NORMAL INCIDENCE INFRARED PHOTOABSORPTION IN P-TYPE GASB/GAXAL1-XSB QUANTUM-WELLS

Absorption of infrared radiation at normal incidence from intervalence-subband transitions is investigated in p-type GaSb/Ga1-xAlxSb quantum wells. Normal incidence absorption is allowed in conventional p-type quantum wells due to the favorable properties of the p-like valence-band Bloch states and the heavy- and light-hole mixing. By using GaSb as the quantum-well material, which has the smallest heavy-hole effective mass of the commonly used III-V semiconductors, absorption can be further enhanced. We find that normal incidence absorption of 3000-6000 cm-1 can be easily achieved in these proposed quantum wells with well widths of 55-90 angstrom for the wavelength range of 8-12-mu-m and typical sheet doping concentrations of 10(12) cm-2. This absorption strength is comparable to that in the intrinsic Hg1-xCdxTe detector. Strong absorption of normally incident radiation makes this structure a good candidate for infrared photodetection.