Formation and shape of InAs nanoparticles on GaAs surfaces

The conclusions of published experimental work that InAs deposited under As-rich conditions on GaAs(001) at 770 K forms nanoparticles whose flat surfaces are the {136} family of planes, whereas that InAs remains flat on GaAs(110), on GaAs(111)A but not on GaAs(111)B, are considered. It is shown that these results are consistent with the behavior of the crystallographically anisotropic surface tension of the strain-free solid on a molten monolayer, the liquid Phase being induced by solid phase heteroepitaxial stress. For the diamond structure, the surface tension is a minimum for (111) and a maximum for (001). Particle formation and shape depend on surface free energy minimization of the particle and substrate surfaces in conjunction. The molar entropy of liquid InAs at 770 K is calculated to be intermediate to that of the liquid and solid phases at the zero pressure melting point of 1215 K. (C) 1999 American Vacuum Society. [S0734-211X(99)12102-4].