Tune turn-on voltage of LaFeO_3−x/Nb:SrTiO₃p-n junctions by oxygen vacancy

Oxide semiconductors with high expectations are regarded as the best candidate in the next generation thin film transistors. Flexible structure endows perovskite oxide semiconductors with the potential to satisfy different application requirements. In this letter, LaFeO 3 epi-films (epitaxial films) were deposited on Nd-SrTiO 3 to construct p-n junctions. The junctions show distinct rectification characteristic with a high rectification ratio of ~5 × 10 3 at ±2 V. Through annealing in deficient oxygen ambience, changes in LaFeO 3 structure by introducing oxygen vacancies lead to the different turn-on voltages. Confirmed by XPS data, oxygen vacancies result in the slight reduction of Fe 3+ to Fe 2+ and the increase in holes concentration. Simultaneously, the location of Fermi Level shifts toward the top of valance band and barrier height for carriers increases gradually. Correspondingly, the turn-on voltage increases as lowering anneal oxygen pressure.