Optical spectroscopy of some axial and double acceptors in germanium

Zeeman and piezospectroscopic studies have been carried out on samples of germanium cut from single crystal ingots doped with ZnH acceptor complex. For Zeeman studies, magnetic fields were applied with strengths up to 6.5 T along,andcrystallographic directions. The spectra were obtained using the Voigt configuration. The effect of uniaxial stress on this complex has been studied for F||and. From the observed Zeeman and piezo transitions of the D line, the behaviour of the ground and excited states has been determined. The excited state behaviour of this complex is the same as that of the group III impurities in Ge. Though this complex constitutes a hydrogenic atom, the presence of H causes the ground state to be very different from that of unperturbed group III impurities. The observed ground state behaviour provides a template for identification of such axial defects. A new method was adopted to diffuse Mg into Ge. In the process, complexes were introduced. Zeeman studies were carried out with B||for two of these, viz., MgX1 and MgX2 . From the spectra, the Zeeman behaviour of the ground and excited state have been compared with that of ZnH complex which showed that these are also axial defects. Zeeman and piezo studies have been carried out along and directions respectively, for CuX complex. Observed spectra showed the axial nature of this complex is also like ZnH. This also explained previous Zeeman studies with B||. The effect of magnetic field on neutral magnesium double acceptor states has been studied for B||, confirming that the ordering of the ground state is the same as for neutral Zn. Also, a prediction is obtained of the Zeeman behaviour of the ground state of Mg-. This result is different than that for Zn-. A n attempt has been made to study the Zeeman effect of neutral beryllium in germanium; the magnetic field dependence of the G line for B|| has been observed using polarized radiation. The results are very complex, more experimentation being required to simplify the spectra.