Ultralow temperature ramping rate of LT to HT for the growth of high quality Ge epilayer on Si (1Â 0Â 0) by RPCVD

An approach to grow high quality strain-relaxed Ge on silicon (1 0 0) substrate has been proposed using a modified two-step growth method by reduced pressure chemical vapor deposition system. The modified Ge growth method consists of the low temperature growth at 400 °C, intermediate temperature growth from 400 to 600 °C with low ramping rate and high temperature growth at 600 °C. The post-growth anneal in hydrogen at 800 °C was introduced immediately after the Ge growth. For the Ge epitaxial film grown with low temperature ramping rate of 6 °C/min, the root mean square roughness is 0.621 nm in 10 × 10 μm2 scan field, and the threading dislocation density (TDD) is 3 × 106 cm−2 with the film thickness of about 1.3 μm. Furthermore, in contrast to the epitaxial Ge sample grown with the high temperature ramping rate of 140 °C/min, intermediate low temperature ramping rate from 400 to 600 °C is advantageous in terms of TDD reduction, as well as maintaining smooth surface morphology in Ge epilayer.