Threshold voltage instability in AlGaN/GaN HEMTs

Chang, Tsin‐Yuan; Hsiao, Tsai-Chu; Huang, Szu-Han; Huang, Chun‐Wei; Wang, Yun-Hsiang; Samudra, Ganesh S.; Liang, Yung C.

doi:10.1109/peds.2015.7203502

Cited by 14 publications

(10 citation statements)

References 5 publications

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“…One of the critical instabilities in GaN MIS-HEMTs is bias temperature instability (BTI), in which electrical parameters, in particular, the device threshold voltage, VT, shift around under prolonged gate bias stress at high temperature [5]. It has been reported that VT shift due to BTI in GaN MIS-HEMTs is much larger than in GaN HEMTs, even at low gate stress, which is detrimental to circuit performance [6]. It is The authors are with Microsystems Technology Laboratories, Massachusetts Institute of Technology, Cambridge, MA 02139 USA (e-mail: alexguo@mit.edu).…”

Section: Introductionmentioning

confidence: 99%

Unified Mechanism for Positive- and Negative-Bias Temperature Instability in GaN MOSFETs

Alamo

2017

IEEE Trans. Electron Devices

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We present a comprehensive study of bias temperature instability (BTI) in GaN MOSFETs under moderate positive and negative gate bias stress. We investigate the evolution of threshold voltage (VT), maximum transconductance (gm,max) and subthreshold swing (S). Our results show a universal continuous, symmetrical and reversible VT shift and gm,max change as gate stress voltage (VGS,stress) increases from-5 V to 5 V at RT. The time evolution of VT is well described by a power law model. The voltage dependence, time dependence and temperature dependence of our results suggest that for moderate gate bias stress, PBTI and NBTI are due to a single reversible mechanism. This is electron trapping/detrapping in pre-existing oxide traps that form a defect band very close to the GaN/oxide interface and extend in energy beyond the conduction band edge of GaN and below the Fermi level at the channel surface at 0 V.

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Section: Introductionmentioning

confidence: 99%

Unified Mechanism for Positive- and Negative-Bias Temperature Instability in GaN MOSFETs

Alamo

2017

IEEE Trans. Electron Devices

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“…In order to assess the threshold voltage stability for the two gate module concepts, double-pulse gate stress experiments have been performed. In particular, pulsed transfer characteristics for different gate stress voltages have been extracted [9]. In this experiment, the gate was stressed with a positive voltage (base line), and the samples of the transfer characteristic were extracted periodically, i. e., the device was periodically switched between a stress phase and a measurement phase.…”

Section: Fabricated Devices and Measurementsmentioning

confidence: 99%

“…A Schottky contact at the p-GaN gate can be used to reduce the gate current by several orders of magnitude [6], [7]. However, as the leakage is reduced, the p-GaN region becomes floating, and unstable operation can result when charge is accumulated in the p-GaN during device operation [8], [9]. Indeed, threshold voltage instabilities have a critical impact on device operation.…”

Section: Introductionmentioning

confidence: 99%

Threshold Voltage Instability in p-GaN Gate AlGaN/GaN HFETs

Sayadi

Iannaccone

Sicre

et al. 2018

IEEE Trans. Electron Devices

189

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We investigate the impact of the gate contact on the threshold voltage stability in p-GaN gate AlGaN/GaN HFETs with double pulse measurements on p-GaN gate devices and with device simulations. We find that, under gate stress, in the case of high-leakage Schottky contact to the p-GaN gate a negative threshold voltage shift results from hole accumulation in the p-GaN region. Conversely, in the case of low-leakage Schottky contact, hole depletion in the p-GaN region gives rise to a positive threshold voltage shift. More generally, we show that an imbalance between the hole tunnelling current through the Schottky barrier and the thermionic current across the AlGaN barrier results in a variation of the total charge stored in the p-GaN region, which in turn is responsible for the observed threshold voltage shift. Finally, we present a simplified equivalent circuit model for the p-GaN gate module.

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“…13,14 Nonetheless, as leakage diminishes, the p-GaN region becomes ungrounded, resulting in unstable operation as charges accumulate within the p-GaN during device operation. 15,16 V TH instabilities indeed exert a notable influence on device operation. Negative V TH shifts can cause erroneous turn-on events, creating a safety issue.…”

mentioning

confidence: 99%

An AlGaN-GaN HEMT with p-GaN Extended Gate for Improvements on Current Dispersion and Breakdown Characteristics

Sriramadasu,

Hsin

2024

ECS J. Solid State Sci. Technol.

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This study introduces a novel p-GaN/AlGaN/GaN heterostructure wafer, implementing a unique p-type GaN gate AlGaN/GaN HEMT configuration. In this design, the p-GaN region extends toward the drain, eliminating the need for a gate electrode. This innovation significantly enhances the HEMT's performance, with a 45.2% increase in breakdown voltage (BV) and a 17% higher threshold voltage (VTH) compared to conventional p-GaN gate HEMTs. The extended gate design redistributes the electric field, acting as a field plate to elevate the breakdown voltage. Furthermore, the proposed device, by reducing 17.4% of the saturation current without increasing the on-resistance, possibly offers improved short-circuit capability.

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Threshold voltage instability in AlGaN/GaN HEMTs

Cited by 14 publications

References 5 publications

Unified Mechanism for Positive- and Negative-Bias Temperature Instability in GaN MOSFETs

Unified Mechanism for Positive- and Negative-Bias Temperature Instability in GaN MOSFETs

Threshold Voltage Instability in p-GaN Gate AlGaN/GaN HFETs

An AlGaN-GaN HEMT with p-GaN Extended Gate for Improvements on Current Dispersion and Breakdown Characteristics

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