Effects of As/P exchange reaction on the formation of InAs/InP quantum dots

InAs self-assembled quantum dots (SAQDs) were grown on InP at various temperatures and V/III ratios by metalorganic chemical vapor deposition. The density, size distribution, and shape of the InAs SAQDs changed significantly with temperature and V/III ratio. Careful analysis of the total volume of the dots grown at various conditions showed that the volume far exceeded the amount of deposition supplied from the gas-phase sources. The amount of excess InAs and the aspect ratio (height/lateral size) of the SAQD increased with temperature and V/III ratio, strongly suggesting that the As/P exchange reaction at the surface played an important role in the kinetics of SAQD formation. Insertion of a lattice-matched InGaAs buffer layer suppressed the excess InAs formation, and lowered the aspect ratio, confirming the effect of the As/P exchange reaction. (C) 1999 American Institute of Physics. [S0003-6951(99)04114-5].