SIZE QUANTIZATION PATTERNS IN SELF-ASSEMBLED INAS GAAS QUANTUM DOTS/

Molecular beam epitaxy has been used for growing self-assembled InAs q uantum dots. A continuous variation of the InAs average coverage acros s the sample has been obtained by properly aligning the (001) GaAs sub strate with respect to the molecular beam. Excitation of a large numbe r of dots (laser spot diameter approximate to 100 mu m) results in str uctured photoluminescence spectra; a clear quantization of the dot siz es is deduced from the distinct luminescence bands separated in energy by an average spacing of 20-30 meV. We ascribe the individual bands o f the photoluminescence spectrum after low excitation to families of d ots with roughly the same diameter and heights differing by one monola yer.