Post-Growth Thermal Treatment of Self-Assembled InAs/GaAs Quantum Dots
GRENOBLE HIGH MAGNETIC FIELD LAB (FRANCE)
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Results of a post-growth rapid thermal annealing RTA on Gallium Arsenide GaAs proximity-capped structures with high density 10 cm-2 of self-assembled Indium ArsenideGallium Arsenide InAsGaAs quantum dots QDs are presented. Features of the QDs, bi-dimensional platelets 2DP, and InAs wetting layer WL were identified in a photoluminescence PL spectrum of the as-grown sample. Transmission electron microscopy shows that RTA at temperatures up to 700 degrees Centigrade for 30 seconds results in an increase of QDs lateral sizes. After RTA at 800 degrees Centigrade or higher temperatures, no QDs can be distinguished and substantial thickening of the WL can be seen. The main PL peak blueshifts as a result of RTA in all investigated temperature ranges, which is accompanied by a quenching of the 2DP and WL PL. It is proposed that the main PL peak, which is due to the QDs in the as-grown sample, results from optical recombination in the modified WL in the samples after RTA at 800 degrees Centigrade and higher temperatures. Laterally-enhanced GaIn interdiffusion induced by strain is proposed to explain a relatively fast dissolution of QDs. 5 figures, 25 refs.
- Solid State Physics