Electron paramagnetic resonance signatures of Co2+ and Cu2+ in b-Ga2O3

TL;DR

This study uses electron paramagnetic resonance spectroscopy to identify and analyze the signatures of Co2+ and Cu2+ impurities in b-Ga2O3, revealing their preferred lattice sites and implications for material properties.

Contribution

It provides the first known EPR signatures of Co2+ and Cu2+ in b-Ga2O3 and shows their specific lattice site preferences, aiding in impurity control.

Findings

Identified EPR signatures of Co2+ and Cu2+ in b-Ga2O3

Both ions prefer octahedral gallium lattice sites

Implications for electrical and optical property control

Abstract

Gallium oxide (b-Ga2O3) is a wide-bandgap compound semiconductor with a bandgap of ~ 4.9 eV that is currently considered promising for a wide range of applications ranging from transparent conducting electrodes to UV optoelectronic devices and power electronics. However, all of these applications require a reliable and precise control of electrical and optical properties of the material, which can be largely affected by impurities, such as transition metals commonly present during the growth. In this work we employ electron paramagnetic resonance (EPR) spectroscopy to obtain EPR signatures of the 3d-transition metals Co2+ and Cu2+ in b-Ga2O3 bulk crystals and powders that were unknown so far. Furthermore, we show that Co2+ and Cu2+ both preferentially reside on the octahedral gallium lattice site.