Mean free path of hot electrons at the surface of boron-doped silicon

Electrons can be injected from silicon into silicon dioxide in a metal-oxide-semiconductor-transistor (MOST) structure in which electrons are accelerated in the depletion layer of the channel region in a direction perpendicular to the Si-SiO2 interface. An analysis of the resulting oxide current as a function of the reverse voltage applied to the source and drain regions is carried out using an extension of a model proposed by Shockley. This leads to an estimate of the mean free path λ of the hot electrons in the silicon. It appears that a heavily doped source and drain, formed by a phosphorus diffusion, or the dislocations generated by this diffusion, have the effect of increasing λ by, presumably, the removal of scattering centers. The largest value of λ observed, λ=135 Å, is possibly equal to the value of the mean free path for the generation of high-energy phonons.