Electronic modification of wet-prepared Si surfaces by a dichlorosilane reaction at elevated temperature

Silicon growth using chemical vapor deposition (CVD) is omnipresent in electronic device technology. CVD reactions of different precursor molecules on Si have been the focus of research for decades. Renewed interest in the CVD growth of silicon films has been spurred by the need for high-quality, ultrathin films for fabrication of novel electronic devices. In this work, we have formulated an experimental nanoscale approach to analyze the modification of wet-prepared Si(0 0 1) surfaces by dichlorosilane (SiH2Cl2, DCS) reactions at low pressure and 500–650 °C performed in a thermal CVD reactor connected to a scanning tunneling microscopy and spectroscopy (STM/STS) system. The DCS dissociation reaction resulted in a decrease of the Si surface potential due to the creation of chlorine-induced electric dipoles. Employing the ability of the scanning tunneling spectroscopy (STS) to recognize specific adsorption sites, we have carried out a comparative analysis of the relative coverage by Cl and Si as a function of exposure conditions. The existence of an intermediate reaction state of the DCS molecule was confirmed by the STS spectra and further supported by Si XPS data and ab initio calculations. This experimental nanoscale approach shows great promise for the CVD growth of ultrathin films.