AlGaN/GaN high electron mobility transistors （HEMTs） grown on Fe-modulation-doped （MD） and unintentionally doped （UID） GaN buffer layers are investigated and compared. Highly resistive GaN buffers （10^9Ω·...AlGaN/GaN high electron mobility transistors （HEMTs） grown on Fe-modulation-doped （MD） and unintentionally doped （UID） GaN buffer layers are investigated and compared. Highly resistive GaN buffers （10^9Ω·cm） are induced by individual mechanisms for the electron traps＇ formation： the Fe MD buffer （sample A） and the UID buffer with high density of edge-type dislocations （7.24×10^9cm^-2, sample B）. The 300K Hall test indicates that the mobility of sample A with Fe doping （2503cm^2V^-1s^-1） is much higher than sample B （1926cm^2V^-1s^-1） due to the decreased scattering effect on the two-dimensional electron gas. HEMT devices are fabricated on the two samples and pulsed I–V measurements are conducted. Device A shows better gate pinch-off characteristics and a higher threshold voltage （-2.63V） compared with device B （-3.71V）. Lower gate leakage current ｜IGS｜ of device A （3.32×10^-7A） is present compared with that of device B （8.29×10^-7A）. When the off-state quiescent points Q_2 （V GQ2=-8V, V DQ2=0V） are on, V th hardly shifts for device A while device B shows ＋0.21V positive threshold voltage shift, resulting from the existence of electron traps associated with the dislocations in the UID-GaN buffer layer under the gate. Under pulsed I–V and transconductance G m–V GS measurement, the device with the Fe MD-doped buffer shows more potential in improving reliability upon off-state stress.展开更多
Modulation-doped AlGaAs/GaAs structures were grown on GaAs(100) substrate by solid source molecular beam epitaxy(SSMBE) system. The factors which influence the electron mobility were investigated. After growing InP ba...Modulation-doped AlGaAs/GaAs structures were grown on GaAs(100) substrate by solid source molecular beam epitaxy(SSMBE) system. The factors which influence the electron mobility were investigated. After growing InP based materials, growth conditions were deteriorated, but by an appropriate method and using reasonable process high electron mobility(77 K) of more than 1.50×10~5 cm^2/(V·s) can still be obtained. The structures and growth conditions have been studied and optimized via Hall measurements. For a typical sample, 2.0 K electron mobility as high as 1.78×10~6 cm^2/(V·s) is achieved, and the quantum Hall oscillation phenomena can be observed.展开更多
基金Supported by the National Natural Science Foundation of China under Grant Nos 61204017 and 61334002the National Basic Research Program of Chinathe National Science and Technology Major Project of China
文摘AlGaN/GaN high electron mobility transistors （HEMTs） grown on Fe-modulation-doped （MD） and unintentionally doped （UID） GaN buffer layers are investigated and compared. Highly resistive GaN buffers （10^9Ω·cm） are induced by individual mechanisms for the electron traps＇ formation： the Fe MD buffer （sample A） and the UID buffer with high density of edge-type dislocations （7.24×10^9cm^-2, sample B）. The 300K Hall test indicates that the mobility of sample A with Fe doping （2503cm^2V^-1s^-1） is much higher than sample B （1926cm^2V^-1s^-1） due to the decreased scattering effect on the two-dimensional electron gas. HEMT devices are fabricated on the two samples and pulsed I–V measurements are conducted. Device A shows better gate pinch-off characteristics and a higher threshold voltage （-2.63V） compared with device B （-3.71V）. Lower gate leakage current ｜IGS｜ of device A （3.32×10^-7A） is present compared with that of device B （8.29×10^-7A）. When the off-state quiescent points Q_2 （V GQ2=-8V, V DQ2=0V） are on, V th hardly shifts for device A while device B shows ＋0.21V positive threshold voltage shift, resulting from the existence of electron traps associated with the dislocations in the UID-GaN buffer layer under the gate. Under pulsed I–V and transconductance G m–V GS measurement, the device with the Fe MD-doped buffer shows more potential in improving reliability upon off-state stress.
文摘Modulation-doped AlGaAs/GaAs structures were grown on GaAs(100) substrate by solid source molecular beam epitaxy(SSMBE) system. The factors which influence the electron mobility were investigated. After growing InP based materials, growth conditions were deteriorated, but by an appropriate method and using reasonable process high electron mobility(77 K) of more than 1.50×10~5 cm^2/(V·s) can still be obtained. The structures and growth conditions have been studied and optimized via Hall measurements. For a typical sample, 2.0 K electron mobility as high as 1.78×10~6 cm^2/(V·s) is achieved, and the quantum Hall oscillation phenomena can be observed.
