Deposition of Silicon Films from Liquid Cyclopentasilane Precursors Using High Pressure Spray System

Si- films were deposited from liquid precursors, especially cyclopentasilane using a high pressure spray deposition system based on an electronically controlled piezo-injector in a inert gas atmosphere. This equipment might be applicable to other liquid precursors and targeted thin Si-films of importance. The thermal properties and reactivity with oxygen of pure liquid cyclopentasilane and its solutions in toluene are investigated by temperature dependent FTIR-Spectroscopy and Differential Scanning Calorimetry. The homogenous films of silicon in µm range thickness are deposited from pure liquid cyclopentasilane and its solutions in toluene on rigid carbon glass plates and on flexible carbon glass fiber substrates using a high pressure spray deposition system. The morphological and structural properties of the silicon films were investigated. These results and the chemical analysis of the films show that the annealed films are homogenous, adhesive and consist of pure polycrystalline silicon. The silicon films deposited from liquid cyclopentasilane in toluene solutions show cracks, whereas silicon films deposited from pure cyclopentasilane are cracks free over at least 400 cm2 and might enable to develop large area solar cells.