Rutherford backscattering studies of strain-relaxed SiGe films grown on Si substrate with compositionally graded buffer layers

摘要

We investigated the structural properties of 2-μm thick Si_(0.58)Ge_(0.42) thin films grown on a combined set of Si_(1-x)Ge_x stepwise buffer layers and a Si_(0.51)Ge_(0.49) strain-inverted layer on Si substrates. Raman spectroscopy and Rutherford backscattering measurements showed smaller residual strain and superior crystalline lattice ordering compared to a sample without any buffer layer. Furthermore, a Si_(0.58)Ge_(0.42) thin film with a low dislocation density of less than 10~5 cm~(-2) and a smooth surface roughness of 0.903 nm can be achieved by using a combined set of Si_(1-x)Ge_x stepwise buffer layers and a Si_(0.51)Ge_(0.49) strain-inverted layer, because most dislocations can be confined within each Si_(1-x)Ge_x buffer layer.