Infrared Transmission and Fluorescence of Doped Gallium Arsenide

Abstract

Experimental measurements of the fundamental optical absorption edge show that with increased doping, $n$-type GaAs exhibits a shift of the optical absorption edge to higher energy at 77°K, while $p$-type GaAs at 300°K shows a shift to lower energy. For $n$-type GaAs at 300°K and $p$-type GaAs at 77°K, a combination of the two effects is observed. Fluorescence emission for the relatively low doped $n$-type GaAs occurs at nearly the energy of the band gap, while the highest doped materials emit at higher energies. The $p$-type fluorescence occurs through the acceptor state at 77°K, but not at 300°K. A deep level, presumably an acceptor level about 0.08 eV above the valence band, was found for Ge-doped GaAs.