A RAMAN-SPECTROSCOPIC STUDY OF THE SI, BE, AND C INCORPORATION IN INXGA1-XAS RELAXED LAYERS

The incorporation of high concentrations (>10(19) cm(-3)) of Si, Be, a nd C in InxGa1-xAs relaxed layers has been studied as a function of In content (x less than or equal to 0.16) by Raman spectroscopy of local vibrational modes (LVM). The frequencies of the Raman peaks resulting from the convolution of several split modes shift to lower values as the In content is increased, the carbon acceptor (C-As) local mode fre quency showing the strongest dependency on x. Features attributed excl usively to the influence of In on second-neighbor sites are identified only in the Si-doped samples. The transverse and longitudinal modes e xpected from the splitting of a LVM of C-As with one In first neighbor are not observed in layers with x up to 0.085. A new calibration for the Be-Ga, C-As, and Si-related LVM leads to the conclusion that In in creases the total electrical activation of Si and favors its incorpora tion on group-III sublattice sites. In contrast, no influence of In on the Be or C doping activation has been detected. The analysis of the C-As LVM spectra supports the view that in InxGa1-xAs C-As is preferab ly surrounded by Ga instead of In atoms for x less than or equal to 0. 085. (C) 1995 American Institute of Physics.