Effects of Electrode Materials and Annealing Ambients on the Electrical Properties of TiO2 Thin Films by Metalorganic Chemical Vapor Deposition

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Abstract
In this work, we investigate the effects of the top electrode materials and annealing ambients on the electrical properties of chemical-vapor-deposited (CVD) TiO2 films. Experimental results indicate that the leakage current is mainly determined by the work function of electrode materials before sintering. The capacitor with TaN top electrode reveals the least leakage. After 450° C and 800° C sintering in N2, owing to its thermal stability, WN is found to be the optimal material for withstanding high-temperature thermal treatment. From the annealing ambient results, N2O was more effective than O2 in reducing leakage current, and furnace annealing in N2O ( FN2O) produces the smallest leakage. Such a phenomenon is primarily owing to the reduction of oxygen vacancies and carbon concentration in TiO2 by the atomic oxygen generated by the dissociation of N2O during the thermal cycle, thereby improving film quality.