ATOMIC LAYER EPITAXY OF SI ON GE(100) - DIRECT RECOILING STUDIES OF FILM MORPHOLOGY

Two Si atomic layer epitaxy schemes based on Cl/H exchange chemistry a re compared by deposition of Si on Ge(100). Time-of-flight direct reco iling and reflection high-energy electron diffraction are used to char acterize the very thin Si layers. It is shown that alternating exposur e to SiCl2H2 and atomic hydrogen deposits Si in a process that is self -limiting. Growth of Si by this method results in either alloy formati on or Si island growth as low as 465-degrees-C on Ge(100), which prohi bits a simple measurement of Si thickness/cycle. In contrast, alternat ing exposure to Si2Cl6 and Si2H6 below 500-degrees-C results in Si dep osition with uniform thickness. Plots of direct recoil intensity versu s incident angle (with respect to the surface plane) are a sensitive p robe of the thin layer morphology.