STRAIN RELAXATION AND SELF-ORGANIZING MBE-GROWTH OF LOCAL SIGE-STRUCTURES

SiGe wires and dots of mu m size were fabricated by a self-organizing MBE growth mode. Layer thickness and Ge content on top of a Si mesa bu ffer are varied. It is shown that defect free growth exceeding the cri tical thickness is possible for locally grown mesa structures. Raman s pectroscopy exhibits reduced strain relaxation for decreasing lateral dimensions, The SiGe-growth on the top of a locally grown Si buffer la yer results in the nucleation of dislocations mainly in the Si buffer, This effect of defect accumulation in the locally grown buffer offers a method for the fabrication of relaxed, defect free virtual substrat es.