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Smita Francis *, and Robert van Zyl
Cape Peninsula University of Technology, French South African Institute of Technology, Department of Electrical, Electronic and Computer Engineering, Symphony Way, Bellville, 7535, South Africa.
* Email: sfrancis@polytechnic.edu.na
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Abstract: The microwave performance of a two domain GaN Gunn diode is investigated at a fundamental frequency of 0.175 THz and its second and third harmonics through Monte Carlo particle simulations. Simulation results show that the two domain diode is feasible and that a significant increase in output power is achieved compared to that of a single domain diode. Furthermore, the microwave performance of the two domain diode can be enhanced by appropriate engineering of the transit region doping profiles. Three doping profiles are considered, namely nominally flat, exponentially increasing and exponentially decreasing, towards the anode contact regions. The exponentially increasing doping profile yields the highest output power, with 5 W, 514 mW and 87 mW generated at 0.175 THz, 0.350 THz and 0.525 THz, respectively. Thermal heating is generally significant in Gunn diode operation, but especially so for GaN diodes. Hence, thermal modeling is incorporated in the simulations consistently with the dynamic evolution of electrons through the device.
This investigation concludes that a narrow pulsed bias voltage is preferred in the simulation of the GaN Gunn diodes to overcome the adverse effect of thermal heating. It is reported that the narrow pulsed bias voltage enhances the performance of the two domain diode. Under these conditions the two domain GaN Gunn diode exhibits a maximum operational frequency limit of 0.525 THz.
Keywords: Gunn diode, Graded transit region, Negative differential resistance, Multi domain, Monte Carlo simulation.
Received: 2014-10-02
Published: 2015-3-31
Cite this article:
Smita Francis, and Robert van Zyl. Evaluating the microwave performance of a two domain GaN Gunn diode for THz applications[J]. International Journal of Terahertz Science and Technology, 2015, Vol.8, No.1: 25-34. DOI:10.11906/TST.025-034.2015.03.03
URL: http://www.tstnetwork.org/10.11906/TST.025-034.2015.03.03
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