Characterizing Threshold Voltage Shifts and Recovery in Schottky Gate and Ohmic Gate GaN HEMTs

Gonzalez, Jose Ortiz; Etoz, Burhan; Alatise, Olayiwola

doi:10.1109/ecce44975.2020.9235650

Cited by 8 publications

(10 citation statements)

References 31 publications

(52 reference statements)

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“…[14,15]. In contrast, at high VGS stress, the VTH shift is negative due to hole trapping at the AlGaN/GaN interface [14,15]. Since the preconditioning pulse imposes the rated VGS stress on the GaN e-HEMT gate, the negative VTH shift reported here is in agreement with the previous studies.…”

Section: (B)supporting

confidence: 91%

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On the Repeatability and Reliability of Threshold Voltage Measurements during Gate Bias Stresses in Wide Bandgap Power Devices

Deb

Gonzalez

Bashar

et al. 2022

2022 IEEE Workshop on Wide Bandgap Power Devices and Applications in Europe (WiPDA Europe)

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This paper investigates the peculiarities and challenges of accurate threshold voltage (VTH) measurement after gate bias stress in SiC MOSFETs and GaN e-HEMTs. Traditional techniques historically used in silicon MOSFETs involve test sequences typically comprising preconditioning, VTH measurement, gate voltage stress and VTH measurement after stress. However, with Wide bandgap (WBG) devices like SiC and GaN transistors, the repeatability of VTH measurement, the impact of VTH measurement duration, delay between successive measurements and the role of preconditioning on the accuracy of VTH are currently under study. With current industrial and academic research interest in bias temperature instability in WBG devices, this paper provides significant insight into how repeatable VTH measurement is in WBG devices since measuring VTH can change it. The impact of repeated measurements on the cumulative VTH shift is investigated in both WBG technologies with different delay times between successive measurements with and without preconditioning. Unipolar and Bipolar preconditioning pulses are compared regarding VTH measurement in SiC MOSFETs.

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Section: (B)supporting

confidence: 91%

“…There is evidence of a cumulative VTH shift due to preconditioning and VTH measurements in the GaN e-HEMTs for both short and long delay times. [14,15]. In contrast, at high VGS stress, the VTH shift is negative due to hole trapping at the AlGaN/GaN interface [14,15].…”

Section: (B)mentioning

confidence: 99%

On the Repeatability and Reliability of Threshold Voltage Measurements during Gate Bias Stresses in Wide Bandgap Power Devices

Deb

Gonzalez

Bashar

et al. 2022

2022 IEEE Workshop on Wide Bandgap Power Devices and Applications in Europe (WiPDA Europe)

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“…shows a more negative shift in VTH after a longer recovery time. This agrees with measurements in [17] which show that VTH shift in GaN e-HEMTs subjected to positive VGS stress are initially positive at short recovery times and subsequently become more negative as the recovery time increases. Additionally, [17] also showed the impact of the stress time on the measured peak shift when the device was stressed using a gate voltage of 5.5 V, positive for short stress times and becoming negative as the stress time was increased.…”

Section: B Impact Of Stress Voltage (High Frequency Pulses)supporting

confidence: 91%

“…This agrees with measurements in [17] which show that VTH shift in GaN e-HEMTs subjected to positive VGS stress are initially positive at short recovery times and subsequently become more negative as the recovery time increases. Additionally, [17] also showed the impact of the stress time on the measured peak shift when the device was stressed using a gate voltage of 5.5 V, positive for short stress times and becoming negative as the stress time was increased. Unlike SiC MOSFETs where a positive VGS stress causes VTH to increase because of negative charge trapping, in GaN e-HEMTs, the VTH shift can be positive or negative depending on the VGS stress magnitude and recovery time.…”

Section: B Impact Of Stress Voltage (High Frequency Pulses)supporting

confidence: 91%

“…The results showed that the polarity of the VTH shift depended on the leakage currents of the Schottky contact. Measurements of VTH instability using the third quadrant forward voltage as a technique were introduced in [17,18]. The measurement results showed an initial positive VTH shift for positive VGS stress at high voltages however as the recovery time was increased, the VTH shift became negative.…”

Section: Introductionmentioning

confidence: 99%

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Unipolar and Bipolar Pulsed Gate Stresses and Threshold Voltage Shifts in GaN e-HEMTs

Deb

Gonzalez

Bashar

et al. 2022

2022 IEEE Energy Conversion Congress and Exposition (ECCE)

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In GaN e-HEMTs, Threshold Voltage (VTH) shift from gate voltage (VGS) stress depends on the VGS magnitude, stress time, recovery time (time between stress removal and VTH measurement), temperature and pulse polarity (0 to + VGS or -VGS to + VGS). In this paper, unipolar (0 to VGS) and bipolar (-VGS to + VGS) pulsed gate stresses have been performed on GaN e-HEMTs with different VGS magnitudes. The pulse frequency ranges from 25 Hz to 200 kHz. The results show negative VTH shifts for unipolar VGS pulses (between 5V and 8V) at long recovery times (above 500 seconds). The VTH shift is proportional to the VGS pulse magnitude. When the recovery time is increased from 50 milliseconds to 500 seconds, the measured VTH shift becomes more negative, indicating a faster release of trapped electrons than holes. In bipolar stresses, results show both positive and negative VTH shifts with no clear magnitude or frequency dependencies.

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Stability of GaN HEMT Device Under Static and Dynamic Gate Stress

Gao,

Zhong,

Zhang

et al. 2024

IEEE J. Electron Devices Soc.

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In this work, we investigated the stability of a p-GaN gate with high electron mobility transistors (HEMTs) including an internal integrated gate circuit. A circuit was designed to improve p-GaN gate stability by using capacitance to release the hole into the p-GaN layer to mitigate the threshold voltage shift. Through pulse I-V measurement and positive bias temperature instability (PBTI) test, the carrier transporting behavior in the gate region achieved dynamic equilibrium at 5 V gate bias. The positive gate shift (ΔVTH) of 0.4 V is observed with increasing voltage from 3 V to 8 V; ΔVTH initially drops smoothly after release stresses by external capacitance discharge. Finally, integrated passive components and p-GaN gate HEMT circuit are recommended to mitigate the VTH instability for E-mode HEMT.

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Characterizing Threshold Voltage Shifts and Recovery in Schottky Gate and Ohmic Gate GaN HEMTs

Abstract: Please refer to published version for the most recent bibliographic citation information. If a published version is known of, the repository item page linked to above, will contain details on accessing it.

Cited by 8 publications

References 31 publications

On the Repeatability and Reliability of Threshold Voltage Measurements during Gate Bias Stresses in Wide Bandgap Power Devices

On the Repeatability and Reliability of Threshold Voltage Measurements during Gate Bias Stresses in Wide Bandgap Power Devices

Unipolar and Bipolar Pulsed Gate Stresses and Threshold Voltage Shifts in GaN e-HEMTs

Stability of GaN HEMT Device Under Static and Dynamic Gate Stress

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