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Journal ArticleDOI

Transient stress characterization of AlGaN/GaN HEMTs due to electrical and thermal effects

TL;DR: Finite element simulation results of the transient stress response of an AlGaN/GaN high electron mobility transistor (HEMT) suggest transient failure mechanisms may differ from those previously studied under DC operation due to large amount of cyclic loading of a device around the gate structure.
About: This article is published in Microelectronics Reliability.The article was published on 2015-12-01 and is currently open access. It has received 34 citations till now. The article focuses on the topics: Stress (mechanics) & High-electron-mobility transistor.
Citations
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Journal ArticleDOI
TL;DR: In this article, gate resistance thermometry (GRT) was used to determine the channel temperature of AlGaN/GaN high electron-mobility transistors under various bias conditions.
Abstract: In this paper, gate resistance thermometry (GRT) was used to determine the channel temperature of AlGaN/GaN high electron-mobility transistors. Raman thermometry has been used to verify GRT by comparing the channel temperatures measured by both techniques under various bias conditions. To further validate this technique, a thermal finite-element model has been developed to model the heat dissipation throughout the devices. Comparisons show that the GRT method averages the temperature over the gate width, yielding a slightly lower peak temperature than Raman thermography. Overall, this method provides a fast and simple technique to determine the average temperature under both steady-state and pulsed bias conditions.

40 citations


Cites background from "Transient stress characterization o..."

  • ...Joule heating mostly occurring in the depletion region and requires the need for electrothermal simulations [16]....

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Journal ArticleDOI
TL;DR: In this paper, the authors studied the self-heating mechanism and its impact on electrical performance of short gate length GaN high electron mobility transistors (HEMTs) based on electrothermal TCAD simulations.
Abstract: In this paper, we study the self-heating mechanism and its impact on electrical performance of short gate length GaN high electron mobility transistors (HEMTs) based on electrothermal TCAD simulations. We propose an equivalent channel temperature to quantify the current degradation due to self-heating and also resolve the discrepancies between temperature measurements through electrical methods and thermal methods in the literature. We then explain the equivalent channel temperature’s behavior using the temperature- and field-dependent electron transport theory for short gate length HEMTs. The implications and guidelines to the various aspects of device design are also discussed.

39 citations


Cites background from "Transient stress characterization o..."

  • ...Therefore, both the top surface and the two sidewalls are assumed adiabatic [28]....

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Journal ArticleDOI
TL;DR: In this article, the authors used transient thermoreflectance imaging (TTI) to measure the temperature rise of the passivated gate metal measured by TTI and the averaged gate temperature monitored by gate resistance thermometry (GRT).
Abstract: The development of steady-state thermal characterization techniques for AlGaN/GaN high-electron mobility transistors (HEMTs) has been used to measure the device’s peak temperature under DC conditions. Despite these methods enabling the accurate quantification of the device’s effective thermal resistance and power density dependence, transient thermometry techniques are necessary to understand the nanoscale thermal transport within the active GaN layer where the highly localized joule heating occurs. One technique that has shown the ability to achieve this is transient thermoreflectance imaging (TTI). The accuracy of TTI is based on using the correct thermoreflectance coefficient. In the past, alternative techniques have been used to adjust the thermoreflectance coefficient to match the correct temperature rise in the device. This paper provides a new method to accurately determine the thermoreflectance coefficient of a given surface and is validated via an electrical method: gate resistance thermometry (GRT). Close agreement is shown between the temperature rise of the passivated gate metal measured by TTI and the averaged gate temperature monitored by GRT. Overall, TTI can now be used to thermally map GaN HEMTs under pulsed conditions providing simultaneously a submicrosecond temporal resolution and a submicrometer spatial resolution.

38 citations


Additional excerpts

  • ...transiently powered GaN HEMTs is complex [13]....

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01 Jan 2011
TL;DR: In this article, a physics-based finite element model of operation of an AlGaN/GaN HEMT with device geometry inputs taken from transmission electron microscope cross sections and calibrated by comparison with measured electrical data comprising standard field-effect transistor metrics and less well-known model parameters is presented.
Abstract: : We present a physics-based finite-element model of operation of an AlGaN/GaN HEMT with device geometry inputs taken from transmission electron microscope cross sections and calibrated by comparison with measured electrical data comprising standard field-effect transistor metrics and less well-known model parameters. A variety of electrical outputs from the model are compared to experiment, and the level of agreement is reported.

17 citations

Proceedings ArticleDOI
Qihao Song1, Ruizhe Zhang1, Joseph P. Kozak1, Jingcun Liu1, Qiang Li1, Yuhao Zhang1 
21 Mar 2021
TL;DR: In this paper, the surge-energy robustness of a 650-V rated cascode GaN HEMT in the unclamped inductive clamping (UIS) test was investigated.
Abstract: Surge energy robustness of power devices is highly desired in many power applications such as automotive powertrains and power grids. While Si and SiC power MOSFETs withstand surge energy through avalanching, GaN high-electron-mobility transistors (HEMTs) have no avalanche capability. Recent studies have revealed that the p-gate GaN HEMT withstands surge energy through capacitive charging and fails when the peak capacitive voltage reaches its breakdown voltage (BV). This work, for the first time, studies the surge-energy robustness of a 650-V rated cascode GaN HEMT in the unclamped inductive clamping (UIS) test. The cascode GaN HEMT was found to withstand the surge energy via capacitive charging but accompanied by the Si MOSFET avalanching. Two failure modes were observed, both occurring in the GaN HEMT. The first mode is featured by a short between the HEMT gate and drain (cascode source and drain), while the second mode is featured by a short between the HEMT source and drain. Statistical results of multiple devices tested under different load inductance show that the second failure mode predominates. Additionally, the device failure voltage in mode I is statistically higher than that in mode II. Failure analysis of both modes is presented, and the physical explanations of the two modes and their competitions are proposed. These results provide important new insights into the robustness of cascode GaN HEMTs.

16 citations

References
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Dissertation
16 Nov 2009

13 citations


Additional excerpts

  • ...The large-scale mechanics model includes the full width and height of a device including a 100 x 100 μm SiC substrate [43]....

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Proceedings ArticleDOI
27 May 2014
TL;DR: In this article, a coupled small-scale electrothermal model for characterizing AlGaN/GaN HEMTs under direct current (DC) and alternating current (AC) power conditions for various duty cycles was presented.
Abstract: : In this paper, we present a coupled small-scale electrothermal model for characterizing AlGaN/GaN HEMTs under direct current (DC) and alternating current (AC) power conditions for various duty cycles. The calculated electrostatic potential and internal heat generation data are then used in a large-scale mechanics model to determine the development of stress due to the inverse piezoelectric and thermal expansion effects. The electrical characteristics of the modeled device were compared to experimental measurements for validation as well as existing simulation data from literature. The results show that the operating conditions (bias applied and AC duty cycle) strongly impact the temperature within the device and the stress fluctuations during cyclic pulsing conditions. The peak stress from the inverse piezoelectric effect develops rapidly with applied bias and slowly relaxes as the joule heating increases the device temperature during the on state of the pulse leading to cyclic stresses in operation of AlGaN/GaN HEMTs.

12 citations

Proceedings ArticleDOI
01 Nov 2011
TL;DR: In this paper, the authors report that GaN HEMTs developed for RF switching applications do not suffer from an inverse piezo effect related reliability failure mechanism, and a critical voltage was not observed prior to breakdown voltage.
Abstract: The authors report results suggesting that GaN HEMTs developed for RF switching applications do not suffer from an inverse piezo effect related reliability failure mechanism. A critical voltage was not observed prior to breakdown voltage, suggesting a robust GaN HEMT technology well suited for RF switching applications.

11 citations

Proceedings ArticleDOI
N. Braga1, R. V. Mickevicius1, V.S. Rao1, W. Fichtner1, R. Gaska 
01 Jan 2005
TL;DR: In this article, numerical simulations of an AlGaN/GaN heterostructure field effect transistor are presented, including a polarization model that accounts for non-uniform stress fields.
Abstract: We present results from numerical simulations of an AlGaN/GaN heterostructure field effect transistor. Simulations include a polarization model that accounts for non-uniform stress fields and compare results for devices containing uniform and non-uniform stress distributions. Simulations of the electrical characteristics focus on piezoelectric polarization effects. Due to the high stiffness of nitrides, even large stresses in overlayers lead to relatively minor DC and transient electrical effects. Piezoelectric polarization effects are more pronounced for devices with larger AlGaN film strain relaxation.

5 citations


"Transient stress characterization o..." refers background in this paper

  • ...SiNx passivation, in particular, can be deposited in a highly stressed state [16, 17] and the AlGaN layer has large amounts of intrinsic tensile stress...

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01 Jan 2011
TL;DR: In this article, a physics-based finite element model of operation of an AlGaN/GaN HEMT with device geometry in- puts taken from transmission electron microscope cross sections and calibrated by comparison with measured electrical data comprising standard field-effect transistor metrics and less well-known model parameters is presented.
Abstract: We present a physics-based finite-element model of operation of an AlGaN/GaN HEMT with device geometry in- puts taken from transmission electron microscope cross sections and calibrated by comparison with measured electrical data comprising standard field-effect transistor metrics and less well- known model parameters. A variety of electrical outputs from the model are compared to experiment, and the level of agreement is reported. Index Terms—Device model, field-effect transistor (FET), GaN, GaN/AlGaN, high-electron mobility transistor (HEMT), model calibration, model characterization, modulation-doped field effect transistor (MODFET).

1 citations