Normal incidence infrared photoabsorption in p-type GaSb/GaxAl1−xSb quantum wells

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Abstract
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 Å for the wavelength range of 8–12 μm and typical sheet doping concentrations of 1012 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.