The perturbed angular correlation method (PAC) is applied to semiconductors. This technique is based on the detection of the electric quadrupole hyperfine interaction by means of radioactive nuclei. The highly localized sensitivity of the PAC-method favours the investigation of localized distortions of the lattice due to impurities as donor or acceptor atoms.
Results are given for radioactive 111Cd atoms in the semiconductors In2 Te5, ZnO, and Si. The observed electric field gradients (EFG) and their orientations with respect to the crystal axes yield information on the local structure around the probe atoms. In Na—or Li—doped ZnO the formed Na—O—In (or Li—O—In) complexes show identical axial symmetric EFG tensors. In the case of In2Te5 acceptor level energies could be deduced from the temperature dependence of the EFG.