Monte Carlo study of the operation of GaN planar nanodiodes as sub-THz emitters in resonant circuits

Abstract

A study of the high-frequency performance of GaN-based asymmetric self-switching diodes (SSDs) designed for a room-temperature sub-THz Gunn emission, and connected to a resonant RLC parallel circuit, is reported. With the aim of facilitating the achievement and control of Gunn oscillations, which can potentially allow the emission of THz radiation by GaN SSDs, a time-domain Monte Carlo (MC) theoretical study is provided. The simulator has been validated by comparison with the I–V curves of similar fabricated structures, including the possibility of heating effects. A V-shaped SSD has been found to be more efficient than the square one in terms of the DC to AC conversion efficiency η. Indeed, according to our MC results, a value of η of at least 0.35% @ 270 GHz can be achieved for the V-shaped SSD at room temperature by using an adequate resonant circuit. This value can be increased up to 0.80%, even when considering the heating effects, with appropriate RLC elements. Furthermore, simulations show that when several diodes are fabricated in parallel in order to enhance the emitted power, there is no synchronization between the oscillations of all the SSDs; however, the phase-shift effects can be solved using a synchronized current injection by the attachment of a resonant circuit.