SIZE DISTRIBUTION OF COHERENTLY STRAINED INAS QUANTUM DOTS

The influence of the InAs coverage on the size and density of coherent ly strained InAs islands was investigated. At moderate InAs coverages the photoluminescence signal reflects the Gaussian size distribution o f small coherently strained islands. However, before the coherently st rained islands transform into dislocated ones the Gaussian line shape of their photoluminescence signal changes and a narrow peak appears on the low-energy tail. We attribute this change to an accumulation of c oherently strained islands at a maximum size before dislocated island transformation occurs. Effects of luminescence from dislocated islands , size-dependent relaxation processes, capture efficiencies, and dot-d ot coupling are also discussed. However, our calculations and the magn etophotoluminescence, as well as the photovoltage experiments, confirm our interpretation of a size accumulation process of coherently strai ned islands. (C) 1998 American Institute of Physics. [S0021-8979(98)10 020-8].