EFFECT OF INTERFACES ON THE ELECTRICAL BEHAVIOR OF (PB0.72LA0.28)TIO3 THIN-FILMS

Paraelectric (Pb0.72La0.28)TiO3 or PLT(28) thin films were deposited on platinum coated Si substrates by the sol-gel technique. Two distinct groups of top metals, namely M(T) (Ni, Cr, and Ti, i.e., transition metals) and M(N) (Pt, Au, and Ag, i.e., noble metals) formed Ohmic and Schottky contacts, respectively. A Schottky barrier height of 1.83 eV at the Pt-PLT interface was determined. The conventional Schottky emission and Fowler-Nordheim tunneling equations were modified to account for the voltage dependence of the interfacial permittivity. It was found that Schottky emission, thermionic tunneling, and Fowler-Nordheim tunneling mechanisms were predominant in the voltage ranges of 2<V<7, 7<V<16, and V>16, respectively. (C) 1994 American Institute of Physics.