Investigation of Thermally Induced Threshold Voltage Shift in Normally-OFF p-GaN Gate HEMTs

Wang, Huan; Lin, Yan; Jiang, Junsong; Dong, Dan; Ji, Fangzheng; Zhang, Meng; Jiang, Ming; Gan, Wei; Li, Baikui; Wang, Maojun; Wei, Jin; Tang, Xi; Hu, Cungang; Cao, Wenping

doi:10.1109/ted.2022.3157805

Cited by 12 publications

(6 citation statements)

References 35 publications

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“…Gallium nitride high-electron-mobility transistors (GaN HEMTs) have been widely used in both radio frequency and power electronics [ 1 , 2 , 3 ], thanks to the superior performance in switching speed and switching losses [ 4 , 5 , 6 ]. For this new technique, the bias temperature instability (BTI) effect is one of the most crucial reliability problems that often take place, especially when the GaN HEMTs are operating under positive gate voltage bias [ 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 ]. To achieve an enhancement-mode operation, two gate architectures, including p-GaN gate HEMTs with a Schottky gate terminal and gate injection transistors (GIT) with an Ohmic gate terminal [ 5 ], have been adopted for mass production.…”

Section: Introductionmentioning

confidence: 99%

Revealing the Mechanism of the Bias Temperature Instability Effect of p-GaN Gate HEMTs by Time-Dependent Gate Breakdown Stress and Fast Sweeping Characterization

Li,

Wang,

Zhang

et al. 2023

Micromachines

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The bias temperature instability (BTI) effect of p-GaN gate high-electron-mobility transistors (HEMTs) is a serious problem for reliability. To uncover the essential cause of this effect, in this paper, we precisely monitored the shifting process of the threshold voltage (VTH) of HEMTs under BTI stress by fast sweeping characterizations. The HEMTs without time-dependent gate breakdown (TDGB) stress featured a high VTH shift of 0.62 V. In contrast, the HEMT that underwent 424 s of TDGB stress clearly saw a limited VTH shift of 0.16 V. The mechanism is that the TDGB stress can induce a Schottky barrier lowering effect on the metal/p-GaN junction, thus boosting the hole injection from the gate metal to the p-GaN layer. This hole injection eventually improves the VTH stability by replenishing the holes lost under BTI stress. It is the first time that we experimentally proved that the BTI effect of p-GaN gate HEMTs was directly dominated by the gate Schottky barrier that impeded the hole supply to the p-GaN layer.

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Section: Introductionmentioning

confidence: 99%

Revealing the Mechanism of the Bias Temperature Instability Effect of p-GaN Gate HEMTs by Time-Dependent Gate Breakdown Stress and Fast Sweeping Characterization

Li,

Wang,

Zhang

et al. 2023

Micromachines

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“…The PL spectrum for GaN on Si exhibited a broader peak with additional features in comparison to GaN on QST, potentially indicating a higher density of trap states in the Si substrate material. Analyzing the spectral data, the GaN on QST peak was discerned to be narrower and more intense at the band edge, coupled with fewer long-wavelength emissions, thus implying an improved material quality, enhanced carrier concentration, and a reduced number of trap states in comparison to GaN on Si [17,18].…”

Section: Resultsmentioning

confidence: 99%

Study of 1500 V AlGaN/GaN High-Electron-Mobility Transistors Grown on Engineered Substrates

Liu,

Chen,

Chuang

et al. 2024

Electronics

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In this study, we demonstrate breakdown voltage at 1500 V of GaN on a QST power device. The high breakdown voltage and low current collapse performance can be attributed to the higher quality of GaN buffer layers grown on QST substrates. This is primarily due to the matched coefficient of thermal expansion (CTE) with GaN and the enhanced mechanical strength. Based on computer-aided design (TCAD) simulations, the strong electric-field-induced trap-assisted thermionic field emissions (TA-TFEs) in the GaN on QST could be eliminated in the GaN buffer. This demonstration showed the potential of GaN on QST, and promises well-controlled performance and reliability under high-power operation conditions.

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“…In order to analyze the relationship between the ohmic-type gate devices, the Schottky-type gate devices, and V TH drift, Wang et al [ 37 ] tested and analyzed the relevant characteristics of ohmic gate devices and Schottky gate devices.…”

Section: Reasons For V Th Driftmentioning

confidence: 99%

“…The I-V characteristics between two contact pads with different channel distances were shown. The test revealed a knee point voltage, which may have been caused by the surface of the GaN material being affected during the fabrication of the device [ 37 ]. It was shown that the presence of the knee voltage ( V Knee ) makes the effective bias on the p-i-n junction ( V p-i-n) smaller than the applied gate bias ( V Bias ), which, in turn, affects the conduction of the ohmic-type gate device.…”

Section: Reasons For V Th Driftmentioning

confidence: 99%

“…This also indicated that the positive threshold voltage shift under HTRB showed a positive correlation with temperature. Under thermal stress conditions, Wang et al [37] studied the phenomenon of VTH shift in GaN HEMTs based on an ohmic-type gate and a Schottky-type gate. The variation in VTH shift with temperature was tested for both Schottky-type gate devices and ohmictype gate devices when VDS was set to 5 V. The GaN HEMT device with a Schottky-type gate showed an increase in the value of VTH as the temperature increased.…”

Section: Effects Of Thermal Stressmentioning

confidence: 99%

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Research on the Reliability of Threshold Voltage Based on GaN High-Electron-Mobility Transistors

Dai,

Wang,

2024

Micromachines

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With the development of high-voltage and high-frequency switching circuits, GaN high-electron-mobility transistor (HEMT) devices with high bandwidth, high electron mobility, and high breakdown voltage have become an important research topic in this field. It has been found that GaN HEMT devices have a drift in threshold voltage under the conditions of temperature and gate stress changes. Under high-temperature conditions, the difference in gate contact also causes the threshold voltage to shift. The variation in the threshold voltage affects the stability of the device as well as the overall circuit performance. Therefore, in this paper, a review of previous work is presented. Temperature variation, gate stress variation, and gate contact variation are investigated to analyze the physical mechanisms that generate the threshold voltage (VTH) drift phenomenon in GaN HEMT devices. Finally, improvement methods suitable for GaN HEMT devices under high-temperature and high-voltage conditions are summarized.

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Investigation of Thermally Induced Threshold Voltage Shift in Normally-OFF p-GaN Gate HEMTs

Cited by 12 publications

References 35 publications

Revealing the Mechanism of the Bias Temperature Instability Effect of p-GaN Gate HEMTs by Time-Dependent Gate Breakdown Stress and Fast Sweeping Characterization

Revealing the Mechanism of the Bias Temperature Instability Effect of p-GaN Gate HEMTs by Time-Dependent Gate Breakdown Stress and Fast Sweeping Characterization

Study of 1500 V AlGaN/GaN High-Electron-Mobility Transistors Grown on Engineered Substrates

Research on the Reliability of Threshold Voltage Based on GaN High-Electron-Mobility Transistors

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