Nucleation and growth of InAs quantum dots on GaAs[001]

The formation of dislocation-free quantum dots (QDs) in material systems such as InAs/GaAs has attracted great interest because of the novel optoelectronic properties of QDs and their potential uses for device applications. However, some fundamental aspects of QD formation such as the exact nature of the 2D-3D growth mode transition at the critical coverage (/spl theta//sub crit/) remain poorly understood. Our detailed scanning tunneling microscopy (STM) studies of InAs/GaAs[001] growth as a function of InAs coverage (/spl theta/) provide the first direct evidence for the existence of small 3D precursors in QD formation. Scaling analysis of QD size distributions shows that strain is only a significant factor in the initial stages of QD growth. These results are in disagreement with previous studies of InAs/GaAs[001] QD growth.