Evaluation of Pulsed I–V Analysis as Validation Tool of Nonlinear RF Models of GaN-Based HFETs

Abstract

This paper evaluates the applicability of pulsed I-V measurements as a tool for accurately extracting nonlinear gallium nitride (GaN)-based heterojunction fieldeffect transistor (HFET) models. Two wafers with the identical layer structure but different growth conditions have been investigated. A series of I-V measurements was performed under dc and pulsed conditions demonstrating a dramatic difference in the kink effect and current collapse (knee walkout) suggesting different trapping behaviors. However, when radio frequency (RF) I-V waveform measurements, utilizing active harmonic load-pull, were used to study the impact of these traps on the RF performance, both wafers gave good overall RF performance with no significant difference observed. This absence of correlation between pulsed I-V measurement results and RF performance raises a question about the applicability of pulsed I-V measurements alone as a tool for extracting nonlinear device models in the case of GaN HFETs. Index Terms-Active harmonic load-pull, current collapse, gallium nitride (GaN), heterojunction field-effect transistor (HFET), high-electron mobility transistor, kink effect, knee walkout, pulsed I-V, trapping effect. I. INTRODUCTION D UE to the unique material properties of gallium nitride (GaN), particularly high-electron mobility, high break

Impact of carbon in the buffer on power switching GaN-on-Si and RF GaN-on-SiC HEMTs

“…However the density of Fe and C is rarely reported, and the impact of a known density of C on device performance has only been discussed in Refs. 49,50) where 0.25µm gate length devices were fabricated on two wafers with different C density (the secondary ion mass spectrometrydata for Fe and C are replotted in Fig. 6).…”

“…Here we go beyond that model and include a distributed band-to-band leakage path along the entire gate-drain region 13) . The device geometry was a simple T-gate and corresponds to those used in the experiments of [49][50][51] with LSD 3.75µm, LG 0.25µm.…”

“…Figure 6. SIMS data for Fe and C for the two different growth recipes used to fabricate devices in49,50) .…”

Study of Drain Injected Breakdown Mechanisms in AlGaN/GaN-on-SiC HEMTs

“…1 (b) with kink seen at 3-5 V above the knee. A detailed study on the origin of kink in this wafer, explained using the p-type floating buffer that results from the presence of the relatively high background carbon level in the bulk, can be found in [9][10] and RF measurements in [11].…”

On the performance of GaN‐on‐Silicon, Silicon‐Carbide, and Diamond substrates

“…These acceptor traps play a major role in current collapse and drain lag in pulsed I‐V applications . In addition to that, the acceptor traps are responsible for the anomalous kink effect in the drain current of GaN‐HEMT . The traps could also exist in the surface, which causes the gate‐lag that limits the maximum drain current and reduces the on‐resistance .…”