Abstract
The potentials of GaN, SiC, and Si for application as microwave sources in mixed tunnelling avalanche transit time mode operation at submillimetre wave (sub-mm wave) frequency around 0.35 terahertz (THz) are investigated using some computer simulation methods. Design criteria to choose width, doping concentration, and area are highlighted. From the results of our simulation we observed that the Si diode produces the least power output of 41 mW followed by the GaN diode with 760 mW and the SiC diode with 2.89 W. In addition, the GaN diode has more noise than the SiC diode (by 5 dB) as well as the Si diode (by 10 dB). The drastically different performance between the GaN and the SiC diode is attributed to the incorporation of disparate carrier velocity in GaN which were not being used by other authors. In spite of the low power and high noise of the GaN compared to the SiC diode, the presence of several peaks in the mean square noise voltage curves and the existence of several minima in the noise measure curves would open a new direction in the design of GaN low-noise ATT diodes capable of multifrequency tuning like a DAR diode.
Highlights
The potentials of GaN for avalanche transit time (ATT) devices have been explored by several authors [1,2,3]
This can be understood from the fact that Si has a much lower band gap compared to SiC and GaN resulting in higher energy and higher voltage for a breakdown of the latter diodes compared to the former
These features are indicative of superior material performance of GaN. In spite of these facts, the power output [PRF(ωp)] of GaN is much less than that of SiC. The reason for such degradation in power output in GaN diode can be attributed to the disparate carrier velocities leading to lower p-side width and lower voltage drop there
Summary
The potentials of GaN for avalanche transit time (ATT) devices have been explored by several authors [1,2,3] They are based on simulation results of symmetric diode structures where the hole saturation velocity is assumed to be the same as the electron saturation velocity. In report [5], Oguzman et al have calculated the hole saturation velocity using an ensemble Monte Carlo simulator, including the full details of the band structure, and numerically determined phonon scattering rate based on empirical pseudopotential method They found that the average hole energies are significantly lower than the corresponding electron energies believed to be due to the drastic difference in curvature between the uppermost valence bands and the lowest conduction band [5]. The purpose of this paper is to substantiate our earlier work by extending the study and compare the results with those of the industry leader Si and the wide band gap rival SiC for operation as MITATT diodes in the same sub-mm wave band of frequency
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
