Characteristics of Heavily Si-Doped GaAs grown on (111)A Oriented Substrate by Molecular Beam Epitaxy as Compared with (100) growth

Abstract

Electrical and Optical characteristics of heavily Si-doped GaAs (111)A films grown by molecular beam epitaxy (MBE) were studied in comparison with those of (100) and (111)B films in relation to the occupation sites of dopant atoms determined by X-ray quasi-forbidden reflection (XFR) measurements. In the case of (100) growth, most of the doped Si atoms occupy Ga sites and the carrier saturation above [Si]∼6 × 10 18 cm -3 is dominantly caused by the formation of Si Ga complexes, not by compensation due to Si As acceptors. On the contrary, Si atoms in the (111)A films occupy As sites and act as acceptors up to [Si]∼6 × 10 19 cm -3 . At higher doping, they start to occupy Ga sites resulting in the saturation of carrier concentration.