【Research and Development of China Instrument Network Instrumentation” Qinhua Team, Suzhou Nanotechnology and Nanobionics Institute, Chinese Academy of Sciences, Key Laboratory of Nanodevices and Applications, Chinese Academy of Sciences and National Key Laboratory of Application Specific Integrated Circuit, Institute of Electronics, China Electronics Technology Group Co., Ltd. In cooperation, a high-sensitivity graphene terahertz detector was successfully obtained, and the sensitivity reached the best level of the same type of graphene detector. The result was recently published in the carbon magazine Carbon (116, 760-765 (2017)).


Terahertz wave is an electromagnetic wave with a frequency between infrared and millimeter waves. It has important application prospects in fields such as information, biomedicine and environmental detection. However, the development of terahertz technology has been subject to the bottleneck of the shortage of small high power light sources and room temperature high sensitivity detectors. At present, the light source and detector technology have been greatly improved, and terahertz imaging technology is gradually entering the hazardous chemicals spectrum detection, bioimaging, and human security applications, but in the 0.3-3.0 THz core "terahertz space" high Power luminescence and high sensitivity detection are still technical problems. For example, a solid-state terahertz source operating at room temperature, emitting at frequencies above 0.3 THz, and outputting power in the order of 1-100 milliwatts is still in development. For another example, the remote real-time passive THz human body security requires the detector's noise equivalent power (NEP) to be in the order of 10 -15 W/Hz 1/2, and currently only superconducting detectors operating at cryogenic temperatures can approach. This sensitivity. Therefore, the development of ultra-high sensitivity terahertz detectors working at room temperature is of great significance for advancing terahertz technology applications.

The Suzhou Nanometer Institute team has been devoted to the study of ultrahigh-sensitivity terahertz detectors at room temperature. The development of new two-dimensional electron gas (2DEG) based on conventional semiconductor heterojunctions such as AlGaN/GaN and graphene Hertz Mixing detector. Dirac two-dimensional electron materials such as graphene provide high electron mobility, broadband optical absorption, highly tunable Fermi levels, bipolar carriers, and their nonlinear transport properties for efficient mixing detection.

The progress was achieved through the cooperation of two key laboratories, which leveraged the advantages of high-quality double-layer graphene epitaxially grown on silicon carbide (SiC) substrates, high-efficiency dipole antennas and detector designs, and self-aligned antenna grid processes. Self-mixing/Homodyne mixing detector with a 0.34 THz frequency band has a voltage response of 30 V/W, which reduces the detector impedance to 203 Ω or less (detector thermal noise voltage is less than the reading The voltage noise of the circuit is measured. The measured noise equivalent power is about 163 pW/Hz1/2 (the equivalent noise power limited by thermal noise is only 51 pW/Hz1/2). Based on this detector a clear perspective imaging of fresh leaves is achieved. At present, the joint team has further implemented graphene heteromixing and sub-harmonic mixing with a maximum detection frequency of 0.65 THz.

This cooperation broke through the previous equivalent noise power (~207,000 pW/Hz1/2) of the CVD-grown graphene-based detector obtained by the Suzhou Nanometer Institute team (Chin. Phys. B 24, 047206 (2015)). The level of detection sensitivity predicted in 2013 (Appl. Phys. Lett. 103, 173507 (2013)). The research results show that the sensitivity of graphene detector can be further improved by 2-3 orders of magnitude, but the formation of its practical technology still needs to further breakthrough the key technologies such as design and manufacturing.

The development of the terahertz detector has received strong support from the National Natural Science Foundation of China (No. 61271157, 61401456, 61306006), the Nano Processing Institute of the Chinese Academy of Sciences, the test and analysis platform, and the Institute of Superconductivity of Nanjing University.

(Original title: Suzhou Nano Institute made progress in the research of high sensitivity graphene terahertz detectors)

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