Oxide thin film diode fabricated by liquid-phase method

A p-type oxide thin film, NiO, and an n-type thin film, ZnO, were fabricated by a liquid phase method using metal acetates as starting reagents. Both the films were transparent, uniform in thickness and porous. By repetition of coating of the n- and p-type films a p-n contact was formed. The contact exhibited nonlinear and rectifying I-V characteristics. A Mott-Schottky plot of the p-n contact revealed that the carrier concentration in each film Tvas constant throughout the thickness and the carrier concentration in NiO was much lower than that estimated fi-om the results obtained using the van der Pauw method. The very low carrier concentration may be due to the existence of interface and surface states in the multilayered porous film.