Transport properties of sol–gel derived La0.8Ba0.2MnO3/Nd:SrTiO3 heterojunctions

Heterojunctions with excellent rectifying properties are formed by growing La0.8Ba0.2MnO3 films on Nd doped SrTiO3 single crystal substrate via sol–gel method. Detailed studies show that at low temperatures tunneling effect dominates the transport process across the junction both for forward and reverse bias. While at high temperatures, thermionic emission and Frenkel–Poole emission dominate at forward and reverse bias, respectively. The most striking result here is the appearance of metal–insulator transition when the junction is reverse-biased, and the transition temperature increases by 18 K when the reverse bias voltage increases from −0.9 V to −2.0 V. This phenomenon is explained by the strong electric field effect on the physical properties of the space charge zone.