On the Shape of Electron-Hole Droplets in Highly Excited Anisotropic Semiconductors —Application to Uniaxially Stressed Ge and Si—

Abstract

Density functional formalism developed by Hoenberg, Kohn, and Sham is applied to the calculation of the surface tension of electron-hole droplets in anisotropic semiconductors. It is shown that the droplet warps because of the anisotropy of electron mass parameters. The shape of droplets in highly excited Ge under an uniaxial stress of about 0.3 kbar along the [111] direction is of the shape of oblate spheroid. The ratio of the minor axis to the major one is estimated to be 1.2∼1.9 under the assumption of local neutrality. The shape of droplets in Si under an uniaxial stress of about 1.5 kbar along the [111] direction is also shown to be oblate spheroid with the axis ratio less than 1.54. Determination of the shape of droplets by the light scattering experiment is discussed.