Blackbody-like infrared radiation in stacked graphene P–N junction diode

Abstract

The electrical and optical properties of a stacked graphene p–n junction were investigated. N-type and p-type graphene films epitaxially grown on a SiC substrate were directly bonded to each other in a face-to-face manner. The current–voltage characteristics of the graphene junction diode exhibited an Ohmic behavior below 20 V. The conductance increased in the bias range above 20 V and had a peak around 65 V. The emission spectrum and temperature of the graphene p–n junction were measured using Fourier-transform far-infrared (FTIR) spectroscopy and infrared bolometer array. An electrically induced blackbody-like radiation with a peak wavelength of 10.2 μm was observed. Although the temperature change estimated using the bolometer results was 66 K at a power of 1.2 W, the peak wavelength of the FTIR spectrum was constant. An electrically induced blackbody-like far-infrared emission diode with a defined peak wavelength was successfully realized using the stacked graphene p–n junctions.

Infrared Radiation of Graphene Electrothermal Film Triggered Alpha and Theta Brainwaves

“…Under a bias voltage of 5 V, a temperature of 40 to 60 °C can be achieved under the feedback of NTC thermistor in the graphene film, as shown in Figure 2e. Broad infrared radiation can be detected at wavelengths between 4 and 20 μm, [ 14,15 ] which can penetrate 2–3 mm into human skin through the scalp, [ 16 ] as shown in Figure 2f. Especially, the peak energy of the infrared radiation spectrum of graphene film covers the human‐body thermal‐radiation wavelength range from 7 to 14 μm, with radiation energy accounted for more than 50% as shown in the shaded area of Figure 2f, so the infrared radiation from the graphene film can be effectively absorbed by the human skin.…”

“…[ 13 ] While passing a current through the graphene, mid‐infrared and far‐infrared rays (4–20 μm) are radiated into free space. [ 14 ] Recently, we have demonstrated the fabrication of large‐scale multilayer graphene and patented it as the multilayer graphene film with a high far‐infrared emissivity over 90%, [ 15 ] which can penetrate 2–3 mm into human skin. [ 16 ] Especially, the infrared radiation of graphene is matching with the human radiation wavelength (7–14 μm), [ 17 ] which can substantially exert strong rotational and vibrational effects with humans at the molecular level.…”

Far-infrared emission from graphene on SiC by current injection

“…Recently, stacked graphene P-N junction diodes constructed using large-area (100 mm 2 ) graphene on SiC were developed with a high emission efficiency of 10%. 25) Blackbody-like emission with constant peak wavelength (10.2 μm), regardless of the electrical power, based on a non-thermal mechanism was also reported. Exploring the fundamental physics of far-infrared emission from the biased graphene is critical for the establishment of a new platform for developing high-power, high-efficiency infrared emitters.…”

“…3(a). 25) Radiant exitance E, 28) formerly called radiant emittance, 29) which is the energy density of an ideal blackbody, is expressed using α, P [W], emissivity, ε, and radiation area, S [m 2 ], as follows:…”

Resistive-switching behavior in stacked graphene diode

“…[19][20][21] Recently, N. Murakami et al reported nonlinear I-V characteristics in stacked graphene far-infrared emitter. 22) However, the nonlinear electrical properties were not discussed in detail. Because graphene is a semi-metal, a switching device with high on-off ratio has not been established.…”