Formation of self-assembled Si_1-xGe_x islands using reduced pressure chemical vapor deposition and subsequent thermal annealing of thin germanium-rich films

In this study, we report on the initial experimental results of formation of self-assembled Si_1-xGe_x islands by the selective chemical vapor deposition of highly strained Si_1-xGe_x thin films (with x to approximately 0.4) on patterned silicon wafers and the subsequent annealing of these thin films. Unlike previous studies, islands are formed during the thermal annealing of these thin films after the growth of the smooth continuous selectively grown thin films and not by direct growth of the islands. 50-160 angstroms Si_0.6Ge_0.4 films are selectively grown on silicon wafers with an oxide pattern using chemical vapor deposition from germane, silane and HCl at 650 °C and 40 Torr. In situ annealing of the films at 650-750 °C at 20-40 Torr for 6-25 min resulted in the formation of the islands. The size and distribution of the islands was found to be a function of the annealing conditions and an ordered pattern can be achieved with specific annealing conditions.