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

摘要

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 degrees C for (111) and 400 degrees 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 degrees C growth with 800 degrees C annealing. Once the high-quality Ge seed layer is deposited, high crystal quality Ge can be grown at 600 degrees C on the seed layer for both crystal orientations. For the 5 mu m thick Ge layer deposited with the cyclic annealing process at 800 degrees C, a Si diffusion length of similar to 400 nm from the interface, RMS roughness below 0.5 nm and threading dislocation density of 5 x 10(6 )cm(-2) are achieved for both (111) and (110) substrates.