DEPENDENCE OF THE INTERFACE SHARPNESS OF A GE SINGLE-QUANTUM-WELL ON MOLECULAR-BEAM-EPITAXIAL GROWTH-CONDITIONS

The influence of molecular-beam-epitaxy growth conditions on the properties of five monolayers of germanium, embedded in a (001) silicon matrix for a conventional as well as an antimony-mediated growth in the temperature region from 300 to 450 °C, was investigated. The layers were analyzed by electroreflectance (ER), Raman spectroscopy, and transmission electron microscopy; they show compatible results for all three methods of investigation. For growth without antimony, a tendency toward segregation-induced alloying with increasing growth temperatures was observed. Antimony-mediated growth experiments show that the surfactant is able to improve the bulk character of the germanium layer at higher temperatures only, while it does not significantly influence the layer growth at lower temperatures. Among all investigated growth conditions the best sharpness of the germanium layer interface was found for the antimony-mediated growth at 450 °C. An annealing after growth at increasing temperatures increased the alloying by an interdiffusion of Si and Ge as indicated by Raman measurements. In ER a vanishing of the Ge-like transitions was observed after a treatment at temperatures between 600 and 700 °C for 15 min. © 1994 American Institute of Physics.