Microcrystalline and polycrystalline silicon films for solar cells obtained by gas-jet electron-beam PECVD method

A new gas-jet electron beam plasma enhanced chemical vapour deposition (GJEB PECVD) method for high-rate deposition of crystalline silicon films is presented. The method is based on the activation of initial gas molecules in an electron beam plasma and fast convective transfer of the radicals to a substrate by means of a supersonic free jet. Nanocrystalline, microcrystalline and polycrystalline Si film growth on different foreign substrates is investigated using morphological and optical analyses in dependence on the temperature of the substrate and its distance from the nozzle. It is shown that a middle range of substrate distance is required to avoid crystallinity damage by heavy ions while still keeping their effect on grain nucleation. In this case, well shaped crystalline grains embedded with a 'highly ordered' amorphous phase are found in Si films grown at a low temperature at the edge of crystalline growth.