Photoluminescence characterization of plasma exposed silicon surfaces

Abstract

The variation of photoluminescence (PL) spectra obtained with silicon exposed to various plasmas as a function of plasma etch treatment conditions is reported. Phosphorus- or boron-doped covering a large range of doping concentrations, Czochralski or float-zone-grown silicon crystals were investigated. The effect of various etching gases on the luminescence spectra as well as the effects of subsequent annealings are reported. Two types of recombination process are observed: (i) The first gives rise of sharp luminescence lines, such as the W (1018 meV), X (1040 meV), T (935 meV), I (965 meV), G (967 meV), C (790 meV), and P (767 meV) lines, which are known to originate from defects produced by high-energy irradiation and then manifest damage of the crystalline material. Other sharp PL lines at 1015, 1008, and 997 meV were introduced upon annealing at 400°C. (ii) The second recombination process induces broad lines or bands in the photoluminescence spectra. The formation and nature of the defects giving rise to both recombination processes are discussed in terms of the plasma conditions and starting material.