ARSENIC CLUSTER SUPERLATTICE IN GALLIUM-ARSENIDE GROWN BY LOW-TEMPERATURE MOLECULAR-BEAM EPITAXY

Molecular-beam epitaxy at 200 degrees C is used to grow an InAs/GaAs s uperlattice containing 30 InAs delta-layers with a nominal thickness o f 1 monolayer, separated by GaAs layers of thickness 30 nm. It is foun d that the excess arsenic concentration in such a superlattice is 0.9 x 10(20) cm(-3). Annealing the samples at 500 and 600 degrees C for 15 min leads to precipitation of the excess arsenic mainly into the InAs delta-layers. As a result, a superlattice of two-dimensional sheets o f nanoscale arsenic clusters, which coincides with the superlattice of the InAs delta-layers in the GaAs matrix, is obtained. (C) 1998 Ameri can Institute of Physics. [S1063-7826(98)00310-X].