Normal incidence intervalence subband absorption in GaSb quantum well enhanced by coupling to InAs conduction band

We demonstrate a novel infrared (IR) detector structure based on the type II p-doped InAs/GaSb multiquantum well system. Due to the coupling of the first conduction subband in InAs to the valence band states in GaSb, the normal incidence absorption coefficient for intervalence subband transitions between heavy and light hole subbands in GaSb quantum wells is significantly enhanced. An absorption coefficient as large as 6500 cm−1 has been achieved in the wavelength range of 8–17 μm. This is the strongest absorption ever observed among all the IR materials in this wavelength range.