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
Ag纳米粒子的形貌对InGaN/Ga N多量子阱(MQWs)的光致发光(PL)效率有着显著影响。本文采用离子束沉积(IBD)技术将Ag沉积在InGaN/Ga N MQWs上,然后通过快速热退火处理制备Ag纳米粒子。通过改变Ag的沉积时间获得了具有不同Ag纳米粒子形貌...Ag纳米粒子的形貌对InGaN/Ga N多量子阱(MQWs)的光致发光(PL)效率有着显著影响。本文采用离子束沉积(IBD)技术将Ag沉积在InGaN/Ga N MQWs上,然后通过快速热退火处理制备Ag纳米粒子。通过改变Ag的沉积时间获得了具有不同Ag纳米粒子形貌的样品。用原子力显微镜对各样品的Ag纳米粒子形貌和尺寸进行了表征,并且测试了吸收谱、室温和变温PL谱及时间分辨光致发光(TRPL)谱。结果表明:随着Ag沉积时间的延长,所得Ag纳米粒子粒径增大,粒子纵横比先增大后减小且吸收谱峰红移。由于不同形貌的Ag纳米粒子在入射光作用下产生的局域表面等离激元(LSPs)与MQWs中激子耦合强度不同,光发射能力也不同,与没有Ag纳米粒子的样品相比,沉积时间为15 s的样品室温PL积分强度被抑制6.74倍,沉积时间为25 s和35 s的样品室温PL积分强度分别增强1.55和1.72倍且峰位发生红移,沉积时间为45 s的样品室温PL积分强度基本没有变化。TRPL与变温PL的测试结果证明,室温PL积分强度的改变是由于LSPs与MQWs中的激子耦合作用引起的。纵横比大且吸收谱与MQWs的PL谱交叠大的Ag纳米粒子能够更好地增强InGaN/Ga N MQWs的发光。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.
文摘Ag纳米粒子的形貌对InGaN/Ga N多量子阱(MQWs)的光致发光(PL)效率有着显著影响。本文采用离子束沉积(IBD)技术将Ag沉积在InGaN/Ga N MQWs上,然后通过快速热退火处理制备Ag纳米粒子。通过改变Ag的沉积时间获得了具有不同Ag纳米粒子形貌的样品。用原子力显微镜对各样品的Ag纳米粒子形貌和尺寸进行了表征,并且测试了吸收谱、室温和变温PL谱及时间分辨光致发光(TRPL)谱。结果表明:随着Ag沉积时间的延长,所得Ag纳米粒子粒径增大,粒子纵横比先增大后减小且吸收谱峰红移。由于不同形貌的Ag纳米粒子在入射光作用下产生的局域表面等离激元(LSPs)与MQWs中激子耦合强度不同,光发射能力也不同,与没有Ag纳米粒子的样品相比,沉积时间为15 s的样品室温PL积分强度被抑制6.74倍,沉积时间为25 s和35 s的样品室温PL积分强度分别增强1.55和1.72倍且峰位发生红移,沉积时间为45 s的样品室温PL积分强度基本没有变化。TRPL与变温PL的测试结果证明,室温PL积分强度的改变是由于LSPs与MQWs中的激子耦合作用引起的。纵横比大且吸收谱与MQWs的PL谱交叠大的Ag纳米粒子能够更好地增强InGaN/Ga N MQWs的发光。
