BibTex format
@phdthesis{Fraser:2009,
author = {Fraser, KJ},
title = {Impurity Gettering in Si Examined Using Cathodoluminescence},
year = {2009}
}
Publications
Citation
RIS format (EndNote, RefMan)
TY - THES
AB - Past work has shown that the luminescence efficiency of electronic grade silicon can be improved by gettering induced when samples containing ion implantation damage are annealed at ≥900C. This thesis presents an experimental and theoretical investigation of the gettering of metallic impurities in silicon using low-temperature (≤500C) annealing. At these low temperatures, the solubility of metallic impurities is low and consequently it was possible to perform the annealing in metallurgical furnaces rather than in expensive clean room conditions. An annealing scheme was designed consisting of three steps: 20-24 hours at 450 or 500C, a slow cool to 200C, then ~5 days at 200C. The different steps were intended to getter transition metal impurities with different values of solubility and diffusivity. A numerical model was created to simulate charge carrier generation, diffusion and recombination in cathodoluminescence (CL) experiments, in which luminescence occurs by recombination of electrons and holes produced by an incident electron beam. This model was used to calculate the effect on CL efficiency of changes in experimental conditions and sample properties. Modelling results indicate that in electronic grade silicon, gettering only affects the CL efficiency at shallow doping concentrations below ~10^17cm-3, and can only increase CL efficiency to a limited extent due to the effects of high excitation. Surface recombination is predicted to have a very strong effect on CL efficiency. CL experiments on as-grown and samples passivated by a thermal oxide showed strong agreement with the numerical model. Experimental procedures were refined to maximize reproducibility and reduce error. In particular, HF etching was used to standardize surface states between samples given different processing. Reference samples were used to standardize results from separate experiments. CL results obtained from samples subjected to the full low-temperature annealing scheme showed sign
AU - Fraser,KJ
PY - 2009///
TI - Impurity Gettering in Si Examined Using Cathodoluminescence
ER -