Spectroscopic Investigation of Acceptor States in Aluminum Antimonide

Photoexcitation spectra associated with acceptors in $p$-type aluminum antimonide have been studied. Four sets of sharp photoexcitation lines are observed at liquid-helium temperature; they are absent at liquid-nitrogen or higher temperatures. Equal spacings between pairs of prominent lines in three of these spectra are consistent with an effective-mass-like description for the excited states. The effect of uniaxial stress on several of the acceptor photoexcitation lines has been studied for compressive force F parallel to $〈111〉$ or $〈100〉$. The splittings and the polarization patterns may be interpreted if it is assumed that the acceptor centers have $T_d$ site symmetry, and that the bound hole states are not sensitive to a possible departure from a germaniumlike valence band with its maximum at k=0.