Large area and rapid thermal zone melting crystallization of silicon films on graphite substrates for photovoltaic use

Crystallized silicon thin films deposited on a low cost substrate have the potential to be applied for thin film solar cells. Silicon films, deposited on graphite substrates by sputtering or by the pyrolytic decomposition of silane (CVD), have been crystallized from the liquid phase. The line shaped molten zone is created by the radiation of a line electron beam and is moved at constant scan velocity (23 mm/s) across the graphite substrate. During the crystallization process silicon carbide forms preferentially at gaseous inclusions in the silicon. Schottky-diodes were fabricated on the crystallized silicon film. The crystallized silicon films were found to be unintentionally p-doped with a dopant concentration of p=5*10¹⁷ cm^-3 (sputter deposited) and p=8*10¹⁷ cm^-3 (CVD). The crystallized silicon/graphite interface builds an ohmic contact