Research

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14 pages, 4480 KiB

Open AccessFeature PaperArticle

Temperature-Dependent Dynamic on Resistance in Gamma-Irradiated AlGaN/GaN Power HEMTs

by Enrique Maset, Pedro Martín-Holgado, Yolanda Morilla, David Gilabert, Esteban Sanchis-Kilders and Pedro J. Martínez

Appl. Sci. 2022, 12(22), 11578; https://0-doi-org.brum.beds.ac.uk/10.3390/app122211578 - 15 Nov 2022

Viewed by 1168

Abstract

Dynamic R_ON is a key parameter in terms of device reliability and the efficiency of power-switching converters. In this study, commercial off-the-shelf GaN-on-Si power high-electron-mobility transistors (HEMTs) were irradiated using different regimes of accumulative gamma rays with a ⁶⁰Co source of [...] Read more.

Dynamic R_ON is a key parameter in terms of device reliability and the efficiency of power-switching converters. In this study, commercial off-the-shelf GaN-on-Si power high-electron-mobility transistors (HEMTs) were irradiated using different regimes of accumulative gamma rays with a ⁶⁰Co source of photon energy (1.33 MeV), while a base temperature of 53 °C and 133 °C during the irradiation test was applied. This test campaign had the objective of investigating how the combination of gamma irradiation and temperature affects dynamic on-resistance (R_ON) behaviour. The results indicated that gate voltage bias stress affected the degradation of dynamic on-resistance when irradiation was applied, and that temperature was an accelerating factor in dynamic on-resistance degradation. Finally, we obtained a partial reduction in dynamic R_ON when a total ionising dose of around 140 krad(SiO₂) was applied and the base temperature during the irradiation test was not high. Full article

(This article belongs to the Special Issue Robustness and Reliability of GaN Technology in Power Switching Applications)

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17 pages, 1016 KiB

Open AccessArticle

Self-Heating of Annealed Ti/Al/Ni/Au Contacts to Two-Dimensional Electron Gas in AlGaN/GaN Heterostructures

by Emilis Šermukšnis, Justinas Jorudas, Artūr Šimukovič, Vitalij Kovalevskij and Irmantas Kašalynas

Appl. Sci. 2022, 12(21), 11079; https://0-doi-org.brum.beds.ac.uk/10.3390/app122111079 - 01 Nov 2022

Cited by 4 | Viewed by 1412

Abstract

In this work, we investigated the self-heating effects of annealed Ti/Al/Ni/Au ohmic contacts and two-dimensional electron gas (2DEG) in AlGaN/GaN heterostructures under strong electric field by using the short pulse current–voltage and microwave noise measurement techniques. The experimental results demonstrated that the self-heating [...] Read more.

In this work, we investigated the self-heating effects of annealed Ti/Al/Ni/Au ohmic contacts and two-dimensional electron gas (2DEG) in AlGaN/GaN heterostructures under strong electric field by using the short pulse current–voltage and microwave noise measurement techniques. The experimental results demonstrated that the self-heating phenomena in ohmic contacts with the increase of current may dominate over the electrical performances of 2DEG channel. Moreover, the excess noise temperature of contact resistance was found to be more than four times higher than that of 2DEG channel at the same high current density values. The results reveal the importance of self-heating of the ohmic contacts on the device performance under short-duration (only 100 ns) and low-duty-cycle (only 10⁻⁵) pulse regime. Full article

(This article belongs to the Special Issue Robustness and Reliability of GaN Technology in Power Switching Applications)

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21 pages, 8405 KiB

Open AccessFeature PaperArticle

Influence of Quality of Mounting Process of RF Transistors on Their Thermal Parameters and Lifetime

by Krzysztof Górecki, Wojciech Kowalke and Przemysław Ptak

Appl. Sci. 2022, 12(12), 6113; https://0-doi-org.brum.beds.ac.uk/10.3390/app12126113 - 16 Jun 2022

Cited by 5 | Viewed by 1477

Abstract

The paper presents the results of investigations illustrating the influence of imperfections in the soldering process on thermal properties of transistors operating in RF (Radio Frequency) systems. The methods of measurements used to determine the junction and case temperature of the tested transistors [...] Read more.

The paper presents the results of investigations illustrating the influence of imperfections in the soldering process on thermal properties of transistors operating in RF (Radio Frequency) systems. The methods of measurements used to determine the junction and case temperature of the tested transistors and their thermal resistance are described. The results of the performed measurements are presented and discussed, and their statistical analysis is carried out. The correlation between thermal parameters of the tested transistors, parameters of the assembly process and the measurement conditions is investigated. Some calculation results illustrating an influence of device thermal resistance and dissipated power on changing its lifetime are shown and discussed. It is also shown that no correlation between the void sizes and the device thermal resistance and lifetime is observed. Possibilities of improving the assembly process are indicated, which allows extending the expected lifetime of the tested transistors. Full article

(This article belongs to the Special Issue Robustness and Reliability of GaN Technology in Power Switching Applications)

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10 pages, 6955 KiB

Open AccessArticle

GaN-on-Si: Monolithically Integrated All-GaN Drivers for High-Voltage DC-DC Power Conversion

by Chin Hsia and Deng-Fong Lu

Appl. Sci. 2022, 12(10), 5109; https://0-doi-org.brum.beds.ac.uk/10.3390/app12105109 - 19 May 2022

Cited by 5 | Viewed by 1993

Abstract

This paper presents a novel integrated half-bridge driver architecture using GaN-on-Si process for high-speed and high-voltage DC-DC converters. The entire circuit includes only enhancement mode (E-mode) and depletion-mode (D-mode) GaN transistors. The high-side driver circuit adopts the E-stacked E/D-mode (EED) architecture, which can [...] Read more.

This paper presents a novel integrated half-bridge driver architecture using GaN-on-Si process for high-speed and high-voltage DC-DC converters. The entire circuit includes only enhancement mode (E-mode) and depletion-mode (D-mode) GaN transistors. The high-side driver circuit adopts the E-stacked E/D-mode (EED) architecture, which can directly drive the gate of the high-side transistor with a low-voltage signal without using an additional level shifter, which simplifies the design and reduces propagation delay. In addition, the low-side power transistor is driven by stacking two D/E-mode devices. This architecture separates the high-side pulse from the low-side drive signal to prevent false triggering of the low-side driver. The designed fully integrated GaN driver can output a high-voltage pulse wave with an operating frequency greater than 1 MHz when the input voltage is greater than 200 V. The rise and fall times of the high-voltage pulse wave operating at a peak voltage of 200 V are 54.4 ns and 57.6 ns, respectively. The experimental results show that the circuit can effectively drive the half-bridge circuit and be applied to a buck converter. The designed buck converter can deliver up to 20.5 W of output power, and the maximum efficiency achieves 90.7%. Full article

(This article belongs to the Special Issue Robustness and Reliability of GaN Technology in Power Switching Applications)

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8 pages, 7040 KiB

Open AccessArticle

Monolithic Si-Based AlGaN/GaN MIS-HEMTs Comparator and Its High Temperature Characteristics

by Fan Li, Ang Li, Yuhao Zhu, Chengmurong Ding, Yubo Wang, Weisheng Wang, Miao Cui, Yinchao Zhao, Huiqing Wen and Wen Liu

Appl. Sci. 2021, 11(24), 12057; https://0-doi-org.brum.beds.ac.uk/10.3390/app112412057 - 17 Dec 2021

Cited by 2 | Viewed by 3168

Abstract

Monolithic GaN High Electron Mobility Transistor (HEMT)-integrated circuits are a promising application of wide band-gap materials. To date, most GaN-based devices behave as NMOS-like transistors. As only NMOS GaN HEMT is currently commercially available, its control circuit requires special design if monolithic integration [...] Read more.

Monolithic GaN High Electron Mobility Transistor (HEMT)-integrated circuits are a promising application of wide band-gap materials. To date, most GaN-based devices behave as NMOS-like transistors. As only NMOS GaN HEMT is currently commercially available, its control circuit requires special design if monolithic integration is desired. This article analyzes the schematics of a GaN-based comparator, and three comparator structures are compared through ADS simulation. The optimal structure with the bootstrapped technique is fabricated based on AlGaN/GaN Metal–Insulator–Semiconductor (MIS) HEMT with the recessed gate method. The comparator has excellent static characteristics when the reference voltage increases from 3 V to 8 V. Dynamic waveforms from 10 kHz to 1 MHz are also obtained. High-temperature tests from 25

^{°}

C to 250

^{°}

C are applied upon both DC and AC characteristics. The mechanisms of instability issues are explained under dynamic working condition. The results prove that the comparator can be used in the state-of-art mixed-signal circuits, demonstrating the potential for the monolithic all-GaN integrated circuits. Full article

(This article belongs to the Special Issue Robustness and Reliability of GaN Technology in Power Switching Applications)

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8 pages, 31531 KiB

Open AccessArticle

An Accurate Switching Current Measurement Based on Resistive Shunt Applied to Short Circuit GaN HEMT Characterization

by Carmine Abbate, Leandro Colella, Roberto Di Folco, Giovanni Busatto, Emanuele Martano, Simone Palazzo, Annunziata Sanseverino and Francesco Velardi

Appl. Sci. 2021, 11(19), 9138; https://0-doi-org.brum.beds.ac.uk/10.3390/app11199138 - 01 Oct 2021

Cited by 4 | Viewed by 1979

Abstract

The use of a resistive shunt is one of the simplest and most used methods for measuring current in an electronic device. Many researchers use this method to measure drain current during short-circuiting of fast devices such as GaN HEMTs. However, the high [...] Read more.

The use of a resistive shunt is one of the simplest and most used methods for measuring current in an electronic device. Many researchers use this method to measure drain current during short-circuiting of fast devices such as GaN HEMTs. However, the high switching speed of these devices together with the non-ideality of the shunt resistors produces an overestimation of the current in the initial phases of the transient. In this paper, a passive compensation network is proposed, which is formed by adding an inductor to the voltage measurement circuit and allows an accurate measurement of the current using the resistive shunt even in the presence of very fast devices. The proposed method is validated by simulations and experimental measurements. Full article

(This article belongs to the Special Issue Robustness and Reliability of GaN Technology in Power Switching Applications)

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5 pages, 2868 KiB

Open AccessArticle

Design and Switching Characteristics of Flip-Chip GaN Half-Bridge Modules Integrated with Drivers

by Lin Wang, Zhe Cheng, Zhi-Guo Yu, De-Feng Lin, Zhe Liu, Li-Fang Jia and Yun Zhang

Appl. Sci. 2021, 11(15), 7057; https://0-doi-org.brum.beds.ac.uk/10.3390/app11157057 - 30 Jul 2021

Cited by 2 | Viewed by 1780

Abstract

Half-bridge modules with integrated GaN high electron mobility transistors (HEMTs) and driver dies were designed and fabricated in this research. Our design uses flip-chip technology for fabrication, instead of more generally applied wire bonding, to reduce parasitic inductance in both the driver-gate and [...] Read more.

Half-bridge modules with integrated GaN high electron mobility transistors (HEMTs) and driver dies were designed and fabricated in this research. Our design uses flip-chip technology for fabrication, instead of more generally applied wire bonding, to reduce parasitic inductance in both the driver-gate and drain-source loops. Modules were prepared using both methods and the double-pulse test was applied to evaluate and compare their switching characteristics. The gate voltage (

V_{g s}

) waveform of the flip-chip module showed no overshoot during the turn-on period, and a small oscillation during the turn-off period. The probabilities of gate damage and false turn-on were greatly reduced. The inductance in the drain-source loop of the module was measured to be 3.4 nH. The rise and fall times of the drain voltage (

V_{d s}

) were 12.9 and 5.8 ns, respectively, with an overshoot of only 4.8 V during the turn-off period under

V_{d c}

= 100 V. These results indicate that the use of flip-chip technology along with the integration of GaN HEMTs with driver dies can effectively reduce the parasitic inductance and improve the switching performance of GaN half-bridge modules compared to wire bonding. Full article

(This article belongs to the Special Issue Robustness and Reliability of GaN Technology in Power Switching Applications)

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10 pages, 4757 KiB

Open AccessArticle

Investigations about Al and Cu-Based Planar Spiral Inductors on Sapphire for GaN-Based RF Applications

by Chen Lin, Teng Zhan, Junxi Wang, Jinmin Li, Zhiqiang Liu and Xiaoyan Yi

Appl. Sci. 2021, 11(11), 5164; https://0-doi-org.brum.beds.ac.uk/10.3390/app11115164 - 02 Jun 2021

Viewed by 2159

Abstract

Conventionally, Cu is preferred over Al to fabricate integrated inductors with higher quality factors on either silicon or sapphire substrates, profiting from its lower resistivity. However, after investigating and comparing these two kinds of metal multilayers in terms of fabrication process, electrical conductivity, [...] Read more.

Conventionally, Cu is preferred over Al to fabricate integrated inductors with higher quality factors on either silicon or sapphire substrates, profiting from its lower resistivity. However, after investigating and comparing these two kinds of metal multilayers in terms of fabrication process, electrical conductivity, in-depth profile analysis and performance of actual inductors, the Al-based metal multilayer exhibits competitive ability in fabricating thin-film inductors on sapphire compared to Cu-based multilayers. This is attributed to the degradation in electrical conductivity out of oxidation of Cu-based metal sublayers or forming alloys between them. Furthermore, in order to avoid complicated de-embedding procedures in the characterization of the on-chip inductors, a six-element equivalent physical model, which takes the parasitic effect of radio-frequency (RF) test structures into account, is proposed and validated by matching well with embedded measurement results. Full article

(This article belongs to the Special Issue Robustness and Reliability of GaN Technology in Power Switching Applications)

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Review

Jump to: Research

22 pages, 2682 KiB

Open AccessReview

High Frequency, High Efficiency, and High Power Density GaN-Based LLC Resonant Converter: State-of-the-Art and Perspectives

by Seyed Abolfazl Mortazavizadeh, Simone Palazzo, Arturo Amendola, Enzo De Santis, Dario Di Ruzza, Giuseppe Panariello, Annunziata Sanseverino, Francesco Velardi and Giovanni Busatto

Appl. Sci. 2021, 11(23), 11350; https://0-doi-org.brum.beds.ac.uk/10.3390/app112311350 - 30 Nov 2021

Cited by 13 | Viewed by 4517

Abstract

Soft switching for both primary and secondary side devices is available by using LLC converters. This resonant converter is an ideal candidate for today’s high frequency, high efficiency, and high power density applications like adapters, Uninterrupted Power Supplies (UPS), Solid State Transformers (SST), [...] Read more.

Soft switching for both primary and secondary side devices is available by using LLC converters. This resonant converter is an ideal candidate for today’s high frequency, high efficiency, and high power density applications like adapters, Uninterrupted Power Supplies (UPS), Solid State Transformers (SST), electric vehicle battery chargers, renewable energy systems, servers, and telecom systems. Using Gallium-Nitride (GaN)-based power switches in this converter merits more and more switching frequency, power density, and efficiency. Therefore, the present paper focused on GaN-based LLC resonant converters. The converter structure, operation regions, design steps, and drive system are described precisely. Then its losses are discussed, and the magnets and inductance characteristics are investigated. After that, various interleaved topologies, as a solution to improve power density and decrease current ripples, have been discussed. Also, some challenges and concerns related to GaN-based LLC converters have been reviewed. Commercially available power transistors based on various technologies, i.e., GaN HEMT, Silicon (Si) MOSFET, and Silicon Carbide (SiC) have been compared. Finally, the LLC resonant converter has been simulated by taking advantage of LTspice and GaN HEMT merits, as compared with Si MOSFETs. Full article

(This article belongs to the Special Issue Robustness and Reliability of GaN Technology in Power Switching Applications)

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