Layer-by-layer deposition of La1.85Sr0.15CuOx films by pulsed laser ablation

Abstract

Reflection high‐energy electron diffraction (RHEED) has been used to monitor the growth of La_1.85Sr_0.15CuO_x (LSCO) thin films on (100) SrTiO₃ substrates by pulsed laser deposition. The films are grown using a combination of pulsed molecular oxygen and a continuous source of atomic oxygen, with the average background pressure maintained as low as 1 mTorr. The RHEED pattern is sharp and streaky, and the intensity of the specular beam oscillates during the deposition, indicating a two‐dimensional layer‐by‐layer epitaxial growth. The film thickness measured by x‐ray small‐angle interference is consistent with the thickness determined by the RHEED oscillation period with a growth unit of half a unit cell. Thin films of YBa₂Cu₃O_7−δ (YBCO) with good RHEED oscillations have also been grown under similar oxygenation conditions. The low‐pressure‐grown LSCO and YBCO films are superconducting, with zero‐resistance temperatures of 15 and 80 K, respectively.