
A well-designed grooved anode contact is adopted to separate the long-channel diode into two short-channel diodes in parallel.

In this paper, a novel gallium nitride (GaN)-based heterostructure Gunn diode is proposed for the first time to enhance the output characteristics of Gunn oscillation waveforms. These results will lay theoretical and experimental foundation for realizing not only milliwatt GaN-based terahertz semiconductor oscillators but also other power devices. The suppress of Gunn oscillation in the device on sapphire is mainly due to the excessive heat generated in the channel that leads to increase of the dead zone and attenuation of electronic domains. Our simulation results show that the best RF output performance comes with the devices on diamond substrate and no oscillating current is observed for devices on sapphire substrate. In this paper, we will, for the first time, systematically investigate the thermal effect on DC IV and output RF characteristics of AlGaN/GaN hetero-structural planar Gunn diodes on different substrates including diamond, SiC, Si and sapphire.

However, high lateral current in the 2DEG channel may lead to failures such as early breakdown and suppression of oscillations. GaN-based planar Gunn diodes are promising terahertz sources for monolithic microwave and terahertz integrated circuits (MMICs and MTICs, respectively) due to high output power and easiness of fabrication and circuit integration.
