摘要
Antenna-coupled field-effect-transistors(FETs) offer high sensitivity for terahertz detection. Both the magnitude and the polarity of the response signal are sensitive to the localized terahertz field under the gate. The ability of accurate sensing the intensity pattern is required for terahertz imaging systems. Here, we report artefacts in the intensity pattern of a focused terahertz beam around 1 THz by scanning a silicon-lens and antenna coupled AlGaN/GaN high-electron-mobility-transistor(HEMT) detector. The origin of the image distortion is found to be connected with one of the antenna blocks by probing the localized photocurrents as a function of the beam location and the frequency. Although the exact distortion is found with our specific antenna design, we believe similar artefacts could be commonplace in antenna-coupled FET terahertz detectors when the beam spot becomes comparable with the antenna size. To eliminate such artefacts, new antenna designs are welcomed to achieve strong asymmetry in the terahertz field distribution under the gate while maintaining a more symmetric radiation pattern for the whole antenna.
Antenna-coupled field-effect-transistors(FETs) offer high sensitivity for terahertz detection. Both the magnitude and the polarity of the response signal are sensitive to the localized terahertz field under the gate. The ability of accurate sensing the intensity pattern is required for terahertz imaging systems. Here, we report artefacts in the intensity pattern of a focused terahertz beam around 1 THz by scanning a silicon-lens and antenna coupled AlGaN/GaN high-electron-mobility-transistor(HEMT) detector. The origin of the image distortion is found to be connected with one of the antenna blocks by probing the localized photocurrents as a function of the beam location and the frequency. Although the exact distortion is found with our specific antenna design, we believe similar artefacts could be commonplace in antenna-coupled FET terahertz detectors when the beam spot becomes comparable with the antenna size. To eliminate such artefacts, new antenna designs are welcomed to achieve strong asymmetry in the terahertz field distribution under the gate while maintaining a more symmetric radiation pattern for the whole antenna.
作者
Xiang Li
Jian-Dong Sun
Hong-Juan Huang
Zhi-Peng Zhang
Lin Jin
Yun-Fei Sun
V V Popov
Hua Qin
李想;孙建东;黄宏娟;张志鹏;靳琳;孙云飞;V V Popov;秦华(Key Laboratory of Nanodevices and Applications,Suzhou Institute of Nano-tech and Nano-bionics,Chinese Academy of Sciences,Suzhou 215123,China;School of Nano Technology and Nano Bionics,University of Science and Technology of China,Hefei 230026,China;Nanofabrication Facility of the Suzhou Institute of Nano-tech and Nano-bionics,Chinese Academy of Sciences,Suzhou 215123,China;College of Electronic and Information Engineering,Suzhou University of Sciences and Technology,Suzhou 215009,China;Kotelnikov Institute of Radio Engineering and Electronics,Saratov Branch,Russian Academy of Sciences,Saratov 410019,Russia)
基金
Project supported by the National Key Research and Development Program of China(Grant No.2016YFF0100501)
the National Natural Science Foundation of China(Grant Nos.61771466,61775231,and 61611530708)
the Six Talent Peaks Project of Jiangsu Province,China(Grant No.XXRJ-079)
the Youth Innovation Promotion Association of Chinese Academy of Sciences(Grant No.2017372)
the Russian Foundation for Basic Research(Grant No.17-52-53063)
the Natural Science Foundation of Jiangsu Province,China(Grant No.BK20160400)
