<title>InAs/InGaSb superlattices for very long wavelength infrared detection</title>

Abstract

New infrared detector materials with high sensitivity, multi-spectral capability, improved uniformity and lower manufacturing costs are required for numerous long and very long wavelength infrared imaging applications. One materials system has shown great theoretical and, more recently, experimental promise for these applications: InAs/In x Ga 1-x Sb type-II superlattices. In the past few years, excellent results have been obtained on photoconductive and photodiode samples designed for infrared detection beyond 10 microns. Far-infrared photoresponse of superlattices with cut-off wavelengths between 15 µm and 25 µm were studied. The measured photoresponse spectra for both photodiodes and photoconductors are compared to calculated absorption coefficient spectra. The electronic structure and the optical absorption of InAs/ In x Ga 1-x Sb superlattice infrared (IR) detector structures are calculated, for several values of x, using our implementation of the 8x8 envelope-function approximation (EFA) formalism. Good experimental-theoretical agreement is obtained regarding the long-wavelength threshold and absorption shape.

Progress in Infrared Photodetectors Since 2000

“…There have also been studies concluding higher values for the effective electron mass in these devices, which can also lead to reduced Auger recombination rates [133,140–142]. SLS devices also tend to be more tolerant to growth variances than MCT, particularly in terms of mole fraction composition [143]. …”

“…Performance of InAs/InGaSb devices was usually similar to devices utilizing InAs/GaSb structures. However, GaSb was usually the preferred due to more convenient material growth [143,170–172]. …”