ヘテロエピタキシャル成長における歪緩和と貫通転位の低減 : Si(001)基板上の高品質Si_<1-x>Ge_x歪緩和層の成長(<小特集>バルク成長分科会特集 : 結晶成長の科学と技術)

抄録

Propagation behavior of dislocations and surface morphological evolution are crucial factors to determine the quality of heteroepitaxial films on substrates. We report here a novel method applicable to form high-quality strainrelaxed Si_<1-x>Ge_x. buffer layers on Si(001) substrates. In this method, strain relaxation of the Si_<1-x>Ge_x layer is performed with two-step procedures consisting of high temperature annealing of the first pseudomorphic Si_<1-x>Ge_x layer and epitaxial growth of the second Si_<1-x>Ge_x layer on the partially relaxed first layer. The formation of a thin cap-layer before the annealing is effective in suppressing surface roughening during the annealing. In this case, penodic undulation formed on the second layer surface the key to enhancing the glide of threading terms of misfit dislocations, which results in a drastic reduction in the threading dislocation density.