Crystal orientation in microcrystalline SiGe alloy films deposited by sputtering-plasma CVD

Crystal orientation was studied for films of microcrystalline SiGe alloys (μc-SixGe1-x) prepared at low substrate temperatures by RF sputtering of Ge target in SiH4 gas diluted with H2. The composition x of SixGe1-x alloy was controlled either by changing the substrate temperature Ts or the flow rates [SiH4/(SiH4 + H2)]. It was found from X-ray diffraction measurements that the (220) orientation increased remarkably at substrate temperatures above 300 ∼ 350 deg C. The maximum ratio of (220) peak height to (111) peak height increased to nearly 90 at the substrate temperature of 420 deg C. The (220) orientation was most notable when the composition was nearly 0.5. (author)