Trap levels analysis in MWIR InAs/InAsSb T2SL photodiode

Mid-wave infrared (MWIR) photodiode with an InAs/InAsSb superlattice active layer was characterized by the photoluminescence (PL), spectral response (SR) and deep level transient spectroscopy (DLTS) measurements. Three independent methods, in combination with the theoretical calculations, were used to determine the transitions between superlattice minibands, as well as to and from the trap states. The determined effective band gap of the investigated superlattice is 251 meV at 70 K. Most of the detected trap states lie within the energy gap, around 60 and 80 meV below the first electron miniband, and near the mid-gap. Moreover, trap states located above the first electron miniband and below the first light hole miniband were also observed. It is worth emphasizing that the PL and DLTS measurements give consistent results. Additionally, the activation energy of 16 meV for the Be acceptor dopant was determined using the PL measurement.