Doping effects on intersubband and interband optical transitions in GaSb-InAs superlattices

Normal incidence intersubband and interband absorptions of a novel type II GaSb-InAs superlattices can be obtained by utilizing the various doped-type cap and buffer layers. Moreover, the types and intensities of the absorptions could also be modulated by changing doping concentration. The intersubband transition can occur due to the strong mixing of the heavy-hole band and the light-hole band for InAs n-type cap and buffer layers. But the interband transition is a result of coupling between the wave-functions of the first conduction subband and the first heavy-hole subband for GaSb p-type cap and buffer layers. Both the intensities of intersubband can be modulated by changing doping concentration, and the corresponding wavelengths are in the ranges of 3-5 μm and 8-14 μm, respectively. Hence, it shows the potential application as an infrared photodetector