ELECTRON DEGRADATION AND THERMALIZATION IN SIH4 GAS

The time-dependent Boltzmann equation is applied to the study of the degradation and thermalization of a nonequilibrium distribution of subexcitation electrons in SiH4. For the small electron to SiH4 mass ratio, the collision operators in the Boltzmann equation reduce to the differential Fokker-Planck operator for elastic collisions and the difference operator for inelastic collisions. A finite difference method of solution of the Boltzmann equation is used. The time evolution of the electron energy distribution and the thermalization time of subexcitation electrons are calculated for initial electron energies of 1, 3 and 5 eV. It is shown that super elastic collisions due to vibrational de-excitation play an important role in the thermalization process.