Thin Film Polycrystalline Si by Cs Solution Growth Technique

Abstract

A deposition process has been developed which allows the growth of large grain (20⁺ μm) polysilicon films on SiO₂ substrates at a growth temperature of 650° C. A thin layer of liquid Si-metal solution is formed on the substrate surface as the growth medium. This layer is kept saturated by Si flux from a DC magnetron sputter gun. XRD analysis of the deposited films show a strong (111) preferred orientation, with increasing integrated peak intensities with increasing depositon temperature and solution layer thickness. Films deposited using an In-Si solution are p-type, with carrier concentrations in the mid 10¹⁶ cm⁻³ range. Conductivities of ∼.2 (Ω cm)⁻¹ were measured, with activation energies for both carrier generation and conductivity of about 135meV. The hole mobility was found to be ∼ 30 cm² V⁻¹s⁻¹. A wetting layer is used which may have a detrimental effect on the minority carrier lifetime.