Binary superlattice quantum-well infrared photodetectors for long-wavelength broadband detection

Abstract

We have adopted a binary superlattice structure for long-wavelength broadband detection. In this superlattice, the basis contains two unequal wells, with which more energy states are created for broadband absorption. At the same time, responsivity is more uniform within the detection band because of mixing of wave functions from the two wells. This uniform line shape is particularly suitable for spectroscopy applications. The detector is designed to cover the entire 8–14μm long-wavelength atmospheric window. The observed spectral widths are 5.2 and 5.6μm for two nominally identical wafers. The photoresponse spectra from both wafers are nearly unchanged over a wide range of operating bias and temperature. The background-limited temperature is 50K at 2V bias for F∕1.2 optics.