Infrared absorption bands induced by Si-related defects in GaAs: Absorption cross sections

Silicon is an amphoteric impurity in GaAs and is present in different defect configurations. This work reports measurements of the infrared absorption cross sections for some of the localized vibrational mode bands related to the Si defects. Heavily doped melt-grown samples are used to measure the free-carrier density ne and the integrated absorption of all bands attributed to electrically active defects. The resulting data are analyzed by using a least-squares-fitting procedure employing two different models. A set of absorption cross sections is given for each model. These results differ from others reported recently. Using the two sets of cross sections to interpret the absorption spectra of p-type liquid-phase epitaxial samples seems to reaffirm a previously reported interpretation in which an additional Si-related acceptor defect of unknown nature is present.