Effects of lattice strains on the interfacial potential in La0.67Ca0.33MnO3/SrTiO3:Nb heterojunctions

Oxide p-n heterojunctions composed of La0.67Ca0.33MnO3 (LCMO) films with different thickness and SrTiO3:Nb 0.1 wt % are fabricated and the effects of thickness on the interfacial potential are experimentally studied. Excellent rectifying behavior of the junctions well described by the Shockley equation is observed and the interfacial potential eVD is obtained for all of the junctions based on an analysis of the current-voltage characteristics. The remarkable result of the present work is the strong dependence of the interfacial potential on the thickness of LCMO films: eVD increases from 0.5 to 0.72 eV as the thickness increase from 3.6 to 33 nm. The strain in the LCMO film, which affects the carrier density through modulating the Jahn–Teller effect, is believed to be responsible for the observation.