Direct-current transfer characteristics of （InGaN）/A1GaN/A1N/GaN heterojunction field effect transistors （HFETs） are presented. A drain current plateau （IDs = 32.0 mA/mm） for Vcs swept from ＋0.7 V to -0. 6 V is...Direct-current transfer characteristics of （InGaN）/A1GaN/A1N/GaN heterojunction field effect transistors （HFETs） are presented. A drain current plateau （IDs = 32.0 mA/mm） for Vcs swept from ＋0.7 V to -0. 6 V is present in the transfer characteristics of InGaN/AIGaN/AIN/GaN HFETs. The theoretical calculation shows the coexistence of two-dimensional electron gas （2DEG） and two-dimensional hole gas （2DHG） in InGaN/AIGaN/A1N/GaN heterostructures, and the screening effect of 2DHG to the 2DEG in the conduction channel can explain this current plateau. Moreover, the current plateau shows the time-dependent behavior when IDs Vcs scans repeated are conducted. The obtained insight provides indication for the design in the fabrication of GaN-based super HFETs.展开更多
Electrical and optical properties of InGaN/AlGaN double heterostructure blue light-emitting diodes were investigated.Measurement of the forward bias current-voltage behaviour of the device demonstrated a departure fro...Electrical and optical properties of InGaN/AlGaN double heterostructure blue light-emitting diodes were investigated.Measurement of the forward bias current-voltage behaviour of the device demonstrated a departure from the Shockley model of a p-n diode,and it was observed that the dominant mechanism of carrier transport across the junction is associated with carrier tunnelling.Electroluminescence experiments indicated that there was a main emission band around 2.80 eV and a relatively weaker peak at 3.2 eV.A significant blueshift of the optical emission band was observed,which was consistent with the tunnelling character of electrical characteristics.Furthermore,the degradation in I-V characteristics and the low resistance ohmic short of the device were observed.展开更多
Owing to the low p-type doping efficiency in the hole injection layers(HILs)of GaN-based ultra-violet(UV)vertical-cavity surface-emitting laser(VCSEL),effective hole injection in multi-quantum wells(MQW)is not achieve...Owing to the low p-type doping efficiency in the hole injection layers(HILs)of GaN-based ultra-violet(UV)vertical-cavity surface-emitting laser(VCSEL),effective hole injection in multi-quantum wells(MQW)is not achieved,significantly limiting the photoelectric performance of UV VCSELs.We developed a slope-shaped HIL and an EBL structure in AlGaN-based UV VCSELs.In this study,by improving hole in-jection efficiency,the hole concentration in the HIL is increased,and the hole barrier at the electron barrier layer(EBL)/HIL interface is decreased.This minimises the hindering effect of hole injection.A mathematic-al model of this structure was established using a commercial software,photonic integrated circuit simulator in three-dimension(PICS3D).We conducted simulations and theoretical analyses of the band structure and carrier concentration.Introducing polarisation doping through the Al composition gradient in the HIL en-hanced the hole concentration,thereby improving the hole injection efficiency.Furthermore,modifying the EBL eliminated the abrupt potential barrier for holes at the HIL/EBL interface,smoothing the valence band.This improved the stimulated radiative recombination rate in the MQW,increasing the laser power.There-fore,the sloped p-type layer can enhance the optoelectronic performance of UV VCSELs.展开更多
基金Supported by the Knowledge Innovation Project of the Chinese Academy of Sciencesthe National Natural Science Foundation of China under Grant Nos 61204017 and 61334002+1 种基金the National Basic Research Program of Chinathe National Science and Technology Major Project of China
文摘Direct-current transfer characteristics of （InGaN）/A1GaN/A1N/GaN heterojunction field effect transistors （HFETs） are presented. A drain current plateau （IDs = 32.0 mA/mm） for Vcs swept from ＋0.7 V to -0. 6 V is present in the transfer characteristics of InGaN/AIGaN/AIN/GaN HFETs. The theoretical calculation shows the coexistence of two-dimensional electron gas （2DEG） and two-dimensional hole gas （2DHG） in InGaN/AIGaN/A1N/GaN heterostructures, and the screening effect of 2DHG to the 2DEG in the conduction channel can explain this current plateau. Moreover, the current plateau shows the time-dependent behavior when IDs Vcs scans repeated are conducted. The obtained insight provides indication for the design in the fabrication of GaN-based super HFETs.
基金国家自然科学基金(批准号:60676032,60276010,60376025,60276034)和北京市科技计划(批准号:H030430020230)资助项目 Project supported by the National Natural Science Foundation of China(Nos. 60676032,60276010,60376025,60276034) and the Beijing Scientific & Technical Program(No.H030130020230)
基金Supported by the National Natural Science Foundation of China under Grant Nos.69806006,69636010,69976017 and 69987001the National High Technology Research&Development Project of China(No.863-715-011-0030).
文摘Electrical and optical properties of InGaN/AlGaN double heterostructure blue light-emitting diodes were investigated.Measurement of the forward bias current-voltage behaviour of the device demonstrated a departure from the Shockley model of a p-n diode,and it was observed that the dominant mechanism of carrier transport across the junction is associated with carrier tunnelling.Electroluminescence experiments indicated that there was a main emission band around 2.80 eV and a relatively weaker peak at 3.2 eV.A significant blueshift of the optical emission band was observed,which was consistent with the tunnelling character of electrical characteristics.Furthermore,the degradation in I-V characteristics and the low resistance ohmic short of the device were observed.
文摘Owing to the low p-type doping efficiency in the hole injection layers(HILs)of GaN-based ultra-violet(UV)vertical-cavity surface-emitting laser(VCSEL),effective hole injection in multi-quantum wells(MQW)is not achieved,significantly limiting the photoelectric performance of UV VCSELs.We developed a slope-shaped HIL and an EBL structure in AlGaN-based UV VCSELs.In this study,by improving hole in-jection efficiency,the hole concentration in the HIL is increased,and the hole barrier at the electron barrier layer(EBL)/HIL interface is decreased.This minimises the hindering effect of hole injection.A mathematic-al model of this structure was established using a commercial software,photonic integrated circuit simulator in three-dimension(PICS3D).We conducted simulations and theoretical analyses of the band structure and carrier concentration.Introducing polarisation doping through the Al composition gradient in the HIL en-hanced the hole concentration,thereby improving the hole injection efficiency.Furthermore,modifying the EBL eliminated the abrupt potential barrier for holes at the HIL/EBL interface,smoothing the valence band.This improved the stimulated radiative recombination rate in the MQW,increasing the laser power.There-fore,the sloped p-type layer can enhance the optoelectronic performance of UV VCSELs.
