Trap parameters in the infrared InAsSb absorber found by capacitance and noise measurements

We reported experimentally determined trap parameters for the narrow-gap InAs1-xSbx material with the ternary composition x = 0.18. The deep level transient spectroscopy supported by the low frequency noise spectroscopy were used to study traps in the mid-wavelength infrared (IR) photodetector with the InAs1-xSbx absorber. The trap levels within the bandgap, theirs capture cross-sections and trap concentration were found. Experimentally obtained parameters are consistent with calculated values reported in the literature. The trap levels E-t = 140-145 meV and E-t = 45 meV, with respect to the valence band edge, are the most important for IR detectors because levels seem to be pinned to the valence band edge. It means that they are insensitive to composition x of the InAs1-xSbx alloy. Consequently, for bulk detectors, each level can lie around the middle of the bandgap and can become an efficient generation-recombination center which degrades the minority carrier lifetime in the mid-wavelength (trap level 140-145 meV) or long-wavelength (trap level 45 meV) IR devices based on the InAs1-xSbx material. The levels can be also important for the emerging IR material, i.e. superlattice InAs/InAs1-xSbx, where the midgap states can be also introduced by traps located in the InAs1-xSbx ternary alloy.