Optimized V-shape design of GaN nanodiodes for the generation of Gunn oscillations

Abstract

In this work, recent advances in the design of GaN planar Gunn diodes with asymmetric shape, socalled self-switching diodes, are presented. A particular geometry for the nanodiode is proposed, referred as V-shape, where the width of the channel is intentionally increased as approaching the anode. This design, which reduces the effect of the surface-charges at the anode side, is the most favourable one for the onset of Gunn oscillations, which emerge at lower current levels and with lower threshold voltages as compared to the standard square geometry, thus enhancing the power efficiency of the self-switching diode as sub-millimeter wave emitters

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

“…MC simulations of Gunn oscillations in GaN SSDs including thermal effects show that the heating leads to a decrease of the oscillation frequency due to a lower drift velocity of the Gunn domain. However, even if the temperature increase can be as high as 200 K, the heating is not enough to kill the Gunn oscillations [16][17][18][19][20][21][22][23][24].…”

“…Other issues to be considered when dealing with the Gunn effect in GaN diodes are heating effects [12]. As explained in [16], when the diodes operate under only a DC voltage, the use of a V-shaped design for the channel, instead of the standard square one, allows a decrease in the threshold voltage needed for the onset of Gunn oscillations, which are achieved with a much lower DC current, which helps to alleviate the thermal problems.…”

Time-domain Monte Carlo simulation of GaN planar Gunn nanodiodes in resonant circuits

“…oscillations in GaN SSDs including thermal effects show that the heating leads to a decrease of the oscillation frequency due to a lower drift velocity of the Gunn domain [11], [12].…”

Terahertz harvesting with shape-optimized InAlAs/InGaAs self-switching nanodiodes

“…[1][2][3][4] The novel functionalities that those devices exhibit such as the ability to detect extremely weak signals without applied bias, 5,6 their high sensitivity 7 and their capability to operate in the terahertz regime 5,8 make the SSD concept a rewarding tool that have opened a broad range of applications. 9 In this regard, an area of emerging interest where SSDs find potential applications is energy harvesting of long wave thermal infrared emission emitted by Earth.…”

“…Since the self-switching diodes combine geometrical effects with their electronics transport properties their performance is improved by optimizing their shape. We particularly focus on the referred V-shape asymmetrical channels, 3 and compare their performance with that of the L-shape channels. By using the V-shape geometry the lateral surface-charges are expected to be reduced leading to structures with lower resistance values; typically around some hundreds of kilo-ohms.…”