Use of AlGaN in the notch region of GaN Gunn diodes

Abstract

The wurtzite gallium nitride (GaN) Gunn diodes with aluminum gallium nitride (AlGaN) as launcher in the notch region are investigated by negative-differential-mobility model based simulation. Under the operation of self-excitation oscillation with dipole domain mode, the simulations show that the diode with two-step-graded AlGaN launcher structure can yield the maximal rf power of 1.95 W and dc/rf conversion efficiency of 1.72% at the fundamental oscillation frequency of around 215 GHz. This kind of Gunn diode structure without the low doping process is convenient for accurately controlling the dopant concentration of GaN epitaxial growth.

Thermal Modeling of the GaN-based Gunn Diode at Terahertz Frequencies

“…As one of the excellent candidates for terahertz radiation source, Gunn diodes have attracted much attention [1][2][3][4][5][6][7][8]. Many recent researches demonstrate that the negative-differential-resistance (NDR) based GaN devices possess outstanding power performance at terahertz frequencies due to its unique electronic properties such as large band gap, high breakdown electric field, high electron drift velocity, and large NDR threshold voltage.…”

“…Many recent researches demonstrate that the negative-differential-resistance (NDR) based GaN devices possess outstanding power performance at terahertz frequencies due to its unique electronic properties such as large band gap, high breakdown electric field, high electron drift velocity, and large NDR threshold voltage. Although theoretical works predict Gunn oscillations in the THz range in GaN diode [4][5][6][7], experimental demonstrations of oscillations have not been achieved due to the technological bottleneck on GaN epitaxial growth and device fabrication. Besides, GaN material would face a serious self-heating problem when it is used for NDR device, because the threshold electric-field for NDR effect is almost 50 times larger than the value of GaAs material.…”

The modulation of multi-domain and harmonic wave in a GaN planar Gunn diode by recess layer

“…The formation of multiple electron domains in a 2DEG channel results in a high degree of nonlinearity in the oscillation waveforms, which enhances the harmonic wave components. Unlike in a traditional vertical Gunn diode, neither a doping junction [16,17] nor a tunneling barrier [18] is needed in the recess-layer planar Gunn diode to provide an electron nucleate site. The selective thinning of the AlGaN layer can be easily realized by the etching process.…”