A SPECTROSCOPIC STUDY OF GAAS HOMOJUNCTION INTERNAL PHOTOEMISSION FAR-INFRARED DETECTORS

We report a spectroscopic study of absorption and photoconductivity in GaAs homojunction interfacial workfunction internal photoemission (HI WIP) far-infrared (FIR) detectors utilizing molecular beam epitaxy (MB E) grown multilayer (p(+)-p(-)-p(+)-p(-)...) structures. Strong FIR (5 0-200 mu m) free carrier absorption has been observed and analyzed for a p(+) GaAs thin film, revealing the suitability for FIR detection. T he basic physical mechanism of free carrier absorption in the HIWIP FI R detectors has been determined to be an acoustic phonon-emission assi sted process, A simple recombination model is proposed to account for the bias dependence of the responsivity and the saturation behavior, U sing the measured responsivity and dark current data, detectivity (D-l ambda) of the FIR detectors has also been estimated. (C) 1997 Elsevie r Science B.V.