Exposure of GeH4 on Si was attempted at various temperatures to establish growth conditions for high-quality Ge on Si or Si-on-insulator, which could be utilized for on-chip 1.3-1.55 μm photodetectors. The grown film was found to be not pure-Ge but Ge-rich SiGe, and Si composition in the film increased with the rise of the growth temperature. This behavior could be utilized for growth of Ge on a compositionally graded SiGe buffer layer just by decreasing growth temperature. In fact, a preliminary experiment in order to obtain such a structure was successfully demonstrated by decreasing temperature from 700 to 500 °C at a rate of - 6.7 °C/min.
- Gas-source molecular beam epitaxy
- Raman spectroscopy