Spectroscopic Study of the Deformation-Potential Constants of Group-III Acceptors in Germanium

The effect of uniaxial compression on the excitation spectra of group-III impurities in germanium is presented and discussed. The deformation-potential constants $b^{\prime }$ and $d^{\prime }$ for the ground states are deduced on the basis of the piezospectroscopic effects for the $C$ and $D$ lines. Although there is a slight chemical-species dependence of $b^{\prime }$ and $d^{\prime }$, the average values of these are - 1.4 and - 2.5 eV, respectively. These, in turn, lead to the values of - 2.5 and - 4.1 eV for $b$ and $d$, the corresponding parameters for the valence band, using the relationships given by Bir et al. The values of $b$ and $d$ thus calculated agree in sign and magnitude with those determined by other methods. This is in contrast to the results obtained on the basis of the previous interpretation, in which the final state of the $B$ line is assumed to have ${\Gamma }_7$ symmetry.