Surface accumulation of tin in tin-doped gallium arsenide grown by low pressure metalorganic vapor phase epitaxy

Abstract
The surface accumulation of tin in low pressure metalorganic chemical vapor epitaxy (MOVPE) grown tin-doped GaAs layers has been investigated by secondary ion mass spectroscopy. Our results show that the surface enrichment factor for MOVPE grown layers is negligible for n≲5×1018 cm−3. For layers of higher doping densities this enrichment factor is smaller by more than an order of magnitude than that obtained for molecular beam epitaxy grown layers of comparable doping, in spite of the higher growth temperature used in MOVPE. A qualitative interpretation for the observed low surface enrichment factor is given.