Dopant Solubility, and Charge Compensation in La-doped SrSnO3 Films

TL;DR

This study demonstrates high-quality La-doped SrSnO3 films with complete dopant activation, high carrier density, and record mobility, advancing the understanding of doping and transport in perovskite oxide semiconductors.

Contribution

It provides experimental validation of dopant activation and solubility limits in La-doped SrSnO3, and reports record-high mobility in ultra-thin films.

Findings

Carrier density exceeds 1 x 10^20 cm^-3

Record-high mobility of 70 cm^2V^-1s^-1 at room temperature

Complete dopant activation confirmed by spectroscopy and Hall measurements

Abstract

We investigate lanthanum (La) as an n-type dopant in the strain-stabilized tetragonal phase of SrSnO3 grown on GdScO3 (110) using a radical-based hybrid molecular beam epitaxy approach. Fully coherent, epitaxial films with atomically smooth film surface were obtained irrespective of doping density. By combining secondary ion mass spectroscopy and Hall measurements, we demonstrate that each La atom contributes to one electron to the film confirming it occupies Sr-site in SrSnO3 and that it is completely activated. Carrier density exceeding 1 x 10^20 cm-3 was achieved in LSSO films, which is in excellent agreement with the dopant-solubility limit predicted by the density functional theory calculations. A record-high room-temperature mobility of 70 cm2V-1s-1 at 1 x 10^20 cm-3 was obtained in 12 nm La-doped SrSnO3 film making this the thinnest perovskite oxide semiconductor with a reasonably high electron mobility at room temperature. We discuss the structure-dopant-transport property relationships providing essential knowledge for the design of electronic devices using these materials.