Si + SiH4 Reactions and Implications for Hot-Wire CVS of a-Si:H
Richard P. Muller1,
Jason K. Holt2,
David G. Goodwin2,
and William A. Goddard, III1
1Materials and Process Simulation Center,
2Division of Engineering and Applied Sciences,
California Institute of Technology
Abstract:
Gas-phase chemistry is believed to play an important role in hot-wire
CVS of amorphous silicon, serving to convert the highly-reactive
atomic Si produced at the wire into a less-reactive species by
reaction with ambient SiH4. We use quantum chemical
calculations (B3LYP/cc-pVTZ) to examine the energetics and rates of
possible gas-phase reactions between Si and SiH4. The
results indicate that formation of triplet disilyne
(Si2H2) and molecular hydrogen is exothermic by
~2 kcal/mol with a low barrier. It does not require collisional
stabilization and thus can proceed at the low pressures characteristic
of hot-wire CVD. Other singlet species can also play a role but may
require collisional stabilization. Possible roles for singlet or
triplet disilyne in film growth will also be discussed.
Figure 1: Free Energies (at 2000 K) for reactions of Si and SiH4.
Richard P. Muller <rpm@wag.caltech.edu>
Last modified: Fri Feb 25 11:32:31 2000