The growth of layers, using molecular beam epitaxy, was carried out while the substrate was held at a floating, positive or negative bias, in order to investigate the effects of ion bombardment upon crystalline quality. It was found that, although the ion energies (100 to 1500eV) and ion/atom flux ratios (equal to about 0.005) which were used were quite low, a significant lattice distortion existed along the growth direction; as revealed by high-resolution X-ray diffraction from Si layers which had been grown at 420C. At the same time, a broad-band transition was observed in the photoluminescence from both Si and SiGe layers. On the basis of the annihilation behavior during post-growth treatment, using thermal annealing and hydrogenation, these effects were attributed to the bombardment-induced formation and injection of various types of point-like defects and defect clusters which degraded the optical and electrical properties of grown layers.

W.X.Ni, G.V.Hansson, I.A.Buyanova, A.Henry, W.M.Chen, B.Momemar: Applied Physics Letters, 1996, 68[2], 238-40