A spectroscopic study of GaAs homojunction internal photoemission far infrared detectors

Abstract

We report a spectroscopic study of absorption and photoconductivity in GaAs homojunction interfacial workfunction internal photoemission (HIWIP) far-infrared (FIR) detectors utilizing molecular beam epitaxy (MBE) grown multilayer (p+−p−−p+−p−) structures. Strong FIR (50–200 μm) free carrier absorption has been observed and analyzed for a p+ GaAs thin film, revealing the suitability for FIR detection. The basic physical mechanism of free carrier absorption in the HIWIP FIR detectors has been determined to be an acoustic phonon-emission assisted process. A simple recombination model is proposed to account for the bias dependence of the responsivity and the saturation behavior. Using the measured responsivity and dark current data, detectivity (Dλ∗) of the FIR detectors has also been estimated.