Epitaxial growth and transport properties of Nb-doped SrTiO$_{3}$ thin films

TL;DR

This study reports the successful epitaxial growth of Nb-doped SrTiO$_{3}$ thin films with atomically flat surfaces, exhibiting metallic conductivity and superconductivity at low temperatures, advancing understanding of their transport properties.

Contribution

It demonstrates the growth conditions for high-quality Nb-doped SrTiO$_{3}$ films and characterizes their transport and surface properties, including superconductivity.

Findings

Films show metallic behavior with high residual resistivity ratios.

Atomically flat surfaces with 3.9 Å steps were achieved.

Superconductivity observed at 0.3 K with zero resistance.

Abstract

Nb-doped SrTiO$_{3}$ epitaxial thin films have been prepared on (001) SrTiO$_{3}$ substrates using pulsed laser deposition. A high substrate temperature ($>1000^{\circ}{C}$) was found to be necessary to achieve 2-dimensional growth. Atomic force microscopy reveals atomically flat surfaces with 3.9 \AA $ $ steps. The films show a metallic behavior, residual resistivity ratios between 10 and 100, and low residual resistivity of the order of 10$^{-4}$$\Omega$cm. At 0.3 K, a sharp superconducting transition, reaching zero resistance, is observed.