Terahertz emission from plasma waves in GaN field effect transistors

• Applicants: Professor Dr.-Ing. Wolfgang Heinrich; Professor Dr. Hartmut G. Roskos, since 7/2013
• Subject Area: Electronic Semiconductors, Components and Circuits, Integrated Systems, Sensor Technology, Theoretical Electrical Engineering ; Experimental Condensed Matter Physics
• Term: from 2012 to 2016
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 227991129

• Final Report Year: 2016

Final Report Abstract

Emission according to plasmon phenomena in the THz range as predicted by Dyakonov and Shur (1993) has not been observed for any of the dedicated structures with small transistors and antennas, which yield best performance in the detector case. Rather, a plasmonic-like emission pattern was obtained for multi-finger transistors with large gate width (8 finger with 125µm width each, finger pitch oft 50 µm) without any special antenna, which are standard for microwave applications. The radiation is observed through the substrate. This emission increases with the bias drain-source current when the gate bias is varied. It scales with total gate width and hence is observed best for large transistors. Experiments at pulsed operation reveal a decrease of the emission amplitude which is nearly proportional to 1/f at frequencies for all modulation frequencies above 10 Hz. Further investigations yield time constants in the range 20…50 ms. This can be explained only by thermal or trap effects, of which traps appear to be more likely the reason. Summarizing, one can state that the measured emission effects are very similar to those observed by others. However, a closer analysis shows that they are not in line with the conventional Dyakonov-Shur theory. Regarding applications, one should note that the time constants in the ms range are far from what is needed for communication systems.

Publications

• “Bow-tie-antenna-coupled terahertz detectors using AlGaN/GaN field-effect transistors with 0.25 micrometer gate length,” in Proc. 2013 European Microwave Integrated Circuits Conference (EuMIC), 2013, pp. 212–215
  M. Bauer, A. Lisauskas, S. Boppel, M. Mundt, V. Krozer, H. G. Roskos, S. Chevtchenko, J. Würfl, W. Heinrich, and G. Trankle
  
• “High-Sensitivity Wideband THz Detectors Based on GaN HEMTs with Integrated Bow-Tie Antennas,” in Proc. 2015 European Microwave Integrated Circuits Conf. (EuMiC), 2015, pp. 1-4
  M. Bauer, A. Rämer, S. Boppel, S. Chevtchenko, A. Lisauskas, W. Heinrich, V. Krozer and H.G. Roskos
  (See online at https://doi.org/10.1109/EuMIC.2015.7345053)
• “Terahertz rectification by plasmons and hot carriers in gated 2D electron gases,” in proceedings of the International Conference on Noise and Fluctuations (ICNF) 2015, pp. 1–5
  A. Lisauskas, M. Bauer, A. Ramer, K. Ikamas, J. Matukas, S. Chevtchenko, W. Heinrich, V. Krozer, and H. G. Roskos
  (See online at https://doi.org/10.1109/ICNF.2015.7288628)
• “0.25-um GaN TeraFETs Optimized as THz Power Detectors and Intensity-Gradient Sensors,” IEEE Transactions on Terahertz Science and Technology, vol. 6, no. 2, pp. 348 – 350, 2016
  S. Boppel, M. Ragauskas, A. Hajo, M. Bauer, A. Lisauskas, S. Chevtchenko, A. Ramer, I. Kasalynas, G. Valusis, H.-J. Wurfl, W. Heinrich, G. Trankle, V. Krozer, and H. G. Roskos
  (See online at https://doi.org/10.1109/TTHZ.2016.2520202)