INAS QUANTUM DOTS IN GAAS HOLES - ISLAND NUMBER DEPENDENCE ON HOLE DIAMETER AND CONDUCTION-BAND COUPLING ESTIMATES

We studied the formation of InAs islands in holes defined by electron- beam lithography on GaAs substrates. The islands grew selectively in t he holes, with one to nine islands per hole. The number of islands dep ends simply on the hole diameter, filling the holes at a constant effe ctive two-dimensional density. We define the ratio of this effective d ensity to the density on an unpatterned control sample to be the selec tivity ratio, and we find a selectivity ratio of greater than 1000 for the present samples. We estimated the lateral conduction-band couplin g for closely spaced islands and conclude them to be plausible candida tes for weakly coupled device building blocks. (C) 1998 Academic Press Limited.