ALD TiO2 thin film as dielectric for Al/p-Si Schottky diode

Electrical analysis of Al/p-Si Schottky diode with titanium dioxide (TiO2) thin film was performed at room temperature. The forward and reverse bias current–voltage (I–V) characteristics of diode were studied. Using thermionic emission (TE) theory, the main electrical parameters of the Al/TiO2/p-Si Schottky diode such as ideality factor (n), zero bias barrier height (ϕ Bo) and series resistance (R s) were estimated from forward bias I–V plots. At the same time, values of n, ϕ Bo and R s were obtained from Cheung’s method. It was shown that electrical parameters obtained from TE theory and Cheung’s method exhibit close agreement with each other. The reverse-bias leakage current mechanism of Al/TiO2/p-Si Schottky barrier diodes was investigated. The I–V curves in the reverse direction are taken and interpreted via both Schottky and Poole–Frenkel effects. Schottky effect was found to be dominant in the reverse direction. In addition, the capacitance–voltage (C–V) and conductance–voltage (G/w–V) characteristics of diode were investigated at different frequencies (50–500 kHz). The frequency dependence of interface states density was obtained from the Hill–Coleman method and the voltage dependence of interface states density was obtained from the high–low frequency capacitance method.