Nano-patterning and growth of self-assembled quantum dots

Different techniques for the preparation of patterned GaAs substrates for subsequent overgrowth are presented, including focused ion beam direct writing and laser holography followed by wet chemical or dry etching. GaAs-based buffer layers were grown on the patterns and consequently covered with self-assembled quantum dots (QDs). The effect of a strained InGaAs layer grown directly on the patterned substrates and its influence on QD formation and ordering is shown. The dot density, lateral distribution and size distribution of the dots are measured using atomic force microscopy. A comparison of the growth of QDs on patterned and unpatterned substrates indicates that on patterned substrates a higher QD density at the same InAs deposition can be achieved.