The nucleation stage of GaAs/Ge growth was investigated for growth rates which ranged from 2 to 20/h. Almost perfect surface morphologies could be obtained on samples, that were thicker than the critical thickness for the generation of misfit dislocations, at a deposition rate of 16/h. It was shown that V-shaped defects, which were typically found in GaAs/Ge low-pressure metalorganic vapor-phase epitaxially-grown heterostructures, could be eliminated by using a low V/III ratio. The growth rate of solar-cell buffer layers was found to play an important role in increasing the open-circuit voltage of the device. The occurrence of the cascade effect was considered, and the effect of the misfit dislocation density upon the open-circuit voltage was demonstrated.

G.Timò, C.Flores, R.Campesato, D.Passoni, B.Bollani: Materials Science Forum, 1996, 203, 97-102