High-resolution Laplace deep-level transient spectroscopy of Au- or Pt-diffused samples revealed an alloy splitting which was associated with alloying fluctuations in the proximity of the defect. In the case of the Pt acceptor state, the effect of the level splitting caused by alloying in the first and second shells of the surrounding atoms could be distinguished. In the case of the Au acceptor, only the effect of the first shell of atoms was observed. Alloying in the second-nearest shell was reflected by line-broadening. It was found that the electronic energy level was affected, by alloying in the first-nearest neighbourhood, by a factor which was 2 to 3 times greater than by alloying in the second-nearest shell. The absolute values of the energy differences which were deduced from Arrhenius plots for various defect configurations agreed with those which were deduced from the peak separations that were observed in the spectra. A clear preference of Au and Pt to enter substitutional Si sites adjacent to Ge was detected. This was explained in terms of enthalpy lowering; due to the fact that both metals were able to replace a host Si atom more easily than a Ge atom in the substitutional position.

High-Resolution Deep-Level Transient Spectroscopy Studies of Gold and Platinum Acceptor States in Diluted SiGe Alloys. K.Gościński, L.Dobaczewski, K.Bonde Nielsen, A.Nylandsted Larsen, A.R.Peaker: Physical Review B, 2001, 63[23], 235309 (10pp)