Graphene hot-electron light bulb: incandescence from hBN-encapsulated graphene in air

TL;DR

This paper demonstrates that hBN-encapsulated graphene can sustain high-temperature incandescence in air, enabling stable, high-temperature optoelectronic applications by preventing oxidation and modifying emission spectra.

Contribution

It introduces hBN encapsulation for graphene, allowing high-temperature incandescence in ambient conditions and spectral tuning via a photonic cavity.

Findings

Graphene can be heated to over 2000 K in air without oxidation.

hBN encapsulation provides excellent protection and stability.

Thermal emission can be shifted to visible spectrum using a cavity.

Abstract

The excellent electronic and mechanical properties of graphene allow it to sustain very large currents, enabling its incandescence through Joule heating in suspended devices. Although interesting scientifically and promising technologically, this process is unattainable in ambient environment, because graphene quickly oxidises at high temperatures. Here, we take the performance of graphene-based incandescent devices to the next level by encapsulating graphene with hexagonal boron nitride (hBN). Remarkably, we found that the hBN encapsulation provides an excellent protection for hot graphene filaments even at temperatures well above 2000 K. Unrivalled oxidation resistance of hBN combined with atomically clean graphene/hBN interface allows for a stable light emission from our devices in atmosphere for many hours of continuous operation. Furthermore, when confined in a simple photonic cavity, the thermal emission spectrum is modified by a cavity mode, shifting the emission to the visible range spectrum. We believe our results demonstrate that hBN/graphene heterostructures can be used to conveniently explore the technologically important high-temperature regime and to pave the way for future optoelectronic applications of graphene-based systems.