Field-effect Self-mixing Terahertz Detectors

A comprehensive device model considering both spatial distributions of the terahertz field and the field-effect self-mixing factor has been constructed for the first time in the thesis. The author has found that it is the strongly localized terahertz field induced in a small fraction of the gated electron channel that plays an important role in the high responsivity. An AlGaN/GaN-based high-electron-mobility transistor with a 2-micron-sized gate and integrated dipole antennas has been developed and can offer a noise-equivalent power as low as 40 pW/Hz1/2 at 900 GHz. By further reducing the gate length down to 0.2 micron, a noise-equivalent power of 6 pW/Hz1/2 has been achieved. This thesis provides detailed experimental techniques and device simulation for revealing the self-mixing mechanism including a scanning probe technique for evaluating the effectiveness of terahertz antennas. As such, the thesis could be served as a valuable introduction towards further development of high-sensitivity field-effect terahertz detectors for practical applications.

Jiandong Sun’s research focuses on exploring terahertz detectors and sources based on low-dimensional plasma wave. In his Ph. D thesis, he developed high-sensitivity terahertz detectors based on the self-mixing effect in gate-controlled two-dimensional electron systems at room temperature. Terahertz antennas and Schottky gates are integrated with the two-dimensional electron gas for manipulating both the localized terahertz field and the field-effect electron channel. The underlying self-mixing properties are uncovered through the transport measurement and simulations. The device model and the characterization techniques he developed in the thesis could be applied for further detector optimization for future real applications.

honors:
1) American Superconductor Corp (AMSC) Award (2012).
2) Nominated by Chinese Academy of Sciences for an outstanding Ph.D. thesis (2013)
3) Honor roll student of Chinese Academy of Sciences (2010)
4) Honor roll student of Chinese Academy of Sciences (2011)

Publications:
[1] J. D. Sun, Y. F. Sun, D. M. Wu, Y. Cai, H. Qin and B. S. Zhang. Highresponsivity, low-noise, room-temperature, self-mixing terahertz detector realized using floating antennas on a GaN-based field-effect transistor, Appl. Phys. Lett. 100, 013506 (2012).
[2] J. D. Sun, H. Qin, R. A. Lewis, Y. F. Sun, X. Y. Zhang, Y. Cai, D. M. Wu, and B. S. Zhang. Probing of localized terahertz self-mixing in a GalGaN field-effect transistor, Appl. Phys. Lett. 100, 173513 (2012).
[3] Y. F. Sun, J. D. Sun, Y. Zhou, R. B. Tan, C. H. Zeng, W. Xue, H. Qin, B. S. Zhang, and D. M. Wu. Room temperature GalGaN self-mixing terahertz detector enhanced by resonant antennas, Appl. Phys. Lett. 98, 252103 (2011).
[4] J. D. Sun, Y. F. Sun, Y. Zhou, Z. P. Zhang, W. K. Lin, C. H. Zen, D. M. Wu, B. S. Zhang, H.Qin. A Terahertz detector Based on GalGaN High Electron Mobility Transistor with Bowtie, AIP Conf. Proc , 1399, 893 (2011); 30th International Conference on the Physics of Semiconductors (ICPS) 2010
[5] R. B. Tan, H. Qin, J. D. Sun, X. Y. Zhang, and B. S. Zhang. Modeling an antenna-coupled graphene field-effect terahertz detector. Appl. Phys. Lett. 103, 173507 (2013)