P.G. Li

Influence of oxygen vacancy on resistive switching property of Ag/Nb:SrTiO3/Ti structure

Abstract With the aim to get optimised resistive switching properties, the influence of oxygen vacancy concentration of Nb:SrTiO3 (NSTO) on the resistive switching properties of Ag/NSTO/Ti structure was studied. To obtain the NSTO with different oxygen vacancy concentrations, the substrates had been annealed in different atmospheres and temperatures before they were used to fabricate Ag/NSTO/Ti structure. The resistive switching properties were investigated by measuring I–V characteristics, endurance ability and resistance distribution at room temperature. The results show that both annealing in oxygen atmosphere and vacuum atmosphere degraded the switching properties. In our case, the device annealed in air at 700°C displayed the best resistive switching behaviour. After analysis, we suggest that both Schottky barrier height and barrier width, which can be tuned by changing the oxygen vacancy concentration, play important roles in getting high quality resistive switching property.

Tunnelling current in YBa2Cu3O7−δ/Nb-doped SrTiO3 heterojunctions

We report the fabrication of YBa2Cu3O7−δ/Nb-doped (0.8 wt%) SrTiO3 p–n junctions by pulsed electron deposition, photolithography and Ar-ion etching techniques. In the junctions, the abnormal rectifying behaviour and the Esaki tunnelling diode-like characteristic have been observed above and below the superconducting transition temperature TC of YBa2Cu3O7−δ, respectively. The tunnelling process is responsible for these behaviours and the depletion layer formed at the junction interface with very low resistance is the dominating factor. The intriguing properties in this work indicate that it is possible to realize the functions of traditional semiconductor diodes by using high-temperature superconductor-based heterojunctions.