A simple chemical vapour deposition method for depositing thin TiO2 films

Abstract

Thin films of TiO2 were produced at 130-250°C by chemical vapour deposition (CVD) involving the hydrolysis of TiCl4. An apparatus was developed which gives good control and reproducibility. The reaction takes place on a heated disc that rotates the silicon substrate. Premature reaction between the gases, TiCl4 and water vapour is prevented by appropriate temperature control and careful design of the gas delivery system. With this apparatus the thickness of the TiO2 films is controlled to within ±5% of the target value. Attention is also directed to reducing the pinhole density of the resulting films. The refractive index of the TiO2 films was found to increase with increasing deposition temperature, from 2.1 at around 130°C to 2.4 at 250°C. From capacitance-voltage measurements the surface charge at the TiO2-Si interface of films deposited at 200°C was found to be negative. Hence these TiO2 films are good antireflection coatings for n-type metal/insulator/semiconductor inversionlayer solar cells. © 1983.