Operation of GaN Planar Nanodiodes as THz Detectors and Mixers

Abstract

In this paper, we perform, by means of Monte Carlo simulations and experimental measurements, a geometry optimization of GaN-based nano-diodes for broadband Terahertz direct detection (in terms of responsivity) and mixing (in terms of output power). The capabilities of the so-called self-switching diode (SSD) are analyzed for different dimensions of the channel at room temperature. Signal detection up to the 690 GHz limit of the experimental setup has been achieved at zero bias. The reduction of the channel width increases the detection responsivity, while the reduction in length reduces the responsivity but increases the cutoff frequency. In the case of heterodyne detection an intrinsic bandwidth of at least 100 GHz has been found. The intermediate frequency (IF) power increases for short SSDs, while the optimization in terms of the channel width is a trade-off between a higher non-linearity (obtained for narrow SSDs) and a large current level (obtained for wide SSDs). Moreover, the RF performance can be improved by biasing, with optimum performances reached, as expected, when the DC non-linearity is maximum.

Room Temperature Direct and Heterodyne Detection of 0.28–0.69-THz Waves Based on GaN 2-DEG Unipolar Nanochannels

“…In all cases, the experiments were performed in free-space and room temperature configurations. In order to understand the physical mechanisms and to optimize the performances of the devices for broadband direct detection (in terms of responsivity) and mixing (in terms of output power), a semiclassical MC simulation self-consistently coupled with a Poisson solver is used as previously explained in [13].…”

“…These results are then compared with the intrinsic CL obtained by an MC simulation done on a single nanochannel with L/W = 500/500 nm. Notice that the simulation has been performed for an IF of 50 GHz instead of 1 GHz to decrease the calculation time (and providing the same result, since it is MC IF power is constant below 100 GHz [13]). Fig.…”

“…However, it should also be possible to achieve THz operations with more robust materials, such as GaN. Even if the use of unipolar GaN nanochannels as THz detectors [12] or mixers [13] is fairly new, it presents a lot of room for improvements to make them competitive with a Schottky technology. In a previous paper, through a systematic numerical study based on Monte Carlo (MC) simulations, we have presented the performances of such GaN nanodiodes as direct and heterodyne detectors in the 0.30-THz frequency range [13].…”

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

“…In spite of these efforts, nowadays, the development of compact room temperature, tunable and low-cost powerful THz sources is still a challenge. From our experience in fabricating and characterizing sub-THz devices [22][23][24][25], we have learnt that once a given device potentially exhibiting high frequency oscillations has been fabricated, it is very difficult to experimentally confirm their presence. In some cases, the AC power generated is too small, in others the oscillations take place at too high frequencies, so that their detection becomes difficult.…”

Microwave detection up to 43.5 GHz by GaN nanodiodes: Experimental and analytical responsivity

“…2. Measurements were carried out using a vector network analyzer model PNA X N5244A from Keysight Technologies, in the frequency range between 10 MHz and 43.5 GHz (but the results presented can be extended to the near THz range [5,6]) and a semiconductor characterization system model 4200 SCS from Keithley. The SSDs were contacted using coplanar probes in the groundsignal-ground (GSG) configuration to ensure a good microwave coupling.…”