Strong bulk-surface interaction dominated in-plane anisotropy of electronic structure in GaTe

TL;DR

This study uses advanced spectroscopy and calculations to reveal that bulk-surface interactions, rather than geometric factors, dominate the in-plane electronic anisotropy in GaTe, with implications for nanoelectronics.

Contribution

It demonstrates that strong bulk-surface interactions, not geometric effects, govern the in-plane anisotropy in GaTe's electronic structure, supported by experimental and theoretical analysis.

Findings

Bulk-surface interaction dominates in-plane anisotropy.

Thickness-dependent band gap transitions occur in GaTe.

In-plane hole effective mass anisotropy is reversed with layer increase.

Abstract

Recently, intriguing physical properties have been unraveled in anisotropic layered semiconductors, in which the in-plane electronic band structure anisotropy often originates from the low crystallographic symmetry and thus a thickness-independent character emerges. Here, we apply high-resolution angle-resolved photoemission spectroscopy to directly image the in-plane anisotropic energy bands in monoclinic gallium telluride (GaTe). Our first-principles calculations reveal the in-plane anisotropic energy band structure of GaTe measured experimentally is dominated by a strong bulk-surface interaction rather than geometric factors, surface effect and quantum confinement effect. Furthermore, accompanied by the thickness of GaTe increasing from mono- to few-layers, the strong interlayer coupling of GaTe induces direct-indirect-direct band gap transitions and the in-plane anisotropy of hole effective mass is reversed. Our results shed light on the physical origins of in-plane anisotropy of electronic structure in GaTe, paving the way for the design and device applications of nanoelectronics and optoelectronics based on anisotropic layered semiconductors.