Autocompensation in Si planar doped GaAs

The doping characteristics in Si planar doped GaAs grown by MBE are investigated. In order to study the cause of decrease of the sheet conductivity at a high doping level, the C-V and the SIMS profiles are measured for samples doped at 1.7 × 1012 up to 2.0 × 1013 cm-2. At low doping densities (NSi≦ 4.8 × 1012 cm-2), the C-V concentration is equ al to the SIMS concentration. In samples doped with NSi > 4.8 × 1012 cm-2, however, the C-V concentration is always lower than the SIMS concentration. The effect of the rapid thermal annealing was investigated and it was found that the increase of the sheet conductivity is accompanied by the increase of the C-V concentration. 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.