We have investigated a new type of interaction between silane (SiH4) and borane (BH3) using high level ab initio calculations. The SiH4-BH3 complex is found to be extremely stable with the formation of a bridged hydrogen bond between SiH4 and BH3. Hence, it might have a hitherto unknown role in the mechanism of chemical vapor deposition (CVD), which is employed in the fabrication of boron doped silicon semiconductor materials. In an attempt to unravel this role and the underlying reasons responsible for the stability of this complex, we have carried out a detailed analysis based on the structure and molecular orbitals. The results indicate that the binding strength and electronic character of the bridged hydrogen bond in the SiH4-BH3 complex is between those observed in double hydrogen bridged B2H6 and mono-hydrogen bridged anion B2H7-. In contrast to B2H6 and B2H7-, it should be noted that the complex is stabilized by direct strong electrostatic interaction between the positively charged Si atom and the negatively charged B atom as well as by monobridged hydrogen bonding. Furthermore, we also note that the SiH4-BH3 complex would dissociate to form SiH3. and BH4. radicals. The existence of this complex is also inferred from good agreement between the calculated IR spectra and experimentally observed spectra of thin solid films of boron doped silicon semiconductor materials.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry