Cr2O3 thin films grown at room temperature by low pressure laser chemical vapour deposition

Chromia (Cr₂O₃) has been extensively explored for the purpose of developing widespread industrial applications, owing to the convergence of a variety of mechanical, physical and chemical properties in one single oxide material. Various methods have been used for large area synthesis of Cr₂O₃ films. However, for selective area growth and growth on thermally sensitive materials, laser-assisted chemical vapour deposition (LCVD) can be applied advantageously.Here we report on the growth of single layers of pure Cr₂O₃ onto sapphire substrates at room temperature by low pressure photolytic LCVD, using UV laser radiation and Cr(CO)₆ as chromium precursor. The feasibility of the LCVD technique to access selective area deposition of chromia thin films is demonstrated. Best results were obtained for a laser fluence of 120 mJ cm⁻² and a partial pressure ratio of O₂ to Cr(CO)₆ of 1.0. Samples grown with these experimental parameters are polycrystalline and their microstructure is characterised by a high density of particles whose size follows a lognormal distribution. Deposition rates of 0.1 nm s⁻¹ and mean particle sizes of 1.85 μm were measured for these films.