Role of H2 supply for Sn incorporations in MOCVD Ge1−xSnx epitaxial growth

Abstract

In this paper, we propose a new method of using H2 supply in the atmosphere to increase Sn concentration in a Ge1−xSnx film epitaxially grown on a Ge substrate using MOCVD (metal organic chemical vapor deposition). H2 supplied in the atmosphere accelerates decomposition of Sn precursors and suppresses surface migration of Sn atoms during epitaxial growth of a Ge1−xSnx film. The proposed method is new and fundamentally different from the existing methods that increase Sn concentration through either crystallizing α-Ge1−xSnx or lowering growth temperature. The proposed method uses H2 supply in the atmosphere to increase Sn concentration.In order to show the effectiveness of the proposed method, we conducted experiments with varying ratios of supplying H2 in the atmosphere and epitaxially grew a Ge1−xSnx film on a Ge substrate using MOCVD. MO precursors that we used in our experiments (tertiarybutylgermane and tetraethyl tin) are new and safe. In our experiments, we observed that Sn concentration increased with H2 supply during growth, while maintaining a high growth rate of a Ge1−xSnx film.