Growth of high-Sn content (28%) GeSn alloy films by sputtering epitaxy

Crystalline GeSn thin films with Sn content up to 0.28 were deposited on Sn graded GeSn buffer on a Ge substrate at low temperatures by sputtering epitaxy. The structural properties of the high-Sn content GeSn alloy films were characterized by high resolution transmission electron microscopy and X-ray diffraction. The effect of annealing on the segregation of Sn in the high-Sn content GeSn film was investigated, and both the Ge0.72Sn0.28 and the Ge0.8Sn0.2 films were found to be stable after annealing at temperatures below 400 °C, which meets the needs of thermal budget for future photonic devices fabrication. The present results indicate that sputtering epitaxy is cost-effective method for growing high-Sn GeSn films.