In this communication, we report on electrical and electro-optical characterizations of InAs/GaSb Type-II superlattice (T2SL) LWIR photodetector, showing cut-off wavelengths at 11μm at 77K. The devices, made of barrier structures in XBp configuration, were grown by molecular beam epitaxy (MBE) on GaSb substrate. Experimental measurements on samples were made by photoresponse spectra, by capacitance-voltage (C-V) and dark current-voltage (I-V) characteristics performed as a function of temperature.
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 (~-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 μm to 14 μm are also presented as well as initial results from photodiodes with thicker absorbers to enhance the QE.
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