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

Abstract

Controlling the emissivity of a thermal emitter has attracted growing interest, with a view toward a new generation of thermal emission devices. To date, all demonstrations have involved using sustained external electric or thermal consumption to maintain a desired emissivity. In the present study, we demonstrated control over the emissivity of a thermal emitter consisting of a film of phase-changing material Ge2Sb2Te5 (GST) on top of a metal film. This thermal emitter achieves broad wavelength-selective spectral emissivity in the mid-infrared. The peak emissivity approaches the ideal blackbody maximum, and a maximum extinction ratio of >10 dB is attainable by switching the 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 toward 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.

Optical constants acquisition and phase change properties of Ge2Sb2Te5 thin films based on spectroscopy

“…Most researchers are interested in Ge 2 Sb 2 Te 5 due to its faster crystallization rate, lower power consumption, as well as the undemanding composition requirements that minor composition deviation does not affect the performance. [14][15][16] Our research focuses on tracking the GST optical constant evolution process during the successive stages of phase-change. As there are coexistence of different proportion of amorphous and crystalline phases at different phase transformation stages.…”

Recent Progress in Active Optical Metasurfaces

“…Du et al recently reported GST–Al bilayer and Cr–GST–Au trilayer structures as wavelength‐tunable mid‐infrared thermal emitters . Importantly, using measured material properties of GST, the authors studied the absorption evolution of the two structures as a function of the degrees of crystallization of GST, which facilitates the continuously tunable emissivity of the proposed devices undergoing different annealing processes.…”

Dynamic Thermal Emission Control Based on Ultrathin Plasmonic Metamaterials Including Phase‐Changing Material GST

“…It is difficult to tune the peak wavelength in such structures, and the emissivity can only be tuned in a limited range from 50% to 80% when the temperature increases from 293 K to 623 K. The thickness of the whole structure is as large as 2 μm (∼0.4λ) in order to suspend top metamaterial pattern above the ground plane. (3) By thermally controlling the phases of phase‐changing materials like Ge2Sb2Te5 (GST) and VOx at different temperatures, tunable thermal emission can be realized based on multilayer structures. The peak wavelength tuning is dependent on the thickness of GST or VOx and the thermal emitters thus present comparatively low design flexibility.…”

“…The ultrathin feature is achieved by adopting the MIM plasmonic metamateirals, in which the emission wavelength can be controlled by the geometric size of top metallic particles without sacrificing the total device thickness. The dynamic low‐power‐consumption control is implemented by incorporating zero‐static‐power phase‐changing material Ge2Sb2Te5 (GST), which has been applied in various energy‐efficient switchable photonic devices . The whole structure shows a total thickness of 550 nm (∼0.023λ), which is well below the subwavelength scale.…”