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.

Comprehensive characterization of Gunn oscillations in In0.53Ga0.47As planar diodes

“…New devices called self-switching diodes have been proposed as promising candidates to exhibit high-frequency GOs in the sub-THz range [16,17]. Focusing the electric field by shaping the profile of nanochannels, they should be able to improve the efficiency of planar Gunn diodes and even help to achieve the challenging fabrication of GaN Gunn diodes [18][19][20][21].…”

Study of InAlAs/InGaAs self-switching diodes for energy harvesting applications

“…The particular symmetry of the I-V curve in the V-shaped geometry results in a Gaussian-like curve of R V , has stimulated investigations in Gunn oscillations-based devices, since it has been demonstrated that this type of electrical oscillations in SSDs could reach submillimeter wavelengths. [21][22][23] Millithaler et al concluded that the V-shaped geometry needs a lower DC current to generate Gunn oscillations, improving the DC-to-AC efficiency and reducing the thermal dissipation issues when compared to L-shaped devices. 22) However, in their design, the diode-like curve is poor due to the large channel width.…”

Analysis of trap states in AlGaN/GaN self-switching diodes via impedance measurements

“…Remarkably, in GaN SSDs, the strategic combination of the SSD geometry with the presence of negative differential mobility, high electrical strength, high saturation velocity and low energy relaxation time, offers an optimal environment for the generation of very high frequency Gunn oscillations [11]. However, in spite of the efforts made in recent years [12,13], no clear experimental evidence of THz oscillations was found so far in GaN manufactured devices. In any case, the good performances of GaN SSDs as detectors of submillimeter-wave signals [14] combined with their planar geometry, which allows for a better free space coupling and a flexibility in the design (for an optimum thermal dissipation and reduction of parasitic effects), enables them to operate not only as detectors but also opens the possibility to develop a completely integrated emitter/detector submillimeter-wave working at room temperature and motivates our study of the behavior of traps in GaN SSDs.…”