NONRADIATIVE RECOMBINATION AT GAAS HOMOINTERFACES FABRICATED USING ANAS CAP DEPOSITION REMOVAL PROCESS/

GaAs homointerfaces have been grown by molecular beam epitaxy using th e steps of GaAs growth, As cap deposition, wafer storage, thermal deso rption of the As cap, and GaAs overgrowth. As cap layers with a thickn ess of up to 7.8 mu m were deposited and the wafers were stored for 3- 7 days in ultrahigh vacuum (UHV) or under atmospheric conditions. Nonr adiative recombination originating from the GaAs homointerface of wafe rs stored in UHV could not be detected (interface recombination veloci ty S much less than 1000cm/s), however, significant nonradiative recom bination (S = 10(4)-10(5) cm/s) was found for all GaAs homointerfaces where wafer storage occurred under atmospheric conditions. This result demonstrates that the As cap deposition/removal process is inadequate for GaAs surface protection in a fabrication facility. (C) 1998 Ameri can Institute of Physics.