In situ visualization of traveling solvent growth of thin Si0.7Ge0.3 crystals

Abstract

A thin compositionally uniform silicon germanium crystal was grown by the traveling solvent method (TSM). In situ observation of the melting and crystal growth behavior with different temperature profiles was carried out to study the growth mechanism for the first time. It was found that the temperature gradient and the stability of melting interface was crucial for planar growth. Otherwise, the constitutional supercooling would induce faceted, and further dendritic growth. A temperature gradient of 1 K/mm was found suitable for planar growth. Above the critical temperature gradient of 1.4 K/mm, the growth interface became faceted. The stable growth velocity was also consistent with the theory indicating that the growth was driven by diffusion. From the electron backscatter diffraction (EBSD) analysis, it was confirmed that a single crystal was successfully grown from the seed. It was clarified that the strong segregation effect and positive concentration gradient from the seed side to the feed side caused solvent trapping in the faceted tips.