Formation and characterization of ultrasmall dimension GeSi wire structure by using pulsed laser-induced epitaxy

(100)Si substrates are patterned with arrays of Ge wires ∼60 nm in width and ∼6 nm in thickness. Ultrasmall dimension GeSi surface wire structures are then formed in Si in a pulsed laser-induced epitaxy process. The wire structures are analyzed by secondary electron microscopy, atomic force microscopy, Auger electron spectroscopy, and cross-sectional transmission electron microscopy. No defects are observed in the wires structures. However, significant side diffusion of Ge, much more than the vertical diffusion occurred during the ∼40 ns pulsed laser-induced epitaxy process, is observed in the Si substrate. Surface evolution is also observed. Possible explanations for the abnormal Ge side diffusion are discussed.