Very long wavelength type-II InAs/GaSb superlattice infrared detectors

In this paper, results from the development of LWIR and VLWIR InAs/GaSb type-II infrared photodetector arrays are presented. Dark currents comparable to the HgCdTe benchmark (Rule07) have been observed and the quantum efficiencies of the detectors exceed 30 %. Bias and temperature dependencies of the QE have been studied showing very low turn on bias (similar to-25mV) and no variation of the peak QE value with temperature. These results show that there are no unintentional barriers in the detector structures and that the diffusion lengths are long enough to provide efficient collection of carriers. Initial results from the extension of the cut-off wavelength from 11 mu m to 14 mu m are also presented as well as initial results from photodiodes with thicker absorbers to enhance the QE.