Speaker
Description
Gallium oxide $\beta$-Ga$_2$O$_3$ is currently drawing much attention as a material for high-voltage power devices because of its large band gap ($E_\mathrm{g}\sim$4.9 eV). We investigated the electronic structures of muon as a pseudo-hydrogen in $\beta$-Ga$_2$O$_3$ in which the dilute hydrogen is under the central focus as a crucial factor for the bulk conducting properties. We demonstrate by $\mu$SR study combined with the first principles calculations that muons in $\beta$-Ga$_2$O$_3$ have two electronic structures: a state corresponding to hydrogen that acts as an electron donor (Mu$_1$), bounded to three-coordinated oxygen, and a hydride-like state in rapid motion (Mu$_2$). Furthermore, we imply from the Hall effect measurements that the fractional yield of Mu$_2$ exhibits a close link with the mobility and density of the carriers (electrons).
In the presentation, we will compare our results with those of previous study and discuss the electronic structures of Mu$_1$ and Mu$_2$ in terms of our recently proposed ambipolar model of muon in oxides.
