GROWTH-PROCESSES IN THE INITIAL-STAGES OF DEPOSITION OF GE FILMS ON (100)SI SURFACES BY GEH4 SOURCE MOLECULAR-BEAM EPITAXY

Growth process in the initial stages of deposition of Ge films on (100)Si surfaces by GeH4 source MBE has been studied by in-situ reflection high energy electron diffraction (RHEED) observation. The growth mode is of the Stranski-Krastanov type, and the strained monolayer overgrowth on the substrate surfaces takes place over the observed temperature range of 300-600 C. The growth behavior in the nucleation and island growth stages is found to change strikingly near 500 ° C. The activation energy of the growth rate above 500 ° C (0.24 eV) is 10 times as large as than that below 500 ° C (0.023 eV). In spite of these marked differences, the predominant facets of the growing islands is {8111}Ge planes initially and this changes to {311}Ge eventually with growth in the two temperature ranges. Half-order streaks associated with a (2×1) structure are observed to incline to 〈811〉Ge in the diffraction patterns. This analysis gives information on the atomic arrangement of {811}Ge. © 1990.