Shallow Acceptor States in ZnTe and CdTe

The group $\mathrm{V}A$ element P and the group $\mathrm{I}A$ elements Li and Na give rise to shallow acceptor centers in ZnTe and in CdTe. An analysis of the carrier concentration data for Li-doped ZnTe and P-doped ZnTe on the basis of a single-level acceptor and nondegenerate statistics indicates that P and Li produce shallow, hydrogenic-type acceptor levels in ZnTe. Annealing studies demonstrate that the shallow levels in Li-doped ZnTe and CdTe may be removed by heat treatment at 250°C for tens of hours. The concentrations of shallow acceptors in P-doped ZnTe and Na-doped ZnTe are relatively unchanged by the annealing procedure. The effective mass for holes in ZnTe as deduced from the Hall analysis is $0.36m$, where $m$ is the free-electron mass.