Piezospectroscopy of the ground and excited states of zinc double acceptors in germanium

Piezospectroscopic midinfrared absorption studies of the neutral double acceptor Zn in Ge have been undertaken to determine the ordering and symmetries of the ground and excited states. The results are shown to be in excellent agreement with existing theoretical models of the double acceptor states, provided that the lowest-energy component of the split ground state has ${\Gamma }_1$ symmetry at zero stress. The experimentally determined deformation-potential constants for Zn agree well with those of the single acceptor Ga in Ge.