THERMAL AND CATALYTIC DECOMPOSITION OF SI2H6 ON A GE(100)2X1 SURFACE - PHOTOEMISSION AND LEED STUDIES

We present photoemission and LEED results concerning the thermal and c atalytic decomposition of disilane Si2H6 on a monocrystalline Ge(100)2 x 1 surface. The catalytic decomposition of disilane was obtained wit h a hot tungsten filament. Germanium substrates were heated by the Jou le effect in the 20-500-degrees-C temperature range and exposed to eit her catalytically decomposed or undecomposed disilane. The thicknesses of the Si deposited layers were estimated from X-ray photoelectron sp ectroscopy (XPS) measurements. The crystalline quality of the deposite d films could be controlled by angle resolved ultraviolet photoelectro n spectroscopy (ARUPS), X-ray photoelectron diffraction (XPD) and low energy electron diffraction (LEED). For a substrate temperature around 350-degrees-C, the exposures to undecomposed or catalytically decompo sed disilane lead to deposition of well-ordered Si thin films. At this substrate temperature, the Si growth rate was found to be 2-3 times h igher when #disilane was catalytically decomposed. At substrate room t emperature, while some authors claimed the adsorption of undecomposed disilane on a Ge(100)2 x 1 surface, our results seem to show that no r eaction occurs between undecomposed disilane and a Ge(100)2 x 1 surfac e. For substrate temperature above 400-degrees-C, the decrease of the Si photoemission intensities can be explained by an indiffusion of Si into Ge.