Impact of undoped channel thickness and carbon concentration on AlN/GaN-on-SiC HEMT performances

Harrouche, Kathia; Venkatachalam, Srisaran; Grandpierron, François; Okada, Étienne; Medjdoub, Farid

doi:10.35848/1882-0786/ac9c46

Cited by 11 publications

(9 citation statements)

References 33 publications

(46 reference statements)

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“…The DIBL simulated is at per the experimental DIBL of the 0.4 μm gate length device. DIBL values of GaN HEMT are reported as 45mV V −1 for 90 nm gate length [47], 26mV V −1 100 nm gate length [48], 12 mV V −1 for 140nm gate length [49], 100 nm 40mV V −1 for 100 gate length [50]. Observing these results, it can be concluded that our device shows improvement after recess.…”

Section: Simulation Study To Suppress Scesmentioning

confidence: 51%

Investigation of RF performance of Ku-band GaN HEMT device and an in-depth analysis of short channel effects

Raychaudhuri,

Mukherjee,

Kumar

et al. 2024

Phys. Scr.

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In this paper, we have characterized an AlGaN/GaN High Electron Mobility Transistor (HEMT) with a short gate length (Lg ≈ 0.15μm). We have studied the effect of short gate length on the small signal parameters, linearity parameters and gm-gd ratio in GaN HEMT devices. To understand how scaling results in the variation of the above-mentioned parameters a comparative study with higher gate length devices on similar heterostructure is also presented here. We have scaled down the gate length but the barrier thickness(tbar) remained same which affects the aspect ratio (Lg/tbar) of the device and its inseparable consequences are the prominent short channel effects (SCEs) barring the optimum output performance of the device. These interesting phenomena were studied in detail and explored over a temperature range of -40 oC to 80 oC. To the best of our knowledge this paper explores temperature dependence of SCEs of GaN HEMT for the first time. With an approach to reduce the impact of SCEs a simulation study in Silvaco TCAD was carried out and it is observed that a recessed gate structure on conventional heterostructure successfully reduces SCEs and improves RF performance of the device. This work gives an overall view of gate length scaling on conventional AlGaN/GaN HEMTs.

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Section: Simulation Study To Suppress Scesmentioning

confidence: 51%

Investigation of RF performance of Ku-band GaN HEMT device and an in-depth analysis of short channel effects

Raychaudhuri,

Mukherjee,

Kumar

et al. 2024

Phys. Scr.

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“…One option consists in adopting a wider bandgap material for the top barrier layer, thus achieving a high 2DEG density even with a thin barrier thickness. To this aim, researchers have studied devices using thin AlN barriers [19], [20], [21], [40], InAl(Ga)N ternary and quaternary barriers [41], [42], [43], and ScAlN barriers [44], [45]; however, the study of the reliability of devices incorporating these new materials is still at its initial stage.…”

Section: Short-channel Effects In Gan Hemtsmentioning

confidence: 99%

Microwave and Millimeter-Wave GaN HEMTs: Impact of Epitaxial Structure on Short-Channel Effects, Electron Trapping, and Reliability

Zanoni,

De Santi,

Gao

et al. 2024

IEEE Trans. Electron Devices

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Application of gallium nitride high-electronmobility transistors (GaN HEMTs) to millimeter-wave power amplifiers requires gate length scaling below 150 nm: in order to control short-channel effects, the gate-to-channel distance must be decreased, and the device epitaxial structure has to be completely redesigned. A high 2-D electron gas (2DEG) carrier density can be preserved even with a very thin top barrier layer by substituting AlGaN with AlN, InAl(Ga)N, or ScAlN. Moreover, to prevent interaction of hot electrons with compensating impurities and defects in the doped GaN buffer, the latter has to be separated from the channel by a back barrier. Other device designs consist in adopting a graded channel (which controls the electric field) or to adopt nitrogen-polar (N-polar) GaN growth (which decreases the distance between gate and channel, thus attenuating short-channel effects). The aim of this article is to review the various options for controlling short-channel effects, improve off-state characteristics, and reduce drain-source leakage current. Advantages and potential drawbacks of each proposed solution are analyzed in terms of current collapse (CC), dispersion effects, and reliability.

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“…SiC substrates. A total of four structures have been realized, consisting of an AlN nucleation layer and a 5 × 10 18 cm −3 carbon-doped GaN buffer allowing significantly reduced trapping effects when located away from the channel [ 33 ]. This is followed by a 100 nm AlGaN back barrier layer with an Al-content varying from 4% to 25% in order to evaluate the impact on the electron confinement.…”

Section: Device Technologymentioning

confidence: 99%

“…This requires extensive buffer engineering. Recently, we evaluated the impact of various carbon-doping concentrations into the buffer with different undoped GaN channel thickness on the device performance [ 33 ]. It was shown that a thin GaN channel, typically below 150 nm, combined with a high carbon concentration into the buffer leads not only to a high electron confinement under high drain bias for 100 nm GaN transistors, but also low leakage current at the expense of trapping effects.…”

Section: Introductionmentioning

confidence: 99%

Low Trapping Effects and High Electron Confinement in Short AlN/GaN-On-SiC HEMTs by Means of a Thin AlGaN Back Barrier

et al. 2023

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In this paper, we report on an enhancement of mm-wave power performances with a vertically scaled AlN/GaN heterostructure. An AlGaN back barrier is introduced underneath a non-intentionally doped GaN channel layer, enabling the prevention of punch-through effects and related drain leakage current under a high electric field while using a moderate carbon concentration into the buffer. By carefully tuning the Al concentration into the back barrier layer, the optimized heterostructure offers a unique combination of electron confinement and low trapping effects up to high drain bias for a gate length as short as 100 nm. Consequently, pulsed (CW) Load-Pull measurements at 40 GHz revealed outstanding performances with a record power-added efficiency of 70% (66%) under high output power density at VDS = 20 V. These results demonstrate the interest of this approach for future millimeter-wave applications.

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Impact of undoped channel thickness and carbon concentration on AlN/GaN-on-SiC HEMT performances

Cited by 11 publications

References 33 publications

Investigation of RF performance of Ku-band GaN HEMT device and an in-depth analysis of short channel effects

Investigation of RF performance of Ku-band GaN HEMT device and an in-depth analysis of short channel effects

Microwave and Millimeter-Wave GaN HEMTs: Impact of Epitaxial Structure on Short-Channel Effects, Electron Trapping, and Reliability

Low Trapping Effects and High Electron Confinement in Short AlN/GaN-On-SiC HEMTs by Means of a Thin AlGaN Back Barrier

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