Samples of Ga0.7Al0.3As:Si/GaAs modulation-doped field-effect transistor-type hetero-structures were grown at temperatures of 500 and 620C. Three doping modes were used: -doping, pulse-doping, and uniform-doping. Deep-level transient spectroscopic measurements were performed, using a new Fourier analysis method. Up to 4 deep-level transient spectroscopy peaks, which were related to the various possible configurations of the nearest Al and Ga neighbors around each DX site, were observed. It was found that both the growth temperature and the doping method affected the spectra; in particular, the number of observed peaks and their width. The results were interpreted in terms of the differing mobilities of Si dopant atoms on the surface during growth.

Y.Haddab, M.A.Py, H.J.Bühlmann, M.Ilegems: Journal of Electronic Materials, 1994, 23[12], 1343-7