title: Near-infrared-to-visible highly selective thermal emitters based on an intrinsic semiconductor.
abstract: Control of the thermal emission spectra of emitters will result in improved energy utilization efficiency in a broad range of fields, including lighting, energy harvesting, and sensing. In particular, it is challenging to realize a highly selective thermal emitter in the near-infrared-to-visible range, in which unwanted thermal emission spectral components at longer wavelengths are significantly suppressed, whereas strong emission in the near-infrared-to-visible range is retained. To achieve this, we propose an emitter based on interband transitions in a nanostructured intrinsic semiconductor. The electron thermal fluctuations are first limited to the higher-frequency side of the spectrum, above the semiconductor bandgap, and are then enhanced by the photonic resonance of the structure. Theoretical calculations indicate that optimized intrinsic Si rod-array emitters with a rod radius of 105 nm can convert 59% of the input power into emission of wavelengths shorter than 1100 nm at 1400 K. It is also theoretically indicated that emitters with a rod radius of 190 nm can convert 84% of the input power into emission of <1800-nm wavelength at 1400 K. Experimentally, we fabricated a Si rod-array emitter that exhibited a high peak emissivity of 0.77 at a wavelength of 790 nm and a very low background emissivity of <0.02 to 0.05 at 1100 to 7000 nm, under operation at 1273 K. Use of a nanostructured intrinsic semiconductor that can withstand high temperatures is promising for the development of highly efficient thermal emitters operating in the near-infrared-to-visible range.
authors.affiliation: Department of Electronic Science and Engineering, Kyoto University, Kyoto 615-8510, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Asano
authors.affiliation: Department of Electronic Science and Engineering, Kyoto University, Kyoto 615-8510, Japan.; Energy Technology Laboratories, Osaka Gas Co. Ltd., 6-19-9 Torishima, Konohana-Ku, Osaka 554-0051, Japan.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Suemitsu
authors.affiliation: Department of Electronic Science and Engineering, Kyoto University, Kyoto 615-8510, Japan.
authors.forename: Kohei
authors.initials: K
authors.lastname: Hashimoto
authors.affiliation: Department of Electronic Science and Engineering, Kyoto University, Kyoto 615-8510, Japan.; Hakubi Center, Kyoto University, Yoshida, Kyoto 606-8501, Japan.
authors.forename: Menaka
authors.initials: M
authors.lastname: De Zoysa
authors.affiliation: Department of Electronic Science and Engineering, Kyoto University, Kyoto 615-8510, Japan.
authors.forename: Tatsuya
authors.identifier: 0000-0001-9603-3875
authors.initials: T
authors.lastname: Shibahara
authors.affiliation: Department of Electronic Science and Engineering, Kyoto University, Kyoto 615-8510, Japan.
authors.forename: Tatsunori
authors.initials: T
authors.lastname: Tsutsumi
authors.affiliation: Department of Electronic Science and Engineering, Kyoto University, Kyoto 615-8510, Japan.
authors.forename: Susumu
authors.initials: S
authors.lastname: Noda
keywords: electronic resonance; energy utilization efficiency; interband transition; intrinsic semiconductor; near-infrared; photonic resonance; thermal emission control; thermal emitter; visible