AUTOCOMPENSATION IN SI PLANAR-DOPED GAAS

The doping characteristics in Si planar doped GaAs grown by MBE are in vestigated. In order to study the cause of decrease of the sheet condu ctivity at a high doping level, the C-V and the SIMS profiles are meas ured for samples doped at 1.7 x 10(12) up to 2.0 x 10(13) cm-2. At low doping densities (N(si) less-than-or-equal-to 4.8 x 10(12) cm-2), the C-V concentration is equal to the SIMS concentration. In samples dope d with N(si) > 4.8 x 10(12) cm-2, however, the C-V concentration is al ways lower than the SIMS concentration. The effect of the rapid therma l annealing was investigated and it was found that the increase of the sheet conductivity is accompanied by the increase of the C-V concentr ation. The ratio of the interstitial Si atoms to As sites Si atoms and Ga sites Si atoms is discussed on the basis of the results.