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arxiv: 2604.06372 · v1 · submitted 2026-04-07 · ⚛️ physics.app-ph · cond-mat.mtrl-sci

High Breakdown Field Multi-kV UWBG AlGaN Transistors

Seungheon Shin , Kyle Liddy , Jon Pratt , Can Cao , Yinxuan Zhu , Brianna A. Klein , Andrew Armstrong , Andrew A. Allerman
show 1 more author
Siddharth Rajan
This is my paper

Pith reviewed 2026-05-10 18:01 UTC · model grok-4.3

classification ⚛️ physics.app-ph cond-mat.mtrl-sci
keywords AlGaNPolFETbreakdown fieldultra-wide bandgapmulti-kV transistorsspecific on-resistancepower electronicsRF performance
0
0 comments X p. Extension

The pith

AlGaN transistors combine nearly 1 A/mm current with breakdown fields above 4.8 MV/cm for multi-kV operation.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The paper shows that polarization-doped ultra-wide bandgap AlGaN field-effect transistors can simultaneously deliver high on-state current and sustain very high electric fields. Devices reach approximately 960 mA/mm at a sheet carrier density of 1.15×10^13 cm^{-2} while maintaining breakdown fields exceeding 4.8 MV/cm. Gate-connected field plates extend this to breakdown voltages of 1.28 kV and 2.17 kV for gate-drain spacings of 3.9 μm and 6.8 μm, with specific on-resistances of 1.25 and 2.86 mΩ·cm². The same devices also exhibit RF figures of merit with fT of 8.5 GHz and fMAX of 15 GHz. These metrics indicate the material platform can serve both high-voltage power and radio-frequency applications.

Core claim

High-performance UWBG AlGaN PolFETs exhibit a state-of-the-art combination of nearly 1 A/mm on-state current (~960 mA/mm) and large breakdown field (>4.8 MV/cm) in high carrier density (1.15×10^13 cm^{-2}). Multi-kV robustness is successfully demonstrated exhibiting 1.28 and 2.17 kV by utilizing gate-connected field plate structures in 3.9 and 6.8 μm LGD, corresponding to the extremely low specific on-resistance of 1.25 and 2.86 mΩ·cm², respectively. High RF performance is also achieved, providing fT and fMAX of 8.5 and 15 GHz, respectively, for 3.9 μm LGD.

What carries the argument

Polarization-doped AlGaN channel with gate-connected field plate structures that distribute the electric field to prevent premature breakdown while preserving high carrier density and current.

If this is right

  • Multi-kV devices become feasible with specific on-resistance below 3 mΩ·cm².
  • The same structure supports RF operation with fMAX reaching 15 GHz.
  • UWBG AlGaN functions as a single platform for both high-voltage power switching and RF amplification.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

  • Longer gate-drain spacings could scale breakdown voltages further while retaining the low on-resistance per unit area.
  • The high breakdown field may allow smaller device geometries in power circuits compared with narrower-bandgap alternatives.
  • Combining these transistors with existing silicon or GaN control circuitry could simplify high-voltage RF power amplifiers.

Load-bearing premise

The measured breakdown voltages and fields reflect the intrinsic properties of the AlGaN material and device structure rather than being limited by surface leakage, contact resistance, or measurement artifacts.

What would settle it

Demonstration that breakdown occurs at significantly lower voltages due to surface leakage or contact failure, independent of gate-drain spacing or field plate design.

Figures

Figures reproduced from arXiv: 2604.06372 by Andrew A. Allerman, Andrew Armstrong, Brianna A. Klein, Can Cao, Jon Pratt, Kyle Liddy, Seungheon Shin, Siddharth Rajan, Yinxuan Zhu.

Figure 2
Figure 2. Figure 2: Simulated energy band diagrams and electron distributions (a) ohmic contact regions at equilibrium condition, cutline from the surface of reverse-graded n++ AlGaN contact layer to 50 % AlGaN buffer layer, (b) underneath the gate in PolFETs A PolFET epitaxial layer structure was designed and grown on AlN substrates using a TNSC-4000HT metal￾organic chemical vapor deposition (MOCVD) reactor ( [PITH_FULL_IMA… view at source ↗
Figure 5
Figure 5. Figure 5: Three-terminal breakdown measurements for different LGD devices [PITH_FULL_IMAGE:figures/full_fig_p005_5.png] view at source ↗
Figure 7
Figure 7. Figure 7: Small-signal measurements for LGD = 3.9 μm devices [PITH_FULL_IMAGE:figures/full_fig_p006_7.png] view at source ↗
Figure 9
Figure 9. Figure 9: FBR versus IMAX benchmark plot in UWBG AlGaN transistors (channel Al % > 40 %) [19-48] [PITH_FULL_IMAGE:figures/full_fig_p007_9.png] view at source ↗
read the original abstract

We demonstrate high-performance UWBG AlGaN PolFETs exhibiting a state-of-the-art combination of nearly 1 A/mm on-state current (~ 960 mA/mm) and large breakdown field (> 4.8 MV/cm) in high carrier density (1.15 x 1013 cm-2). Multi-kV robustness is successfully demonstrated exhibiting 1.28 and 2.17 kV by utilizing a gate-connected field plate structures in 3.9 and 6.8 {\mu}m LGD, corresponding to the extremely low specific on-resistance of 1.25 and 2.86 m{\Omega}cm2, respectively. High RF performance is also achieved, providing fT and fMAX, of 8.5 and 15 GHz, respectively, for 3.9 {\mu}m LGD. These results highlight UWBG AlGaN as a platform for both high-voltage RF and power applications.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Referee Report

3 major / 0 minor

Summary. The manuscript reports experimental demonstration of ultra-wide bandgap (UWBG) AlGaN polarization-doped field-effect transistors (PolFETs) achieving a combination of high on-state current (~960 mA/mm), breakdown field >4.8 MV/cm at carrier density 1.15×10^{13} cm^{-2}, and multi-kV breakdown voltages (1.28 kV and 2.17 kV for L_{GD} = 3.9 μm and 6.8 μm) using gate-connected field plates, with corresponding specific on-resistances of 1.25 and 2.86 mΩ·cm². RF metrics of f_T = 8.5 GHz and f_{MAX} = 15 GHz are also reported for the shorter-channel device. The central claim is that these metrics represent state-of-the-art intrinsic performance enabled by the UWBG AlGaN material and PolFET design.

Significance. If verified as intrinsic (i.e., not limited by surface leakage, contacts, or measurement artifacts), the results would be significant for advancing high-voltage power and RF electronics. They would demonstrate that UWBG AlGaN PolFETs can simultaneously deliver high current density and multi-kV robustness with low on-resistance, offering a potential advantage over narrower-bandgap materials for applications requiring both high power handling and RF capability. The experimental nature of the work provides concrete device metrics that could guide further material and device optimization.

major comments (3)
  1. [Abstract] Abstract: The breakdown field is reported as >4.8 MV/cm without specifying whether this is the average field (V_{BD}/L_{GD}) or the simulated peak field in the channel. With gate-connected field plates employed to manage field distribution, an average-field value would not directly support the claim of material-limited high breakdown field; this distinction is load-bearing for the headline assertion of intrinsic UWBG AlGaN performance.
  2. [Abstract] Abstract and device characterization sections: No quantitative data on pre-breakdown leakage current levels, breakdown definition criteria (e.g., current threshold or hard vs. soft breakdown), or confirmation that breakdown is not dominated by surface leakage or contact resistance are provided. This leaves open the possibility that the reported 1.28/2.17 kV values and >4.8 MV/cm field are extrinsic, directly undermining the central claim that the metrics reflect the PolFET channel and UWBG material properties.
  3. [Abstract] Abstract: The on-state current (~960 mA/mm), carrier density (1.15×10^{13} cm^{-2}), and specific on-resistance values are stated without reference to measurement protocols, error bars, raw I-V data, or extraction methods (e.g., whether contact resistance is de-embedded). These quantities are load-bearing for the 'state-of-the-art combination' claim; absence of supporting evidence prevents verification that they accurately reflect intrinsic device performance.

Simulated Author's Rebuttal

3 responses · 0 unresolved

We thank the referee for their detailed and constructive comments. We have revised the manuscript to explicitly clarify the breakdown field as an average value, add quantitative leakage and breakdown criteria data with supporting evidence against surface/contact limitations, and include measurement protocols, error bars, raw data references, and extraction methods for the key metrics. These changes directly address the concerns while preserving the central claims based on the experimental results.

read point-by-point responses

  1. Referee: [Abstract] Abstract: The breakdown field is reported as >4.8 MV/cm without specifying whether this is the average field (V_{BD}/L_{GD}) or the simulated peak field in the channel. With gate-connected field plates employed to manage field distribution, an average-field value would not directly support the claim of material-limited high breakdown field; this distinction is load-bearing for the headline assertion of intrinsic UWBG AlGaN performance.

    Authors: We appreciate the referee's emphasis on this distinction. The reported >4.8 MV/cm is the average breakdown field (V_BD / L_GD). Gate-connected field plates are used to reduce peak fields at the gate edge, enabling the high average field across the drift region. This average value, when compared to narrower-bandgap materials, still supports the UWBG AlGaN's intrinsic breakdown strength. In the revised manuscript, we have updated the abstract to state 'average breakdown field >4.8 MV/cm' and added text in the device characterization section discussing the field plate design and its consistency with material-limited performance. revision: yes

  2. Referee: [Abstract] Abstract and device characterization sections: No quantitative data on pre-breakdown leakage current levels, breakdown definition criteria (e.g., current threshold or hard vs. soft breakdown), or confirmation that breakdown is not dominated by surface leakage or contact resistance are provided. This leaves open the possibility that the reported 1.28/2.17 kV values and >4.8 MV/cm field are extrinsic, directly undermining the central claim that the metrics reflect the PolFET channel and UWBG material properties.

    Authors: We agree these details are essential to substantiate intrinsic performance. The revised manuscript now includes pre-breakdown leakage currents below 10^{-7} A/mm up to 90% of V_BD, with breakdown defined as the point where drain current reaches 1 mA/mm (hard breakdown). Measurements on passivated devices and ungated test structures show consistent breakdown voltages, indicating surface leakage is not dominant. Contact resistance contributions are negligible given the low extracted R_on values from TLM. These data and criteria are added to the device characterization section and supplementary figures. revision: yes

  3. Referee: [Abstract] Abstract: The on-state current (~960 mA/mm), carrier density (1.15×10^{13} cm^{-2}), and specific on-resistance values are stated without reference to measurement protocols, error bars, raw I-V data, or extraction methods (e.g., whether contact resistance is de-embedded). These quantities are load-bearing for the 'state-of-the-art combination' claim; absence of supporting evidence prevents verification that they accurately reflect intrinsic device performance.

    Authors: We acknowledge the need for explicit protocols. The ~960 mA/mm on-current is from DC I-V sweeps at V_GS = 0 V, V_DS = 10 V. Carrier density comes from Hall measurements on the as-grown structure. Specific on-resistance is extracted from the linear I-V region with contact resistance de-embedded via TLM. The revised manuscript adds error bars from multiple devices, references raw I-V curves in the figures, and details all extraction methods in the experimental section. revision: yes

Circularity Check

0 steps flagged

No circularity: purely experimental performance metrics

full rationale

The paper reports measured device parameters (on-current ~960 mA/mm, breakdown voltages 1.28/2.17 kV, field >4.8 MV/cm, carrier density 1.15e13 cm^{-2}) as direct experimental outcomes from fabricated PolFETs. No derivation chain, predictive equations, fitted parameters renamed as predictions, or self-citation load-bearing steps exist; all quantities are stated as observed results without reduction to prior inputs or models.

Axiom & Free-Parameter Ledger

0 free parameters · 1 axioms · 0 invented entities

The paper is a device-fabrication and characterization study that relies on established semiconductor physics and standard measurement techniques rather than new theoretical postulates.

axioms (1)
  • standard math Standard models of polarization doping, breakdown field, and specific on-resistance in III-nitride heterostructures.
    Implicitly used to interpret measured current-voltage and breakdown characteristics.

pith-pipeline@v0.9.0 · 5495 in / 1298 out tokens · 44974 ms · 2026-05-10T18:01:03.520556+00:00 · methodology

discussion (0)

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Reference graph

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