Observation of momentum space semi-localization in Si-doped $\beta$-Ga$_2$O$_3$

TL;DR

This study reveals semi-localized electronic states in Si-doped $eta$-Ga$_2$O$_3$, showing momentum space confinement linked to real-space localization, which impacts the material's conduction properties.

Contribution

It provides direct experimental evidence of momentum space semi-localization in Si-doped $eta$-Ga$_2$O$_3$, connecting real-space and momentum-space electronic confinement.

Findings

Observation of non-dispersive states near the Fermi level

Evidence of quantized states with momentum space confinement

Implication of semi-localization in electronic conduction

Abstract

We performed an angle-resolved photoemission spectroscopy study of Si-doped $\beta$-Ga$_2$O$_3$. We observed very small photoemission intensity near the Fermi level corresponding to non-dispersive states assigned to Si impurities. We show evidence for a quantization of these states that is accompanied by a confinement in the momentum space consistent with a real-space finite confinement observed in a previous scanning tunneling microscopy study. Our results suggest that this semi-localization in the conjugate spaces plays a crucial role in the electronic conduction of this material.