The self-biased heterojunction effect of ferroelectric thin film on silicon substrate

Several ferroelectric thin films with n-type or p-type conductivity, including undoped and doped lead zirconate titanate, barium titanate, strontium barium niobate, and potassium niobate, as well as lead barium niobate, were made on silicon single-crystal substrates by the sol-gel process. Self-biased heterojunction effects were observed in both p-ferroelectric thin film on n-silicon and n-ferroelectric thin film on p-silicon by the measurement of current-voltage characteristics. It has been observed that either p-n junction or n-p junction in the ferroelectric-semiconductor systems behave like a rectifying diode. However, the junction effect is weak in the p-ferroelectric thin film on p-silicon system. A physical model based on the consideration of energy-band theory has been constructed in explaining this effect. Possible applications of this effect are discussed.