Effect of annealing temperature for Si0.8Ge0.2 epitaxial thin films

This study investigates the effect of annealing temperature on the Si0.8Ge0.2 epitaxial layers. The Si0.8Ge0.2 epitaxial layers were deposited by using ultrahigh vacuum chemical vapor deposition (UHVCVD) with different annealing temperatures (400-1000 °C). Various measurement technologies, including high-resolution X-ray diffraction (HRXRD), atomic force microscopy (AFM) and interfacial adhesion tester, were used to characterize the materials properties of the SiGe epilayers. The experimental results showed that the SiGe epilayers gradually reduced lattice-mismatch to the underlying substrate as annealing temperature increased (from 400 to 800 °C), which resulted from a high temperature enhancing interdiffusion between the epilayers and the underlying substrate. In addition, the average grain size of the SiGe films increased from 53.3 to 58 nm with increasing annealing temperature. The surface roughness in thin film annealed at 800 °C was 0.46 nm. Moreover, the interfacial adhesion strength increased from 476 ± 9 to 578 ± 12 kg/cm2 with increasing the annealing temperature.