Y. Fukuda et al., EFFECTS OF INTERFACIAL ROUGHNESS ON THE LEAKAGE PROPERTIES OF SRTIO3 THIN-FILM CAPACITORS, Integrated ferroelectrics, 11(1-4), 1995, pp. 121-127
Recent reports on the current-voltage (I-V) characteristics of SrTiO3
and (Ba,Sr)TiO3 thin film capacitors with Pt: electrode suggest that t
heir leakage properties are controlled by Schottky emission from catho
de. However, their dynamic permittivities obtained from the Schottky p
lot are always much smaller than those expected from optical measureme
nts. The most plausible approach to explain this disagreement is to in
corporate the effect of electric field enhancement due to interfacial
roughness into the Schottky emission model. Electric field at the inte
rface, for the first order approximation, can be given by [(r+t)/r](V/
t), where r, t and V respectively denote radius of curvature represent
ing interfacial roughness, dielectric thickness and applied voltage. T
his model predicts that I-V characteristics are the functions of r and
V for the ultimate case of r << t. We have closely studied the I-V ch
aracteristics of sputter-deposited SrTiO3 films and have obtained the
results which strongly support our prediction.