Stress-induced anisotropy of phosphorous islands on gallium arsenide

The initial growth of (2x4) phosphorous islands on (4x2) terraces of galliu m arsenide (001) has been studied. The islands grow anisotropically in the [110] direction with an aspect ratio of approximately 8 to 1 at moderate co verages. The distribution of island widths in the [(1) over bar 10] directi on follows a Gaussian function. The mean width increases from 24 +/- 6 to 4 7 +/- 11 Angstrom as the phosphorous coverage increases from 0.10 to 0.85 m onolayers. Evidently, the island anisotropy is caused by stress imposed on the underlying gallium layer by the smaller, more tightly bound phosphorous dimers. (C) 2000 American Institute of Physics. [S0003-6951(00)01640-5].