Year

2001

Degree Name

Doctor of Philosophy

Department

Faculty of Engineering

Abstract

Quantitative piezo- and temperature dependent spectroscopy have been carried out on antimony in germanium. Here the behaviour of the unperturbed spectrum with temperature is followed in much more detail than previously. The changes in the energies and intensities of spectral lines with temperature show that the spacing of the chemically split ground state, 4ΔC, is slightly temperature dependent. The variation in intensities of spectral lines from the split ground state to a common excited state is shown to obey the Boltzmann distribution for the relative populations of the two ground substates.

The application of stress along a direction for Sb in Ge revealed dramatic changes in the intensities of the spectral components with stress. The relatively small chemical splitting of the ground state allowed the stress dependence to be examined in the high stress limit (HSL) using relatively small stresses. In the HSL, depopulation of the upper ground substates combined with transition probabilities resulted in only the p0 (1)(-) transitions to be observed with E||F, while for EF, only the p±(1)(-) are seen. Here E is the direction of polarisation of the electric field vector of the radiation incident on the sample and F is the applied compressive force. Consequently, there are nine p0 (1)(-) transitions observed in the HSL with E||F; this is six more than has been previously observed. With EF, there are seven p±(1)(-) transitions seen. These results also provide experimental verification of previously predicted stress dependent energy and intensity changes at low stresses.

Piezo- and Zeeman spectroscopy have been carried out on aluminium in germanium. The piezospectroscopic study was carried out on all transitions from the G to the A1 with stress applied along both and directions. These results showed good agreement with previous results for the G, D and C lines, and with theoretical results. This study provides an unambiguous identification ofthe final states ofthe B, A4, A3, A2 and A1 transitions. Deformation potential constants b' and d' were determined for all Γ8 transitions of the lines studied, with good agreement being obtained with previous experimental and theoretical results.

Zeeman spectroscopy of Al in Ge was carried out for magnetic fields, B, up to 6.5T. These studies involved the examination ofthe G and D lines with B along , and directions. Also studied were the C and B lines with B|| for fields up to 2 T. The above results were compared with two theoretical results, with the excited state ofthe D line giving excellent agreement. The excited states of the G, and B lines gave good agreement. There was significant disagreement between the theories themselves and the experimental results for the ground state for all orientations of B.

The g-factors of the ground state and the excited states of the G, D, C and B lines were determined. Comparisons between these g-factors and those of theoretical and experimental results of other group III acceptors were made.

Qualitative results are presented of the variations in intensity of spectra with different orientations of E when EB||. This was done with E|| and E||.

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