Epitaxial growth of BaTiO3/ZnO heterojunctions and transition from rectification to bipolar resistive switching effect

Epitaxial BaTiO3/ZnO heterojunctions have been grown on a-plane Al2O3 by pulsed laser deposition. The out-of-plane and in-plane epitaxial relationships of BTO/ZnO/Al2O3 are determined to be (100)BTO//(0002)ZnO//(112¯0)Al2O3 and [011]BTO//[21¯1¯0]ZnO//[0001]Al2O3, respectively. A three-domain-epitaxy growth mode was found to coexist in BaTiO3 films, while ZnO was a single domain epitaxially grown on a-Al2O3. A rectification effect was observed for the BTO films grown at high laser energies of 450 and 320 mJ, while bipolar resistive switching was found for those BTO films grown at low laser energies of 280 and 200 mJ. The transition from the rectification effect to the bipolar resistive switching effect can be understood by the variance of interface state density.