Characterization of epitaxial heavily doped silicon regions formed by Hot-Wire chemical vapor deposition using Micro-Raman and microphotoluminescence spectroscopy

We report on the characterization of heavily boron doped epitaxial silicon regions grown in a hot-wire chemical vapor deposition tool, using micro-Raman and photoluminescence spectroscopy. In particular, the use of this approach for emitter fabrication in an interdigitated back contact silicon solar cell is studied, by analyzing its suitability concerning selective growth, uniformity, anneal time, and luminescent defects. We show that by reducing the silane flow rate, both the required postanneal time and intensity of defect luminescence are reduced. Furthermore, we show that selective area growth does not affect either the quality of the films or the sharpness of the resulting lateral doping profile. The uniformity of the doping is shown to be better than that achieved using laser doping.