST Baseline Fund BAS/1/1664-01-01,KAUST Equipment Fund BAS/1/1664-01-07)National Natural Science Foundation of China(NSFC)(61774065)
文摘A nanowire （NW） structure provides an alternative scheme for deep ultraviolet light emitting diodes （DUV-LEDs） that promises high material quality and better light extraction efficiency （LEE）. In this report, we investigate the influence of the tapering angle of closely packed AIGaN NWs, which is found to exist naturally in molecular beam epitaxy （MBE） grown NW structures, on the LEE of NW DUV-LEDs. It is observed that, by having a small tapering angle, the vertical extraction is greatly enhanced for both transverse magnetic （TM） and transverse elec- tric （TE） polarizations. Most notably, the vertical extraction of TM emission increased from 4.8% to 24.3%, which makes the LEE reasonably large to achieve high-performance DUV-LEDs. This is because the breaking of symmetry in the vertical direction changes the propagation of the light significantly to allow more coupling into radiation modes. Finally, we introduce errors to the NW positions to show the advantages of the tapered NW structures can be projected to random closely packed NW arrays. The results obtained in this paper can provide guidelines for designing efficient NW DUV-LEDs.
基金National Natural Science Foundation of China(NSFC)(11504435,11147014)Natural Science Foundation of Hubei Province,China(2013CFA052)+1 种基金King Abdullah University of Science and Technology(KAUST)(Baseline BAS/1/1664-01-01)Fundamental Research Funds for the Central Universities,South-Central University for Nationalities,China(CZY18001)
文摘Connected-annular-rods photonic crystals(CARPCs) in both triangular and square lattices are proposed to enhance the two-dimensional complete photonic bandgap(CPBG) for chalcogenide material systems with moderate refractive index contrast. For the typical chalcogenide-glass–air system with an index contrast of 2.8:1, the optimized square lattice CARPC exhibits a significantly larger normalized CPBG of about 13.50%, though the use of triangular lattice CARPC is unable to enhance the CPBG. It is almost twice as large as our previously reported result [IEEE J. Sel. Top. Quantum Electron. 22, 4900108(2016)]. Moreover, the CPBG of the square-lattice CARPC could remain until an index contrast as low as 2.24:1. The result not only favors wideband CPBG applications for index contrast systems near 2.8:1, but also makes various optical applications that are dependent on CPBG possible for more widely refractive index contrast systems.
基金National Key Researchand Development Program of China(2016YFB0400802)+2 种基金National Natural Science Foundation of China(61704176,61974149)Key Research and Development Program of Zhejiang Province(2019C01080,2020C01145)Ningbo Innovation 2025 Major Project(2018B10088,2019B10121).
文摘We report on the carrier dynamic and electronic structure investigations on AlGaN-based deep-ultraviolet multiple quantum wells (MQWs)with lateral polarity domains.The localized potential maximum is predicted near the domain boundaries by first-principle calculation,suggesting carrier localization and efficient radiative recombination.More importantly,lateral band diagrams of the MQWs are proposed based on electron affinities and valance band levels calculated from ultraviolet(UV)photoelectron spectroscopy.The proposed lateral band diagram is further demonstrated by surface potential distribution collected by Kelvin probe microscopy and the density-of-state calculation of energy bands.This work illustrates that lateral polarity structures are playing essential roles in the electronic properties of II nitride photonic devices and may provide novel perspective in the realization of high-efficiency UV emitters.
基金supported by the National Key R&D Program of China(Grant No.2016YFB0400101)the National Science Fund for Distinguished Young Scholars(Grant No.61725403)+8 种基金the National Natural Science Foundation of China(Grant Nos.61574142,61322406,61704171,and11705206)the National Natural Science Foundation of China(Grant No.61774065)the Key Program of the International Partnership Program of Chinese Academy of Sciences(Grant No.181722KYSB20160015)the Special Project for Inter-government Collaboration of the State Key Research and Development Program(Grant No.2016YFE0118400)the Science and Technology Service Network Initiative of the Chinese Academy of Sciences,the Jilin Provincial Science&Technology Department(Grant No.20180201026GX)the CAS Interdisciplinary Innovation Team,and the Youth Innovation Promotion Association of Chinese Academy of Sciences(Grant No.2015171)the support of King Abdullah University of Science and Technology(KAUST)Baseline(Grant No.BAS/1/1664-01-01)the Competitive Research(Grant No.URF/1/3437-01-01)Gulf Cooperation Council(GCC)Research Council(Grant No.REP/1/3189-01-01)
文摘Surface potentials in the vicinity of V-pits(cone bottom) and U-pits(blunt bottom) on epitaxial GaN surface have been systematically studied using ultraviolet(UV) light-assisted Kelvin probe force microscopy(KPFM). The band structure models are established to understand variation of the surface potentials at the pits and planar surface with and without UV light. The photo-generated carrier behavior at the pit defects is studied. According to the surface potential results, it can be deduced that the carrier distributions around the V-and U-pits are uneven. In dark, the electron concentration at the bottom of V-pit(30 n_0) and Upit(15 n_0) are higher than that at planar surface(n_0). Under UV light, for V-pit, the electron concentration at the cone bottom(4.93×10^(11) n_0) is lower than that at the surrounding planar surface(5.68×10^(13) n_0). For U-pit, the electron concentration at the blunt bottom is 1.35×10^(12) n_0, which is lower than that at the surrounding planar surface(6.13×10^(13) n_0). The non-equilibrium electron concentrations at different locations are calculated. Based on the non-equilibrium electron concentration, it can be concluded that the carrier recombination rate at pit defects is higher than that at planar surface.
基金The work of L.V.and M.E.B.was supported by the Research Council of Norway and the University of Oslo through the frontier research projects FUNDAMeNT(no.251131)and QuTe(no.325573)The work of M.E.B.was supported by an ETH Zurich Postdoctoral Fellowship+1 种基金The work of M.H.J.was supported by the U.S.Department of Energy,Office of Science,office of Nuclear Physics under grant No.DE-SC0021152 and U.S.National Science Foundation Grants Nos.PHY-1404159 and PHY-2013047The work of SGWL andøSS was supported by the Norwegian Directorate for International Cooperation and Quality Enhancement in Higher Education(DIKU)which supports the Center for Computing in Science Education(CCSE).
文摘Semiconductor materials provide a compelling platform for quantum technologies(QT).However,identifying promising material hosts among the plethora of candidates is a major challenge.Therefore,we have developed a framework for the automated discovery of semiconductor platforms for QT using material informatics and machine learning methods.Different approaches were implemented to label data for training the supervised machine learning(ML)algorithms logistic regression,decision trees,random forests and gradient boosting.We find that an empirical approach relying exclusively on findings from the literature yields a clear separation between predicted suitable and unsuitable candidates.In contrast to expectations from the literature focusing on band gap and ionic character as important properties for QT compatibility,the ML methods highlight features related to symmetry and crystal structure,including bond length,orientation and radial distribution,as influential when predicting a material as suitable for QT.
