Scalable, Simple, and Versatile Encapsulation of 2D Materials and Devices

Abstract

Air-sensitive 2D materials present a fundamental challenge for device integration. Encapsulation is often required to preserve intrinsic properties, yet conventional protection strategies often fail for thicker layers and complicate fabrication. Here, we demonstrate that electron-beam (e-beam) evaporated aluminum oxide (${\mathrm{AlO}}_x$) serves as both an effective encapsulation layer and a platform for direct device fabrication. Unlike transfer-based approaches, this scalable method is compatible with thicker flakes and full device or wafer coverage. It requires no stacking procedures and enables contacts without post-encapsulation etching. Using rare-earth tritellurides (${\mathrm{RTe}}_3$, R = La, Er), semimetallic ${\mathrm{WTe}}_2$, and superconducting ${\mathrm{FeTe}}_x{\mathrm{Se}}_{1-x}$, we show that ${\mathrm{AlO}}_x$ suppresses oxidation and preserves intrinsic optical and electronic properties. We establish substrate-dependent optimization of encapsulation across a range of flake thicknesses, demonstrate that ultrathin ${\mathrm{AlO}}_x$ preserves ${\mathrm{WTe}}_2$'s plasmonic response and maintains superconducting performance in ${\mathrm{FeTe}}_x{\mathrm{Se}}_{1-x}$. Thus we overcome the longstanding tradeoff between encapsulation and straightforward device fabrication in fragile quantum materials.