Surpassing the limits: Is it possible to achieve high-purity SrRuO3 thin films using PLD?

Attaining high residual resistivity ratio (RRR) values in SrRuO3 (SRO) thin films is a critical goal for enhancing their electronic properties, particularly for applications in oxide electronics. However, ruthenates are very sensitive to defects. The main techniques for the growth of SRO thin films are Molecular Beam Epitaxy (MBE) and Pulsed Laser Deposition (PLD). While MBE has successfully produced SRO films with RRR values close to triple digits (with recent reports showing SRO on DyScO3(110) with RRR above 200) [1,2], PLD thin films have struggled to surpass single-digit values, with only a single report of RRR of 14.1 for the SRO/NdGaO3(110) system [3]. Despite the advantage of growing films with consistent quality, the conditions within the plume make SRO films grown by PLD inherently Ru-poor [4]. This research systematically investigates the growth conditions of SRO films on TiO2-terminated SrTiO3 (STO) substrates using PLD, focusing on optimizing parameters to achieve higher RRR values.

For this study, SRO thin films were deposited via PLD, with adjustments made to deposition temperature, oxygen partial pressure, and substrate orientation. The films' crystallinity was assessed using X-ray diffraction (XRD), while their electrical properties, particularly resistivity, were measured to determine overall quality and purity. Although high crystallinity alone did not ensure higher film quality, certain conditions showed promise in achieving double-digit RRR values. Notably, films grown on SrTiO3(111) achieved an RRR of 10.4, as illustrated by the resistivity plot in Figure 1. Through systematic growth studies, this research highlights the potential to overcome PLD's traditional limitations in producing high-quality SRO films. By identifying the critical factors that influence film quality, our findings provide a pathway for further optimization and potential breakthroughs in the fabrication of SRO thin films for advanced electronic applications.