Journal of Crystal Growth, Vol.221, 581-585, 2000
Surface flattening during MOCVD of thin GaAs layers covering InGaAs quantum dots
Methods to re-establish a flat growth front on top of the corrugated surface of InGaAs quantum dots (QDs) during MOCVD are reported. Overgrowth temperatures at least 100 K higher than the low QD deposition temperature of 490 degreesC are required for a reduction of the corrugation. In order to avoid degradation of the QDs, however, the temperature must not be increased unless the QDs are buried by similar to 3 nm GaAs deposited at the QD growth temperature. Application of an additional annealing step after deposition of the GaAs cap layer improves the surface flatness and leads to an improvement of the radiative recombination efficiency. Lasers grown using such an annealing process for GaAs spacers of an InGaAs QD stack show lower threshold currents and higher internal quantum efficiency.