The electrical activity of defects in GaAs p+n diodes that had been grown onto Si or GaAs substrates by using conventional molecular beam epitaxy or atomic H-assisted molecular beam epitaxy, was investigated by means of deep-level transient spectroscopy. The electron traps which were typical of molecular beam epitaxial GaAs were detected, without the corresponding presence of any new levels in the upper half of the band gap. It was found that the trap densities were significantly reduced in homo-epitaxial GaAs that had been grown by using H-assisted molecular beam epitaxy, as compared with that which had been grown by means of conventional molecular beam epitaxy. The trap densities in hetero-epitaxial GaAs/Si which had been grown by means of H-assisted molecular beam epitaxy were higher than those in homo-epitaxial GaAs which had been grown by means of H-assisted molecular beam epitaxy at 330C. The reduction in trap density was attributed to the  in situ  passivation of those defects, by atomic H, during growth.

Y.Okada, J.S.Harris, W.Götz: Journal of Applied Physics, 1996, 80[8], 4770-2