The shape of self-assembled InAs islands grown by molecular beam epitaxy

We have determined the shape of InAs quantum dots using reflection high ene rgy electron diffraction. Our results indicate that self-assembled InAs isl ands possess a pyramidal shape with {136} bounding facets. This shape is ch aracterized by C-2 upsilon symmetry and a parallelogram base, which is elon gated along the [1(1) over bar 0] direction. Cross-sectional transmission e lectron microscopy images taken along the [110] and [1(1) over bar 0] direc tions as well as atomic force microscopy images strongly support the {136} shape. Furthermore, polarization-resolved photoluminescence spectra show-st rong in-plane anisotropy, with emission predominantly polarized along the [ 1(1) over bar 0] direction, consistent with the proposed quantum dot shape.