Inhomogeneous Line Broadening in Donor Magneto-Optical Spectra

Abstract

We discuss inhomogeneous broadening of the spectral lines of shallow neutral donors in a magnetic field. The broadening arises from electric fields and field gradients produced by donor and acceptor ions in partially compensated semiconductors of high purity. On the assumption that the ions and neutral donors are randomly distributed in the semiconductor, line shapes are calculated and compared to observed line shapes in GaAs. Using the ion concentration as an adjustable parameter, we are able to account quantitatively for a number of observed effects on the random impurity model, but are led to suggest that some weak pairing between donor and acceptor ions is probably present.