Ultrathin low temperature SiGe buffer for the growth of high quality Ge epilayer on Si(100) by ultrahigh vacuum chemical vapor deposition

The authors report a method to grow high quality strain-relaxed Ge on a combination of low-temperature Ge seed layer on low temperature ultrathin Si 0.8 Ge 0.2 buffer with thickness of 27.3 nm by ultrahigh vacuum/chemical-vapor-deposition method without the need to use chemical mechanical polish or high temperature annealing. On 8 in. Si wafer, the etch-pit density was 6 × 10 6 cm − 2 . The root-mean-square surface roughnesses of Ge epitaxy by atomic force microscopy were 1.4 and 1.2 nm for bulk Si and silicon-on-insulator substrates, respectively. Micro-Raman spectroscopy shows extremely uniform distribution of residual strain in the overgrown Ge epitaxy on 8 in. wafers.