A study of 2H migration and release in 2H+-irradiated YBa2Cu3O7-δ/LaAlO3 〈100〉 samples during rapid thermal annealing

Abstract

A c-axis oriented YBa2Cu3O7-δ (YBCO) film, ∼ 190 nm thick, deposited onto 〈100〉 LaAlO3 by DC sputtering was irradiated at room temperature with 50-keV 2H+ to a dose of 1 × 1016 ions cm−2. The as-implanted sample was divided into several pieces and annealed in a flowing oxygen ambient using rapid thermal annealing (RTA), at various temperatures between 450 and 900°C. RTA at 450°C for 20 s results in the fast diffusion of 2H out of the film (i.e. the apparent diffusion coefficient is estimated to be larger than 2 × 10−11 cm2/s) but no obvious change is seen in the distribution of 2H in the substrate. All of the trapped 2H in the substrate is found to migrate out the sample after RTA at 900°C for 2 min. After 20 s isochronal RTA at temperatures between 450 and 900°C, the relative release fraction of 2H from the substrate increases near-linearly with increasing anneal temperature. The activation energy (temperature) for 2H release from the weaker traps in the irradiated substrate is estimated to be ∼1.6 eV (500°C). There are stronger traps in the irradiated substrate, with the activation energy (temperature) for 2H release from them being estimated to be larger than 2.3 eV (800°C). The behaviour of implanted 2H during RTA can be explained by the mechanism of 2H detrapping and re-trapping.