Can electrical deactivation of highly Si-doped GaAs be explained by autocompensation?

Using near-edge x-ray absorption fine structure, the first experimental determination of Si atom concentrations occupying As sites in Si-doped GaAs (100) is reported. The measurements reveal that at high doping levels (≳1019 cm−3) in molecular-beam-epitaxy-grown samples, the number of such p-type Si atoms is insufficient to account for the observed large reduction of free-carriers.