The excitation and fano resonance spectra of some acceptors in silicon and germanium

Rich and well resolved p3/2 and p1/2 optical absorption spectra have been observed for indium in silicon and p3/2 spectra for singly ionised zinc, Zn-, in germanium, revealing some new transitions and permitting re-examination in detail of the transition energies, level schemes and deformation potential constants. Ratios of about 4.2 and 4.1 for the binding energies of Zn- in germanium to those of group III impurities and neutral zinc in germanium, respectively, were determined. A comparison with theoretical energies was made, showing excellent agreement. A set of asymmetric and broad excitation features was observed in the spectra of Zn- in germanium; these have a one-to-one correspondence with the p3/2 transitions and are separated from them by the zone centre optical phonon energy of bulk germanium. These new features have been identified as Fano resonances. The Fano resonance of the G line was found to be well defined, while the G line in the p3/2 spectrum is almost undetectable. This is the first observation of Fano resonances associated with bound holes in germanium. A simple and accurate method has been developed to deduce the parameters q, Γ and f of the resonances. The stress behaviour of the p3/2, p1/2 and Fano series of indium in silicon for Fll, and and of the p3/2 and Fano series of Zn- in germanium for Fll and and have been observed with linearly polarised radiation. The Fano resonances experience splitting under stress in a way similar to their counterparts p3/2 series. Their strengths, however, do not follow those of their p3/2 counterparts. piezo-Fano selection rules have been derived using group theory. A striking phenomenon for Zn- in germanium is the appearance of the some stress components of the Fano resonances for which their parents in the p3/2 series are strictly forbidden. is consistent with the selection rules which show how the rules for the p3/2 series are relaxed for this type of Fano resonance due to the mediation of the phonon.