Surface evolution in a pulsed laser induced epitaxy process of submicron SiGe wires

(100) Si substrates are patterned with arrays of Ge wires similar to 60 nm in width and similar to 6 nm in thickness. Pulsed laser induced epitaxy (PLIE) is used in an attempt to fabricate ultrasmall dimension Ge1-xSix wires. After laser irradiation, interesting changes on the surface are observed. In particular, ripples as high as similar to 30 nm are formed after the 6 nm Ge wires are incorporated into the substrate. The ripples decrease in height with further laser irradiation. The height is a function of the Ge wire width. Nomarski, scanning electron, atomic force, and cross-sectional transmission electron microscopy are used in the analysis. Possible explanations for the growth of the features are discussed.