Al_(1-x)In_(x)N, a Ⅲ-nitride semiconductor material, is currently of great research interest due to its remarkable physical properties and chemical stability. When the Al and In compositions are tuned, its band-gap e...Al_(1-x)In_(x)N, a Ⅲ-nitride semiconductor material, is currently of great research interest due to its remarkable physical properties and chemical stability. When the Al and In compositions are tuned, its band-gap energy varies from 0.7 eV to 6.2 eV, which shows great potential for application in photodetectors. Here, we report the fabrication and performance evaluation of integrated Al_(1-x)In_(x)N on a free-standing GaN substrate through direct radio-frequency magnetron sputtering.The optical properties of Al_(1-x)In_(x)N will be enhanced by the polarization effect of a heterostructure composed of Al_(1-x)In_(x)N and other Ⅲ-nitride materials. An Al_(1-x)In_(x)N/Ga N visible-light photodetector was prepared by semiconductor fabrication technologies such as lithography and metal deposition. The highest photoresponsivity achieved was 1.52 A·W^(-1)under 365 nm wavelength illumination and the photodetector was determined to have the composition Al0.75In0.25N/GaN.A rise time of 0.55 s was observed after transient analysis of the device. The prepared Al_(1-x)In_(x)N visible-light photodetector had a low dark current, high photoresponsivity and fast response speed. By promoting a low-cost, simple fabrication method,this study expands the application of ternary alloy Al_(1-x)In_(x)N visible-light photodetectors in optical communication.展开更多
In this study,a galliumnitride(GaN)substrate and its 15μmepitaxial layer were entirely grown by adopting the hydride vapor phase epitaxy(HVPE)technique.To enhance the breakdown voltage(VBR)of vertical GaN-on-GaN Scho...In this study,a galliumnitride(GaN)substrate and its 15μmepitaxial layer were entirely grown by adopting the hydride vapor phase epitaxy(HVPE)technique.To enhance the breakdown voltage(VBR)of vertical GaN-on-GaN Schottky barrier diodes(SBDs),a dual ion coimplantation of carbon and heliumwas employed to create the edge termination.The resulting devices exhibited a low turn-on voltage of 0.55 V,a high Ion/Ioff ratio of approximately 109,and a lowspecific onresistance of 1.93 mU cm^(2).When the ion implantation edge was terminated,the maximumVBR of the devices reached 1575 V,with an average improvement of 126%.These devices demonstrated a high figure of merit(FOM)of 1.28 GW cm^(-2) and showed excellent reliability during pulse stress testing.展开更多
Introducing voids into AlN layer at a certain height using a simple method is meaningful but challenging.In this work,the AlN/sapphire template with AlN interlayer structure was designed and grown by metal-organic che...Introducing voids into AlN layer at a certain height using a simple method is meaningful but challenging.In this work,the AlN/sapphire template with AlN interlayer structure was designed and grown by metal-organic chemical vapor deposition.Then,the AlN template was annealed at 1700℃for an hour to introduce the voids.It was found that voids were formed in the AlN layer after high-temperature annealing and they were mainly distributed around the AlN interlayer.Meanwhile,the dislocation density of the AlN template decreased from 5.26×10^(9)cm^(-2)to 5.10×10^(8)cm^(-2).This work provides a possible method to introduce voids into AlN layer at a designated height,which will benefit the design of AlN-based devices.展开更多
AlGaN/GaN heterojunction field-effect transistors(HFETs)with p-GaN cap layer are developed for normally-off operation,in which an in-situ grown AlN layer is utilized as the gate insulator.Compared with the SiNxgate in...AlGaN/GaN heterojunction field-effect transistors(HFETs)with p-GaN cap layer are developed for normally-off operation,in which an in-situ grown AlN layer is utilized as the gate insulator.Compared with the SiNxgate insulator,the AlN/p-GaN interface presents a more obvious energy band bending and a wider depletion region,which helps to positively shift the threshold voltage.In addition,the relatively large conduction band offset of AlN/p-GaN is beneficial to suppress the gate leakage current and enhance the gate breakdown voltage.Owing to the introduction of AlN layer,normally-off p-GaN capped AlGaN/GaN HFET with a threshold voltage of 4 V and a gate swing of 13 V is realized.Furthermore,the field-effect mobility is approximately 1500 cm^(2)·V^(-1)·s^(-1)in the 2DEG channel,implying a good device performance.展开更多
Background To compare the safety and efficacy of pipeline embolization device(PED)and Tubridge flow diverter(TFD)for unruptured posterior circulation aneurysms.Methods Posterior aneurysm patients treated with PED or T...Background To compare the safety and efficacy of pipeline embolization device(PED)and Tubridge flow diverter(TFD)for unruptured posterior circulation aneurysms.Methods Posterior aneurysm patients treated with PED or TFD between January,2019,and December,2021,were retrospectively reviewed.Patients’demographics,aneurysm characteristics,treatment details,complications,and follow-up information were collected.The procedural-related complications and angiographic and clinical outcome were compared.Results A total of 107 patients were involved;PED was applied for 55 patients and TFD for 52 patients.A total of 9(8.4%)procedural-related complications occurred,including 4(7.3%)in PED group and 5(9.6%)in TFD group.During a mean of 10.3-month angiographic follow-up for 81 patients,complete occlusion was achieved in 35(85.4%)patients in PED group and 30(75.0%)in TFD group.The occlusion rate of PED group is slightly higher than that of TFD group.A mean of 25.0-month clinical follow-up for 107 patients showed that favorable clinical outcome was achieved in 53(96.4%)patients in PED group and 50(96.2%)patients in TFD group,respectively.No statistical difference was found in terms of procedural-related complications(p=0.737),occlusion rate(p=0.241),and favorable clinical outcome(0.954)between groups.Conclusions The current study found no difference in complication,occlusion,and clinical outcome between PED and TFD for unruptured PCAs.展开更多
The high density of defects induced by large strains in largely mismatched heteroepitaxy systems, such as AlN and GaN, because of the large lattice and thermal mismatch between substrates and epilayers is the bottlene...The high density of defects induced by large strains in largely mismatched heteroepitaxy systems, such as AlN and GaN, because of the large lattice and thermal mismatch between substrates and epilayers is the bottleneck problem. Graphene-assisted van der Waals(vdW) heteroepitaxy offers a new opportunity to resolve this problem. However, it suffers from the difficulty of nucleation. Here we theoretically assess the effects of five 2D materials for vdW heteroepitaxy of AlN and GaN, including graphene, hBN, MoS2, gC3N, and gC3N4, and provide physical insights using first-principle calculations. MoS2 and gC3N exhibit significant potential to overcome the shortcomings of graphene owing to their appropriate binding strengths and Al(or Ga)diffusion barriers. Moreover, the interface behavior between the epilayers and the substrates are carefully analyzed. Our findings are helpful not only for obtaining high-quality AlN and GaN films but also for developing new criterions to discover effective 2D materials for vdW heteroepitaxy.展开更多
This paper proposes a micro-LED backlight module with a distributed Bragg reflector(DBR) structure to achieve excellent micro-LED backlight module quality and uses deep reinforcement learning(DRL) architecture for opt...This paper proposes a micro-LED backlight module with a distributed Bragg reflector(DBR) structure to achieve excellent micro-LED backlight module quality and uses deep reinforcement learning(DRL) architecture for optical design. In the DRL architecture, to solve the computing environment problems of the two extreme structures of micro-scale and macro-scale, this paper proposes an environment control agent and virtual-realistic workflow to ensure that the design environment parameters are highly correlated with experimental results. This paper successfully designed a micro-LED backlight module with a DBR structure by the abovementioned methods.The micro-LED backlight module with a DBR structure improves the uniformity performance by 32% compared with the micro-LED backlight module without DBR, and the design calculation time required by the DRL method is only 17.9% of the traditional optical simulation.展开更多
With the increasing demand for high integration and multi-color photodetection for both military and civilian applications, the research of multi-wavelength detectors has become a new research hotspot. However, curren...With the increasing demand for high integration and multi-color photodetection for both military and civilian applications, the research of multi-wavelength detectors has become a new research hotspot. However, current research has been mainly in visible dual-or multi-wavelength detectors, while integration of both visible light and ultraviolet(UV) dual-wavelength detectors has rarely been studied. In this work, large-scale and high-quality monolayer MoS2 was grown by the chemical vapor deposition method on transparent free-standing GaN substrate. Monolithic integration of MoS2-based visible detectors and GaN-based UV detectors was demonstrated using common semiconductor fabrication technologies such as photolithography, argon plasma etching, and metal deposition. High performance of a 280 nm and 405 nm dual-wavelength photodetector was realized.The responsivity of the UV detector reached 172.12 A/W, while that of the visible detector reached 17.5 A/W.Meanwhile, both photodetectors achieved high photocurrent gain, high external quantum efficiency, high normalized detection rate, and low noise equivalent power. Our study extends the future application of dual-wavelength detectors for image sensing and optical communication.展开更多
Background:Deregulation of miRNA-21 expression has been reported to be associated with vascular smooth muscle behavior and cytoskeletal stability.This study is aimed to investigate the density of serum miRNA-21 in pat...Background:Deregulation of miRNA-21 expression has been reported to be associated with vascular smooth muscle behavior and cytoskeletal stability.This study is aimed to investigate the density of serum miRNA-21 in patients with different phases of intracranial aneurysms(IAs)and explore its warning function for IA rupture.Methods:A total of 16 in 200 IA patients were selected and categorized into 4 groups based on the phase of IA.Microarray study was carried out using serum miRNA and differentially expressed miRNAs were identified.Another 24 samples from a cohort of 360 patients were added and real-time polymerase chain reaction(RT-PCR)was performed on expanded sample size(n=40)for miRNA-21 validation.Potential gene targets of miRNA-21 were screened out from Gene Ontology(GO)database and literatures.Results:Microarray study identified 77 miRNAs with significantly different expression levels between experimental groups and the control group.RT-PCR assays validated significant downregulation of miRNA-21 in experimental groups,among which miRNA-21 expression level of daughter aneurysm group decreased the most.Bioinformatic analyses revealed that several target genes related with miRNA-21 may be involved in IA formation and rupture.Conclusions:This study suggested that miRNA-21 had a protective effect for intracranial vascular wall against remodeling and warning function for intracranial aneurysm rupture.Significant suppression of serum miRNA-21 in IA patients may provide diagnostic clues for aneurysm rupture and guide clinical intervention.展开更多
Strain regulation as an effective way to enhance the photoelectric properties of two dimensional(2D)transition metal dichalcogenides has been widely employed to improve the performance of photovoltaic devices.In this ...Strain regulation as an effective way to enhance the photoelectric properties of two dimensional(2D)transition metal dichalcogenides has been widely employed to improve the performance of photovoltaic devices.In this work,tensile strain was introduced in multilayer MoS2 grown on GaN by depositing 3 nm of Al2O3 on the surface.The temperature dependent Raman spectrum shows that the thermal stability of MoS2 is improved by Al2O3.Theoretical simulations confirmed the existence of tensile strain on MoS2 covered with Al2O3,and the bandgap and electron effective mass of six layers of MoS2 decreased due to tensile strain,which resulted in an increase of electron mobility.Due to the tensile strain ffect,the photodetector with the Al2O3 stress liner achieved better performance under the illumination of 365 nm wavelength,including a higher responsivity of 24.6 A/W,photoconductive gain of 520,and external quantum fficiency of 8381%,which are more than twice the corresponding values of photodetectors without Al2O3.Our work provides an effective technical way for improving the performance of 2D material photodetectors.展开更多
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 61974144, 62004127, and 12074263)Key-Area Research and Development Program of Guangdong Province (Grant Nos. 2020B010174003 and 2020B010169001)+2 种基金Guangdong Science Foundation for Distinguished Young Scholars (Grant No. 2022B1515020073)the Science and Technology Foundation of Shenzhen (Grant No. JSGG20191129114216474)the Open Project of State Key Laboratory of Functional Materials for Informatics。
文摘Al_(1-x)In_(x)N, a Ⅲ-nitride semiconductor material, is currently of great research interest due to its remarkable physical properties and chemical stability. When the Al and In compositions are tuned, its band-gap energy varies from 0.7 eV to 6.2 eV, which shows great potential for application in photodetectors. Here, we report the fabrication and performance evaluation of integrated Al_(1-x)In_(x)N on a free-standing GaN substrate through direct radio-frequency magnetron sputtering.The optical properties of Al_(1-x)In_(x)N will be enhanced by the polarization effect of a heterostructure composed of Al_(1-x)In_(x)N and other Ⅲ-nitride materials. An Al_(1-x)In_(x)N/Ga N visible-light photodetector was prepared by semiconductor fabrication technologies such as lithography and metal deposition. The highest photoresponsivity achieved was 1.52 A·W^(-1)under 365 nm wavelength illumination and the photodetector was determined to have the composition Al0.75In0.25N/GaN.A rise time of 0.55 s was observed after transient analysis of the device. The prepared Al_(1-x)In_(x)N visible-light photodetector had a low dark current, high photoresponsivity and fast response speed. By promoting a low-cost, simple fabrication method,this study expands the application of ternary alloy Al_(1-x)In_(x)N visible-light photodetectors in optical communication.
基金supported by the GuangdongMajor Project of Basic and Applied Basic Research(2023B0303000012)Guangdong Science Foundation for Distinguished Young Scholars(2022B1515020073)Shenzhen Science and Technology Program(JCYJ20220818102809020).
文摘In this study,a galliumnitride(GaN)substrate and its 15μmepitaxial layer were entirely grown by adopting the hydride vapor phase epitaxy(HVPE)technique.To enhance the breakdown voltage(VBR)of vertical GaN-on-GaN Schottky barrier diodes(SBDs),a dual ion coimplantation of carbon and heliumwas employed to create the edge termination.The resulting devices exhibited a low turn-on voltage of 0.55 V,a high Ion/Ioff ratio of approximately 109,and a lowspecific onresistance of 1.93 mU cm^(2).When the ion implantation edge was terminated,the maximumVBR of the devices reached 1575 V,with an average improvement of 126%.These devices demonstrated a high figure of merit(FOM)of 1.28 GW cm^(-2) and showed excellent reliability during pulse stress testing.
基金the National Key Research and Development Program of China(Grant No.2017YFB0404100)the National Natural Science Foundation of China(Grant Nos.61827813,61974144,and 62004127)+2 种基金the Key Research Program of the Chinese Academy of Sciences(Grant No.XDPB22)the Key-Area Research and Development Program of Guangdong Province,China(Grant Nos.2020B010169001 and 2020B010174003)the Science and Technology Foundation of Shenzhen(Grant No.JSGG20191129114216474)。
文摘Introducing voids into AlN layer at a certain height using a simple method is meaningful but challenging.In this work,the AlN/sapphire template with AlN interlayer structure was designed and grown by metal-organic chemical vapor deposition.Then,the AlN template was annealed at 1700℃for an hour to introduce the voids.It was found that voids were formed in the AlN layer after high-temperature annealing and they were mainly distributed around the AlN interlayer.Meanwhile,the dislocation density of the AlN template decreased from 5.26×10^(9)cm^(-2)to 5.10×10^(8)cm^(-2).This work provides a possible method to introduce voids into AlN layer at a designated height,which will benefit the design of AlN-based devices.
基金Supported by the National Natural Science Foundation of China(Grant No.61904207)scientific research support foundation for introduced high-level talents of Shenyang Ligong University(Grant No.1010147000914)the Natural Science Foundation of Sichuan Province,China(Grant No.2022NSFSC0886)
文摘AlGaN/GaN heterojunction field-effect transistors(HFETs)with p-GaN cap layer are developed for normally-off operation,in which an in-situ grown AlN layer is utilized as the gate insulator.Compared with the SiNxgate insulator,the AlN/p-GaN interface presents a more obvious energy band bending and a wider depletion region,which helps to positively shift the threshold voltage.In addition,the relatively large conduction band offset of AlN/p-GaN is beneficial to suppress the gate leakage current and enhance the gate breakdown voltage.Owing to the introduction of AlN layer,normally-off p-GaN capped AlGaN/GaN HFET with a threshold voltage of 4 V and a gate swing of 13 V is realized.Furthermore,the field-effect mobility is approximately 1500 cm^(2)·V^(-1)·s^(-1)in the 2DEG channel,implying a good device performance.
基金supported by the National Natural Science Foundation of China(Grant Number 82171289)the Beijing Gold-Bridge Project(Grant number ZZ21060)
文摘Background To compare the safety and efficacy of pipeline embolization device(PED)and Tubridge flow diverter(TFD)for unruptured posterior circulation aneurysms.Methods Posterior aneurysm patients treated with PED or TFD between January,2019,and December,2021,were retrospectively reviewed.Patients’demographics,aneurysm characteristics,treatment details,complications,and follow-up information were collected.The procedural-related complications and angiographic and clinical outcome were compared.Results A total of 107 patients were involved;PED was applied for 55 patients and TFD for 52 patients.A total of 9(8.4%)procedural-related complications occurred,including 4(7.3%)in PED group and 5(9.6%)in TFD group.During a mean of 10.3-month angiographic follow-up for 81 patients,complete occlusion was achieved in 35(85.4%)patients in PED group and 30(75.0%)in TFD group.The occlusion rate of PED group is slightly higher than that of TFD group.A mean of 25.0-month clinical follow-up for 107 patients showed that favorable clinical outcome was achieved in 53(96.4%)patients in PED group and 50(96.2%)patients in TFD group,respectively.No statistical difference was found in terms of procedural-related complications(p=0.737),occlusion rate(p=0.241),and favorable clinical outcome(0.954)between groups.Conclusions The current study found no difference in complication,occlusion,and clinical outcome between PED and TFD for unruptured PCAs.
基金supported by the National Natural Science Fund for Distinguished Young Scholars(Grant No.61725403)the Special Fund for Research on National Major Research Instruments(Grant No.61827813)+6 种基金the National Natural Science Foundation of China(Grant Nos.61874118,61834008,and 61804152)the Key Program of the International Partnership Program of CAS(Grant No.181722KYSB20160015)the Special Project for Inter-government Collaboration of the State Key Research and Development Program(Grant No.2016YFE0118400)the Jilin Provincial Science&Technology Department(Grant No.20180201026GX)the CAS Research and Development Project of Scientific Research Instruments and Equipmentthe Youth Innovation Promotion Association of CASsupported by the CAS Pioneer Hundred Talents Program
文摘The high density of defects induced by large strains in largely mismatched heteroepitaxy systems, such as AlN and GaN, because of the large lattice and thermal mismatch between substrates and epilayers is the bottleneck problem. Graphene-assisted van der Waals(vdW) heteroepitaxy offers a new opportunity to resolve this problem. However, it suffers from the difficulty of nucleation. Here we theoretically assess the effects of five 2D materials for vdW heteroepitaxy of AlN and GaN, including graphene, hBN, MoS2, gC3N, and gC3N4, and provide physical insights using first-principle calculations. MoS2 and gC3N exhibit significant potential to overcome the shortcomings of graphene owing to their appropriate binding strengths and Al(or Ga)diffusion barriers. Moreover, the interface behavior between the epilayers and the substrates are carefully analyzed. Our findings are helpful not only for obtaining high-quality AlN and GaN films but also for developing new criterions to discover effective 2D materials for vdW heteroepitaxy.
文摘This paper proposes a micro-LED backlight module with a distributed Bragg reflector(DBR) structure to achieve excellent micro-LED backlight module quality and uses deep reinforcement learning(DRL) architecture for optical design. In the DRL architecture, to solve the computing environment problems of the two extreme structures of micro-scale and macro-scale, this paper proposes an environment control agent and virtual-realistic workflow to ensure that the design environment parameters are highly correlated with experimental results. This paper successfully designed a micro-LED backlight module with a DBR structure by the abovementioned methods.The micro-LED backlight module with a DBR structure improves the uniformity performance by 32% compared with the micro-LED backlight module without DBR, and the design calculation time required by the DRL method is only 17.9% of the traditional optical simulation.
基金National Key Research and Development Plan(2017YFB0403000)National Science Fund for Distinguished Young Scholars(61725403)+6 种基金National Natural Science Foundation of China(61874118,61704171,61504083,61674161)CAS Pioneer Hundred Talents ProgramJilin Provincial Science&Technology Department(20180201026GX)Key Program of the International Partnership Program of CAS(181722KYSB20160015)Special Project for Inter-government Collaboration of the State Key Research and Development Program(2016YFE0118400)Youth Innovation Promotion Association of CASGuangdong Province Key Research and Development Plan(2019B010138002)。
文摘With the increasing demand for high integration and multi-color photodetection for both military and civilian applications, the research of multi-wavelength detectors has become a new research hotspot. However, current research has been mainly in visible dual-or multi-wavelength detectors, while integration of both visible light and ultraviolet(UV) dual-wavelength detectors has rarely been studied. In this work, large-scale and high-quality monolayer MoS2 was grown by the chemical vapor deposition method on transparent free-standing GaN substrate. Monolithic integration of MoS2-based visible detectors and GaN-based UV detectors was demonstrated using common semiconductor fabrication technologies such as photolithography, argon plasma etching, and metal deposition. High performance of a 280 nm and 405 nm dual-wavelength photodetector was realized.The responsivity of the UV detector reached 172.12 A/W, while that of the visible detector reached 17.5 A/W.Meanwhile, both photodetectors achieved high photocurrent gain, high external quantum efficiency, high normalized detection rate, and low noise equivalent power. Our study extends the future application of dual-wavelength detectors for image sensing and optical communication.
基金This work was supported by the National Key R&D Program of China,grant no.2017YFB1304400.
文摘Background:Deregulation of miRNA-21 expression has been reported to be associated with vascular smooth muscle behavior and cytoskeletal stability.This study is aimed to investigate the density of serum miRNA-21 in patients with different phases of intracranial aneurysms(IAs)and explore its warning function for IA rupture.Methods:A total of 16 in 200 IA patients were selected and categorized into 4 groups based on the phase of IA.Microarray study was carried out using serum miRNA and differentially expressed miRNAs were identified.Another 24 samples from a cohort of 360 patients were added and real-time polymerase chain reaction(RT-PCR)was performed on expanded sample size(n=40)for miRNA-21 validation.Potential gene targets of miRNA-21 were screened out from Gene Ontology(GO)database and literatures.Results:Microarray study identified 77 miRNAs with significantly different expression levels between experimental groups and the control group.RT-PCR assays validated significant downregulation of miRNA-21 in experimental groups,among which miRNA-21 expression level of daughter aneurysm group decreased the most.Bioinformatic analyses revealed that several target genes related with miRNA-21 may be involved in IA formation and rupture.Conclusions:This study suggested that miRNA-21 had a protective effect for intracranial vascular wall against remodeling and warning function for intracranial aneurysm rupture.Significant suppression of serum miRNA-21 in IA patients may provide diagnostic clues for aneurysm rupture and guide clinical intervention.
基金National Key Research and Development Program of China(2017YFB0403000)National Natural Science Foundation of China(61974144)+1 种基金Guangdong Province Key Research and Development Plan(2019B010138002)Key Research and Development Program of Guangdong Province(2020B010174003).
文摘Strain regulation as an effective way to enhance the photoelectric properties of two dimensional(2D)transition metal dichalcogenides has been widely employed to improve the performance of photovoltaic devices.In this work,tensile strain was introduced in multilayer MoS2 grown on GaN by depositing 3 nm of Al2O3 on the surface.The temperature dependent Raman spectrum shows that the thermal stability of MoS2 is improved by Al2O3.Theoretical simulations confirmed the existence of tensile strain on MoS2 covered with Al2O3,and the bandgap and electron effective mass of six layers of MoS2 decreased due to tensile strain,which resulted in an increase of electron mobility.Due to the tensile strain ffect,the photodetector with the Al2O3 stress liner achieved better performance under the illumination of 365 nm wavelength,including a higher responsivity of 24.6 A/W,photoconductive gain of 520,and external quantum fficiency of 8381%,which are more than twice the corresponding values of photodetectors without Al2O3.Our work provides an effective technical way for improving the performance of 2D material photodetectors.
