A. I. Il’in, A. A. Ivanov, V. K. Egorov, “Structure, morphology, transport, and mechanism of oxygen loss in YBa$_2$Cu$_3$O$_{7-\delta}$ thin films obtained by pulsed laser deposition with velocity filtration in erosion plume”, Fizika Tverdogo Tela, 2022, Volume 64, Issue 9,Pages 1211

XXVI International Symposium "Nanophysics and Nanoelectronics", Nizhny Novgorod, March 14 - March 17, 2022
Superconductivity

Structure, morphology, transport, and mechanism of oxygen loss in YBa$_2$Cu$_3$O$_{7-\delta}$ thin films obtained by pulsed laser deposition with velocity filtration in erosion plume

A. I. Il’in^a, A. A. Ivanov^b, V. K. Egorov^a

^a Institute of Microelectronics Technology and High-Purity Materials RAS, Chernogolovka, Russia
^b National Engineering Physics Institute "MEPhI", Moscow, Russia

Abstract: We report the study of YBa$_2$Cu$_3$O$_{7-\delta}$ films, synthesized on SrTiO$_3$(100) substrates by pulsed laser deposition with velocity filtration, using X-ray diffractometry, transport measurements, and scanning electron microscopy. We have revealed the dependence of the structure of 100–200 nm thick YBa$_2$Cu$_3$O$_{7-\delta}$ films on deposition time and velocity of particles in erosion plume, set by velocity filter. After deposition, the films, or their part, close to the substrate, consisted of 3–10-nm crystals with oxygen index $\delta$ = 0.08, the same as in the target. For deposition time from 10 to 60 min, we observed the growth of regular pyramids with triangular and quadrangular bases from 20 to 500 nm in size at the base and spiral pyramids with polygonal bases on the film surface. The maximum oxygen loss up to $\delta$ = 0.35 and $T$($R$ = 0) up to 77.4 K coincided with the appearance of spiral pyramids up to 100 nm-high. These findings evidence in favor of oxygen depletion of the top layers of YBa$_2$Cu$_3$O$_{7-\delta}$ thin films through the formation and growth of oxygen-deficient pyramids on their surface. The oxygen index in the range of $\delta$ = 0.08–0.15 in both nanocrystals and regular pyramids of 20–300 nm in size provided $T$($R$ = 0) = 84–87 K and the width of superconducting transition $\Delta T$ = 2.5–3.5 K.

Keywords: pulsed laser deposition, surface morphology, film transport properties, film evolution, SrTiO$_3$.

Received: 29.04.2022
Revised: 29.04.2022
Accepted: 12.05.2022

DOI: 10.21883/FTT.2022.09.52807.26HH