Open Access

ARTICLE

Structural Relaxation and Thermal Robustness of Electron-Beam Evaporated As₂Se₃ Films for Far-Infrared Heterogeneous Metalenses

Weihang Qiu¹, Bo Zhang², Zhaofeng Gu^2,*, Zijun Liu², Xiang Shen², Yimin Chen^1,2,*
1 Department of Microelectronic Science and Engineering, School of Physical Science and Technology, Ningbo University, Ningbo, China
2 Laboratory of Infrared Material and Devices & Key Laboratory of Photoelectric Materials and Devices of Zhejiang Province, Advanced Technology Research Institute, Ningbo University, Ningbo, China
* Corresponding Author: Zhaofeng Gu. Email: ; Yimin Chen. Email:

Chalcogenide Letters https://doi.org/10.32604/cl.2026.089518

Received 21 July 2026; Accepted 26 August 2026; Published online 01 September 2026

Abstract

This study presents electron-beam evaporated As₂Se₃ films tailored for far-infrared heterogeneous metalenses. Characterization via X-ray diffraction and Raman spectroscopy reveals a structurally relaxed network in the films compared to bulk glass, resulting in enhanced infrared transmittance, a reduced refractive index, and a lower glass transition temperature. However, thermal expansion mismatch is found to induce cracking in thick films subjected to thermal cycling. The As₂Se₃/BaF₂ system demonstrates superior adhesion, attributed to a minimal thermal expansion mismatch (Δα < 2.5 × 10⁻⁶°C⁻¹). Notably, an 8 μm thick film endures over thirty rapid heating and liquid nitrogen quenching cycles without degradation, while maintaining a subwavelength thickness and optical properties suitable for metalens design. These findings establish the As₂Se₃/BaF₂ platform as a robust candidate for environmentally stable infrared heterogenous metasurfaces.

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Keywords

Chalcogenide As₂Se₃ film; electron-beam evaporation; infrared metalens; structural relaxation; film adhesion

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