Large-signal characterization of GaN-based transistors for accurate nonlinear modelling of dispersive effects

Abstract

A large-signal measurement setup with sinusoidal excitation is used for the characterization of low-frequency dispersive phenomena in III-V FET devices. This low-cost setup operates in the MHz frequency range and its components are easily available in most research laboratories. A dispersive model of the dynamic drain current, taking into account the non linear behaviour of charge trapping phenomena, is identified for an AlGaN/GaN HEMT on the basis of the proposed characterization setup.

New pulsed measurement setup for GaN and GaAs FETs characterization

“…However, it is worth noting that an excessively high duty cycle should be avoided in any case. In fact, this might result in: (1) variations of the thermal state during the pulsed characterization, which is related to the rms value of the voltage waveforms (V rms 2 = δ (1 − δ ) A 2 ); (2) spurious variations of the dynamic drain current due to a second-order dependency of the trap state on the rms values of the applied voltages (mainly observed in GaN transistors [15]). Duty cycles in the order of a few percents are usually adopted.…”

“…This leads to a better understanding of the dispersion mechanism. In fact, the average drain current observed under above-cut-off repetitive pulse voltage excitation can be expressed as [15] where V G 0 and V D 0 are the average gate and drain voltages, is a vector of variables denoting a particular (frozen) state of charged traps, and is the channel temperature corresponding to the power dissipated at the average voltage conditions and at a default base-plate temperature (36°C in our experiments). The frozen state of traps has often been considered a function of the average gate and drain voltages only and this assumption is verified later in this work in the experimental validation section dedicated to GaAs transistor characterization.…”

“…Some authors, e.g. Santarelli et al [15] Jardel et al [16] suggest that the variables might also be dependent on other quantities (such as the rms values of voltages under an almost sinusoidal regime [15] or dependent on the peak values of voltages [16]). This is confirmed in the following section dedicated to GaN transistors.…”

“…Although this kind of characterization seems to work well in association with GaAs technologies, some doubts have been raised recently when considering GaN-based transistors, due to specific properties of the charge trapping dynamics in GaN on SiC devices [15, 16]. Because of this reason, some nonlinear models have been proposed, which avoid the use of pulsed I / V curves, but nevertheless take into account dispersive phenomena (e.g.…”

Non-linear thermal resistance model for the simulation of high power GaN-based devices

“…or both [9,10], is widespread in electrothermal device models and commercial software like ANSYS [11,12]. However, the use of novel technologies based on wide bandgap semiconductors such as GaN, SiC or even diamond, are strongly pushing the limits of the power density that can be managed by practical MMICs.…”