Mid-infrared optical absorption in InAs/AlSb/GaSb based quantum well system

Abstract The dependence of the optical absorption coefficient on the width of the AlSb caplayer is investigated in InAs/AlSb/GaSb based quantum well system (QWs). The optical absorption coefficient is calculated by employing the balance equation method to solve the Boltzmann equation. Two peaks in the optical absorption coefficient are observed due to the intraband transitions. The AlSb caplayer is inserted between the InAs layer and the GaSb layer to reduce the generation–recombination (g–r) noise induced by the interband transitions. The optical absorption coefficients induced by the interband transitions are significantly reduced when the width of the AlSb caplayer reaches up to 2 nm . The optical absorption peaks lie in the mid-infrared region and decrease slightly with the increase of the temperature even up to room temperature. Our theoretical results suggest that the InAs/AlSb/GaSb based QWs can be used as room temperature mid-infrared detectors with low noise.