Epitaxial thin film growth in the U-Ge binary system

TL;DR

This study investigates the growth of uranium-germanium thin films using co-deposition on various substrates, revealing phase stabilization, oxygen effects, and electrical properties of UGe compounds.

Contribution

It demonstrates the stabilization of UGe and UGe$_3$ phases in thin films via sputtering on different substrates, and explores their structural and electrical characteristics.

Findings

Stabilized mixed UGe phases on MgO, CaF$_2$, SrTiO$_3$ substrates.

Observed UO$_2$ formation due to oxygen gettering at high temperatures.

Electrical measurements show residual resistivity ratios up to six.

Abstract

We explore the U-Ge phase diagram using thin film growth by co-deposition of U and Ge via d.c. magnetron sputtering. Using three different single crystal substrates - MgO, CaF$_2$ and SrTiO$_3$ - we have stabilised mixed phase films of mostly UGe$_3$ and UGe, with evidence of UGe$_2$ as well. At higher temperatures UO$_2$ forms as a consequence of gettering of oxygen from several types of substrate. Several UGe$_3$ dominated samples grown on MgO substrates have also been characterised electrically, showing residual resistivity ratios up to six.