Control over emissivity of zero-static-power thermal emitters based on phase changing material GST

TL;DR

This paper demonstrates a novel thermal emitter using phase-changing GST material that can switch and tune emissivity in the mid-infrared without continuous external power, enabling advanced thermal control applications.

Contribution

It introduces a GST-based thermal emitter with switchable and tunable emissivity, achieving high extinction ratios and broad spectral control without sustained external energy input.

Findings

Peak emissivity approaches blackbody maximum

Achieves over 10dB extinction ratio

Emissivity can be continuously tuned via intermediate phases

Abstract

Controlling the emissivity of a thermal emitter has attracted growing interest with a view towards a new generation of thermal emission devices. So far, all demonstrations have involved sustained external electric or thermal consumption to maintain a desired emissivity. Here control over the emissivity of a thermal emitter consisting of a phase changing material Ge2Sb2Te5 (GST) film on top of a metal film is demonstrated. This thermal emitter shows broad wavelength-selective spectral emissivity in the mid-infrared. The peak emissivity approaches the ideal blackbody maximum and a maximum extinction ratio of above 10dB is attainable by switching GST between the crystalline and amorphous phases. By controlling the intermediate phases, the emissivity can be continuously tuned. This switchable, tunable, wavelength-selective and thermally stable thermal emitter will pave the way towards the ultimate control of thermal emissivity in the field of fundamental science as well as for energy-harvesting and thermal control applications, including thermophotovoltaics, light sources, infrared imaging and radiative coolers.