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Gunn diodes use the Ridley–Watkins–Hilsum effect to generate low noise millimeter wave signals for communication and sensing applications. However, Monte Carlo calculations indicate that the velocity–field characteristics of compensated GaAs contain a second peak due to phonon scattering. A novel device that leverages this double Ridley–Watkins–Hilsum effect to achieve ultra-wideband tunability of low-noise millimeter waves is proposed in this article. The second region of negative differential mobility is gradually introduced in seven mobility profiles, which are each simulated in eight device lengths. It is found that a 2.5 μm Gunn diode with a compensation ratio of 0.6 operating at 160 K has a 700% increase in frequency tunability. An analysis of the domain formation indicates that the increase in tunability is due to significant distortions in domain shape. Gunn diodes with transit lengths of 2 μm and smaller show a 100% increase in tunability due to modulations in the effective transit length and absorption rate. These simulations indicate that compensated GaAs could provide linear, ultra-wideband frequency tunability.

Simulations of conventional Gunn diodes containing the double Gunn effect have shown a significant increase in oscillation frequency and frequency range. However, conventional Gunn diodes suffer from higher phase noise, lower efficiency, and reduced temperature stability due to the lack of a hot electron injector. A study on the performance of a Double Gunn diode with a graded gap injector is presented. The second region of negative differential mobility is gradually introduced in several temperature-dependent mobility models, which are implemented in an energy balance simulation. Devices with transit lengths of 0.7μm, 1.1μm, and 1.65μm are simulated. All devices experience an increase in oscillation frequency with increasing intensities of the double Gunn effect. The frequency range doubles at significant intensities of the effect in the devices with transit lengths of 0.7μm and 1.65μm.