Investigation of Quantum Well Infrared Photodetetors on (311)A GaAs and In0.52Al0.48As/InAs/InxAl1-xAs Pseudomorphic HEMT on InP

• Main Authors: Liao, C. C., 廖金昌
• Other Authors: Hsieh, I. J.
• Format: Others
• Language: en_US
• Published: 1997
• Online Access: http://ndltd.ncl.edu.tw/handle/22835325982873516878

碩士 === 中華大學 === 電機工程研究所 === 85 === We have studied two Si-doped p-type quantum well infrared photodetectors (QWIPs) using AlGaAs/GaAs and AlGaAs/InGaAs grown on (311)A GaAs and In0.52Al0.48As/InAs/InxAl1-xAs Pseudomorphic HEMT on InP. The Si-doped AlGaAs/GaAs p-QWIP exhibits a symmetrical dark I-V characteristic at all the measured temperatures from 40K to 120K. The strained p-type AlGaAs/InGaAs QWIP exhibits a slightly asymmetrical dark I-V characteristic, but is markedly less asymmetrical than that doped with beryllium. The slight asymmetry in dark I-V characteristic and the large blue-shift in responsivity spectra may be due to the thickness modulation observed from TEM and the red-shift of PL peak energy, where PL peak energies from (311)A AlGaAs/InGaAs multiple quantum wells are red-shifts of 7 and 22 meV to the side-by-side grown (100). The dc and microwave performance of a InAs channel HEMT is reported. Room-temperature electron mobility as high as 20,200 cm2/V-s is measured, with a high carrier concentration of 2.7x1012cm-2.DC extrinsic transconductance of 714mS/mm is measured and a unity-current-gain cut-off frequency of 50GHz is obtained for a 1.1mm gate length HEMT. The success of achieving superior Hall mobility and device performance is strongly dependent on the InxAl1-xAs buffer layer design that changes the lattice constant from lattice-matched In0.52Al0.48As to In0.75Al0.25As. The multiple In0.52Al0.48As/InAs monolayer superlattices buffer achieves the best performance as compared to the step-graded InxAl1-xAs and the uniform In0.75Al0.25As buffer.