Investigation of the Electronic Thermal Transport in Thin Silicon Films with Varying Electric Field and Doping Concentration

Abstract

Scatterings of electrons by ionized impurities in semiconductors have been comprehensively explored by various methods. However, the electron-impurity scattering was not investigated under an electric field at thin silicon (Si) films. The effects of electric field on electronic thermal conductivity in thin Si films at different doping concentration at room temperature are investigated by using an analytical model based on the Boltzmann transport equation with the relaxation time approximation. As expected, the electronic thermal conductivity increases as the external electric field increases. More importantly, we show that the scattering between carrier and impurity is a dominant scattering mechanism in Si films at high doping level such as above 10¹⁸ cm^-3 under the influence of an electric field. The effect of the electron-phonon interaction on the electronic thermal conductivity of silicon can be neglected because electron mean free path is significantly reduced due to the impurity scattering and the effect of electric field. Since there is no experimental attempt to measure the electron and the phonon thermal conductivities with the electric field applied, the result is given of some simplified concepts that will contribute to a better understanding of electron transport fundamentals.