Deep centers in TiO$_2$-Si structures

The effects of thermal annealing and exposure to oxygen plasma on the electrical and photoelectric properties of metal-TiO$_2$-Si structures are investigated. The TiO$_2$ films are fabricated by the rf magnetron sputtering of a titanium-oxide target onto unheated $n$-Si substrates. The forward and reverse currents of the structures after annealing in argon at 500$^\circ$C are lower than those after annealing at 750$^\circ$C. Exposure of the titanium-dioxide films to oxygen plasma led to a decrease in the currents at all annealing temperatures. It is supposed that the I–V characteristics of the TiO$_2$-Si structures can be described using the model of space-charge-limited currents. The photoelectric characteristics of the samples are investigated via illumination at a wavelength of $\lambda$ = 400 nm. The TiO$_2$-Si structures annealed at 500$^\circ$C without exposure to oxygen plasma exhibit frozen photoconductivity. The relaxation time is 23 $\pm$ 2 min.