InGaAs/GaAsSb Type-II Superlattice for infrared imaging towards 2.5μm.

In the frame of the European SWIRup project, this work deals with the research of new materials for the detection of the upper band of Short Wavelength InfraRed (SWIR) radiation up to 2.5μm at high working temperature. The current technology, consisting of HgCdTe, shows some limitations and it requires cryogenic temperatures to work. As an alternative, InGaAs/GaAsSb Type-II SuperLattice (T2SL) is analysed through kp simulations. From experimental Quantum Efficiency (QE) measurements on some test devices, the problem of carrier localization appears as an exponential dependence on temperature of the QE at a given wavelength. By means of the simulations, the structure is optimized by following a quite simple model based on the scattering time. In particular, strain in the superlattice layers is adopted to achieve the lowest effective mass at the highest cutoff wavelength.