High Quality Ge Growth on Si (111) and Si (110) by Using Reduced Pressure Chemical Vapor Deposition

Abstract

A method for high quality epitaxial growth of Ge on Si (111) and Si (110) is investigated by reduced pressure chemical vapor deposition. Two step Ge epitaxy (low temperature Ge seed and high temperature main Ge growth) with several cycles of annealing by interrupting the Ge growth (cyclic annealing) is performed. In the case of Ge seed layer growth below 350 °C for (111) and 400 °C for (110) orientation, huge surface roughening due to too high dislocation density is observed after the following annealing step. For both crystal orientations, a high crystallinity Ge seed layer is realized by combination of 450 °C growth with 800 °C annealing. Once the high-quality Ge seed layer is deposited, high crystal quality Ge can be grown at 600 °C on the seed layer for both crystal orientations. For the 5 µm thick Ge layer deposited with the cyclic annealing process at 800 °C, a Si diffusion length of ~400 nm from the interface, RMS roughness below 0.5 nm and threading dislocation density of 5×106 cm-2 are achieved for both (111) and (110) substrates.