SiH 4 adsorption on SiGe(0 0 1)

Abstract

The adsorption process of silane (SiH 4) on a SiGe(0 0 1) surface has been investigated by using infrared absorption spectroscopy in a multiple internal reflection geometry. We have observed that SiH 4 dissociatively adsorbs on a SiGe(0 0 1) surface at room temperature to generate Si and Ge hydrides. The dissociation of Si- and Ge-hydride species is found to strongly depend on the Ge concentration of the SiGe crystal. At a low Ge concentration of 9%, Si monohydride (SiH) and dihydride (SiH 2) are preferentially produced as compared to the higher Si hydride, SiH 3. At higher Ge concentrations of 19%, 36%, on the other hand, monohydrides of SiH and GeH and trihyderide SiH 3 are favorably generated at the initial stage of the adsorption. We interpret that when SiH 4 adsorbs on the SiGe surface, hydrogen atoms released from the SiH 4 molecule stick onto Ge or Si sites to produce Si or Ge monohydrides and the remaining fragments of –SiH 3 adsorb both on Si and Ge sites. The SiH 3 species is readily decomposed to lower hydrides of SiH and SiH 2 by releasing H atoms at low Ge concentrations of 0% and 9%, while the decomposition is suppressed by Ge in cases of 19% and 36%.