Arsenic passivation of GaAs and pyrolytic decomposition of organotin compounds for in situ selected area doping of GaAs molecular beam epitaxy

Development of in situ selected area doping techniques would add a powerful new dimension to GaAs MBE technology. We report here a study of an in situ selected area doping procedure based on the following steps: (i) MBE growth of GaAs on a clean GaAs (001) substrate, (ii) adsorption of an As passivation cap which would be patterned for selected area doping, (iii) adsorption of an organotin compound, (iv) thermal desorption of the organotin compound along with the As cap in the passivated areas and with pyrolytic decomposition of the organotin compound in the unpassivated regions, and (v) regrowth of GaAs with selected area Sn incorporation into the regrowth layer. In this study we evaluated steps (iii)–(v). Steps (iii) and (iv) were investigated by means of in situ Auger electron spectroscopy, and step (v) by electrolytic C–V profiling of the carrier concentration. The organotin compounds in this study were tetrabutyltin and dibutyltin dibromide.