The in-plane optical anisotropy(IPOA) of c-plane In Ga N/Ga N quantum disks(Qdisks) in nanowires grown on MoS_(2)/Mo and Ti/Mo substrates is investigated using reflectance difference spectroscopy(RDS) at room temperat...The in-plane optical anisotropy(IPOA) of c-plane In Ga N/Ga N quantum disks(Qdisks) in nanowires grown on MoS_(2)/Mo and Ti/Mo substrates is investigated using reflectance difference spectroscopy(RDS) at room temperature. A large IPOA related to defect or impurity states is observed. The IPOA of samples grown on MoS_(2)/Mo is approximately one order of magnitude larger than that of samples grown on Ti/Mo substrates. Numerical calculations based on the envelope function approximation have been performed to analyze the origin of the IPOA. It is found that the IPOA primarily results from the segregation of indium atoms in the In Ga N/Ga N Qdisks. This work highlights the significant influence of substrate materials on the IPOA of semiconductor heterostructures.展开更多
The InGaN films and GaN/InGaN/GaN tunnel junctions(TJs)were grown on GaN templates with plasma-assisted molecular beam epitaxy.As the In content increases,the quality of InGaN films grown on GaN templates decreases an...The InGaN films and GaN/InGaN/GaN tunnel junctions(TJs)were grown on GaN templates with plasma-assisted molecular beam epitaxy.As the In content increases,the quality of InGaN films grown on GaN templates decreases and the surface roughness of the samples increases.V-pits and trench defects were not found in the AFM images.p++-GaN/InGaN/n++-GaN TJs were investigated for various In content,InGaN thicknesses and doping concentration in the InGaN insert layer.The InGaN insert layer can promote good interband tunneling in GaN/InGaN/GaN TJ and significantly reduce operating voltage when doping is sufficiently high.The current density increases with increasing In content for the 3 nm InGaN insert layer,which is achieved by reducing the depletion zone width and the height of the potential barrier.At a forward current density of 500 A/cm^(2),the measured voltage was 4.31 V and the differential resistance was measured to be 3.75×10^(−3)Ω·cm^(2)for the device with a 3 nm p++-In_(0.35)Ga_(0.65)N insert layer.When the thickness of the In_(0.35)Ga_(0.65)N layer is closer to the“balanced”thickness,the TJ current density is higher.If the thickness is too high or too low,the width of the depletion zone will increase and the current density will decrease.The undoped InGaN layer has a better performance than n-type doping in the TJ.Polarization-engineered tunnel junctions can enhance the functionality and performance of electronic and optoelectronic devices.展开更多
Force sensing provides a crucial physical-electrical channel within sensing technology.This study showcases the fabrication and characterization of force sensors by integrating a polydimethylsiloxane(PDMS)mechanical m...Force sensing provides a crucial physical-electrical channel within sensing technology.This study showcases the fabrication and characterization of force sensors by integrating a polydimethylsiloxane(PDMS)mechanical module and an optical channel formed by two ideal InGaN/GaN light-emitting diodes(LEDs)with transmit-receive characteristics.As an emitter,the InGaN/GaN device(5 mm×4 mm)exhibits electroluminescence at 469 nm with an on-voltage of 2.33 V.As a receiver,the response spectrum of InGaN/GaN devices spans from 350 to 480 nm,featuring a peak at 390 nm,rise time of~68.4 ms,and falling edge of~61.0 ms.The PDMS film can transform the force into deformation data and influence the signals in the optical receiver.The drive current,the gap between the emitter and receiver,and distance between the LED and PDMS mechanical module all significantly influence the receiver photocurrent.Distinct from the integrated design,our PDMS-assisted force sensing model uses discrete structures to allow signal intensity optimization.The finite element simulation and experimental results indicate that force of the designed PDMS film exhibits a linear relationship with z-axis displacement and photocurrent from 0 to 0.7 mm.The findings reveal that when the PDMS film height is 1.5 mm and the distance between the emitter and receiver is near,the photocurrent is higher.Meanwhile,Ag film with a thickness of 100 nm considerably enhances the photocurrent response and signal stability in the sensing channel.Finally,a weight measurement demonstration is employed to demonstrate force sensing.The system resolution is 1.23μA/N,and the measurement range is 0 to 0.7 N.展开更多
利用 LP- MOCVD技术在 Ga As( 0 0 1 )衬底上生长了高质量的立方相 In Ga N外延层 .研究了生长速率对 In Ga N质量的影响 ,提出一个简单模型解释了在改变 TEGa流量条件下出现的In组分的变化规律 ,实验结果与模型的一次项拟合结果较为吻...利用 LP- MOCVD技术在 Ga As( 0 0 1 )衬底上生长了高质量的立方相 In Ga N外延层 .研究了生长速率对 In Ga N质量的影响 ,提出一个简单模型解释了在改变 TEGa流量条件下出现的In组分的变化规律 ,实验结果与模型的一次项拟合结果较为吻合 ,由此推断 ,在现在的生长条件下 ,表面单个 Ga原子作为临界晶核吸附 Ga或 In原子实现生长的模型与实际情况较为接近 .对于晶体质量的变化也给予了说明 .得到的高质量立方相 In Ga N室温下有很强的发光峰 ,光致发光峰半高宽为 1 2 8me V左右 .展开更多
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 62074036, 61674038, and 11574302)Foreign Cooperation Project of Fujian Province (Grant No. 2023I0005)+2 种基金Open Research Fund Program of the State Key Laboratory of Low-Dimensional Quantum Physics (Grant No. KF202108)the National Key Research and Development Program (Grant No. 2016YFB0402303)the Foundation of Fujian Provincial Department of Industry and Information Technology of China (Grant No. 82318075)。
文摘The in-plane optical anisotropy(IPOA) of c-plane In Ga N/Ga N quantum disks(Qdisks) in nanowires grown on MoS_(2)/Mo and Ti/Mo substrates is investigated using reflectance difference spectroscopy(RDS) at room temperature. A large IPOA related to defect or impurity states is observed. The IPOA of samples grown on MoS_(2)/Mo is approximately one order of magnitude larger than that of samples grown on Ti/Mo substrates. Numerical calculations based on the envelope function approximation have been performed to analyze the origin of the IPOA. It is found that the IPOA primarily results from the segregation of indium atoms in the In Ga N/Ga N Qdisks. This work highlights the significant influence of substrate materials on the IPOA of semiconductor heterostructures.
基金National Natural Science Foundation of China(No.62204127)the Natural Science Foundation of Jiangsu Province(No.BK20215093)State Key Laboratory of Luminescence and Applications(No.SKLA‒2021‒04)。
基金supported by the National Key Research and Development Program of China (2017YFE0131500, 2022YFB2802801)the National Natural Science Foundation of China (61834008, U21A20493)+1 种基金the Key Research and Development Program of Jiangsu Province (BE2020004, BE2021008-1)the Suzhou Key Laboratory of New-type Laser Display Technology (SZS2022007)
文摘The InGaN films and GaN/InGaN/GaN tunnel junctions(TJs)were grown on GaN templates with plasma-assisted molecular beam epitaxy.As the In content increases,the quality of InGaN films grown on GaN templates decreases and the surface roughness of the samples increases.V-pits and trench defects were not found in the AFM images.p++-GaN/InGaN/n++-GaN TJs were investigated for various In content,InGaN thicknesses and doping concentration in the InGaN insert layer.The InGaN insert layer can promote good interband tunneling in GaN/InGaN/GaN TJ and significantly reduce operating voltage when doping is sufficiently high.The current density increases with increasing In content for the 3 nm InGaN insert layer,which is achieved by reducing the depletion zone width and the height of the potential barrier.At a forward current density of 500 A/cm^(2),the measured voltage was 4.31 V and the differential resistance was measured to be 3.75×10^(−3)Ω·cm^(2)for the device with a 3 nm p++-In_(0.35)Ga_(0.65)N insert layer.When the thickness of the In_(0.35)Ga_(0.65)N layer is closer to the“balanced”thickness,the TJ current density is higher.If the thickness is too high or too low,the width of the depletion zone will increase and the current density will decrease.The undoped InGaN layer has a better performance than n-type doping in the TJ.Polarization-engineered tunnel junctions can enhance the functionality and performance of electronic and optoelectronic devices.
基金supported by the Natural Science Foundation of Jiangsu Province(BK20210593)the National Natural Science Foundation of China(62204127,62404040)the Fundamental Research Funds for the Central Universities(No.NS2022096).
文摘Force sensing provides a crucial physical-electrical channel within sensing technology.This study showcases the fabrication and characterization of force sensors by integrating a polydimethylsiloxane(PDMS)mechanical module and an optical channel formed by two ideal InGaN/GaN light-emitting diodes(LEDs)with transmit-receive characteristics.As an emitter,the InGaN/GaN device(5 mm×4 mm)exhibits electroluminescence at 469 nm with an on-voltage of 2.33 V.As a receiver,the response spectrum of InGaN/GaN devices spans from 350 to 480 nm,featuring a peak at 390 nm,rise time of~68.4 ms,and falling edge of~61.0 ms.The PDMS film can transform the force into deformation data and influence the signals in the optical receiver.The drive current,the gap between the emitter and receiver,and distance between the LED and PDMS mechanical module all significantly influence the receiver photocurrent.Distinct from the integrated design,our PDMS-assisted force sensing model uses discrete structures to allow signal intensity optimization.The finite element simulation and experimental results indicate that force of the designed PDMS film exhibits a linear relationship with z-axis displacement and photocurrent from 0 to 0.7 mm.The findings reveal that when the PDMS film height is 1.5 mm and the distance between the emitter and receiver is near,the photocurrent is higher.Meanwhile,Ag film with a thickness of 100 nm considerably enhances the photocurrent response and signal stability in the sensing channel.Finally,a weight measurement demonstration is employed to demonstrate force sensing.The system resolution is 1.23μA/N,and the measurement range is 0 to 0.7 N.
