Role Of Surface Instability And Anisotropy On Strain Relaxation Of Sige On Si(110)

Abstract

AbstractSiGe alloys (< 1.5 % mismatch) were grown on Si (110) substrates at 700°C by molecular beam epitaxy. The structure and surface morphology were studied as a function of SiGe coverage (1.5mn–9nm) using atomic force microscopy, transmission electron microscopy and RHEED. A very high density of nanoscale SiGe ledges (less than 1 nm high and 1 μm long) were observed to form on the step terraces created during buffer layer growth. An interesting phenomenon is that the step bunches generated by the buffer growth and SiGe ledges are aligned along the elastically hardest <111> direction on the Si (110) surface. With increasing alloy thickness, the nanoscale SiGe ledges become longer and straighter. The effects of the surface instability and elastic anisotropy on the elastic relaxation effects are discussed.