Growth and dissolution morphology of Ge crystals formed in GeI2-GeI4 vapor mixtures

Abstract

Abstract The growth and dissolution of Ge single crystals through disproportionation of GeI2 vapor are initiated by a sudden supersaturation change. The crystals have been observed in a quadratic fused silica pyramid whose flat transparent walls allow the automatic determination of the crystal contours from shadow pictures. The prominent macroscopic changes of the shape occur along the 〈111〉 directions. The steady-state growth form is thus mainly composed of {100} faces and the dissolution form of {111} faces. In a few cases, small as-grown {110} faces were also observed. Growth and dissolution proceed laterally via steps which run along the 〈110〉 directions. In the case of growth they move on the (001) face in the four 〈110〉 directions, and on the (111) face slowly in the 〈[unk][unk]2〉 directions and fast in the 〈11[unk]〉 directions. In the case of dissolution low and high steps move on the (111) face in the 〈[unk][unk]2〉 and 〈11[unk]〉 direction respectively.