The influence of phonons and impurities on the broadening of excitonic spectra in gallium arsenide

Abstract

Abstract The absorption spectra near the fundamental edge of gallium arsenide are measured in the temperature range of 4.2 to 500 K on samples with concentration of charged impurities from 10 14 to 10 19 cm −3 . The description of the experiment by phenomenologically broadened theoretical spectra enables to determine the broadening parameter as a function of temperature and impurity concentration. The comparison of the results obtained with microscopic theories shows the interactions of excitons with longitudinal optical phonons and charged impurities to be the main broadening mechanisms. A semiempirical equation is obtained which permits to calculate the broadening parameter in gallium arsenide for a given temperature and impurity concentration.