Temperature dependence of the linewidth of shallow impurity spectral lines in lightly doped weakly compensated semiconductors

Abstract

The broadening of spectral lines of intradonor absorption in n-GaAs is determined by random electric fields of charged donors and acceptors. The temperature dependence of the spectral line width reflects a redistribution of electrons over donors. At low temperatures the relative positions of charged and neutral impurities are strongly correlated by the Coulomb interactions in the system, whereas at high enough temperatures the distribution of electrons over impurities is random. This effect was recently suggested for quantitative characterization of semiconductors and a few theoretical attempts were made to describe the temperature dependence of the width of the spectral lines due to the transition from a correlated distribution of electrons to a random distribution in the low compensated material. We report here on the results of a Monte Carlo computer simulation of the transition. It is shown that the available analytical theories are not accurate enough and the reasons for such an inaccuracy are discussed.