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arxiv: 2606.28942 · v1 · pith:J6ODXQXDnew · submitted 2026-06-27 · ⚛️ physics.app-ph

Vertical β-Ga₂O₃ Schottky Diodes with Deep-Etch Field Termination using Plasma-free Ga-assisted Etching

Saleh Ahmed Khan , Ahmed Ibreljic , Anhar Bhuiyan This is my paper

Pith reviewed 2026-06-30 08:31 UTC · model grok-4.3

classification ⚛️ physics.app-ph
keywords beta-Ga2O3Schottky barrier diodesfield terminationplasma-free etchingbreakdown voltagemesa structurepower devices
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The pith

Deep-etched mesas formed by Ga-assisted plasma-free etching raise breakdown voltage in β-Ga₂O₃ Schottky diodes from 287 V to 500 V while preserving forward characteristics.

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

The paper establishes that a thermally activated Ga-assisted etch in an LPCVD system creates deep mesa terminations in vertical β-Ga₂O₃ Schottky barrier diodes. These structures redistribute the electric field under reverse bias, lifting breakdown voltage without altering turn-on voltage, ideality factor, or on-resistance compared with planar devices. Capacitance-voltage and temperature-dependent measurements from 25 to 250 °C show stable thermionic emission, uniform doping, and low leakage. TCAD simulations confirm reduced field crowding at the anode edge. The approach supplies a plasma-free route to field termination that avoids crystal damage while enabling higher-voltage operation.

Core claim

The authors demonstrate that deep-etch field termination using Ga-assisted plasma-free etching increases the breakdown voltage of β-Ga₂O₃ Schottky barrier diodes from 287 V to 500 V. The etched devices retain a turn-on voltage of 1.14 V, Schottky barrier height near 1.15–1.23 eV, ideality factor of 1.20, and specific on-resistance of 3.72 mΩ·cm², matching unetched planar references. Temperature sweeps confirm thermionic-emission transport with rectification above 10^5 at 250 °C and simulations show electric-field suppression at the anode edge.

What carries the argument

The deep-etched mesa structure produced by thermally activated Ga-assisted plasma-free etching, which geometrically redistributes the electric field to suppress crowding at the anode edge.

If this is right

  • The same etch process can be applied to other vertical β-Ga₂O₃ power devices to reach higher blocking voltages.
  • Integration into existing LPCVD tools eliminates the need for separate plasma-etch equipment.
  • Stable high-temperature behavior supports use in environments up to at least 250 °C.
  • Uniform post-etch doping profiles enable predictable device scaling.

Where Pith is reading between the lines

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

  • The technique may extend to other wide-bandgap semiconductors that require deep field-termination structures.
  • Combining the mesas with additional edge-termination layers could push breakdown voltages higher still.
  • Direct comparison of long-term reliability between etched and unetched devices would quantify any hidden damage effects.

Load-bearing premise

The etch process introduces no latent crystal damage or surface states that would degrade performance beyond the 25–250 °C range or over extended operating times.

What would settle it

Observation of rising leakage current, falling breakdown voltage, or increased ideality factor after 1000-hour operation at 300 °C or after repeated thermal cycling would falsify the damage-free claim.

Figures

Figures reproduced from arXiv: 2606.28942 by Ahmed Ibreljic, Anhar Bhuiyan, Saleh Ahmed Khan.

Figure 1
Figure 1. Figure 1: Fabrication process flow for planar and mesa [PITH_FULL_IMAGE:figures/full_fig_p002_1.png] view at source ↗
Figure 3
Figure 3. Figure 3: Both devices exhibit a nearly linear 1/C²-V dependence (Figure 3a), consistent with a uniformly doped n￾type drift layer and depletion-region modulation that follows Schottky junction electrostatics. The built-in potential (Vbi), SBH (ΦB) and net carrier concentration (Nd +-Na -) are determined using the following relations [62] for Schottky diodes, 𝑁3 4 − 𝑁5 0 = ( "6+6!7'( , - )' ,$ ) (5) 7' :' = 6 ( "6+6… view at source ↗
Figure 2
Figure 2. Figure 2: (a) Schematic illustration of the mesa-terminated β-Ga₂O₃ Schottky barrier diode. (b) Comparison of the forward and reverse J-V characteristics of the planar and mesa-etched SBDs. (c) Tilted (45°) cross-sectional SEM image of the etched mesa region, illustrating the sidewall profile. (d) Corresponding height profile extracted along the A-A′ direction, indicating an etch depth of ~8.4 µm and a sidewall incl… view at source ↗
Figure 4
Figure 4. Figure 4: Electrical comparison of planar β-Ga₂O₃ SBDs fabricated with (black) and without (blue) exposure to the 1050 °C LPCVD thermal cycle used for the Ga￾assisted etching process. (a) Forward and reverse J-V characteristics. (b) Reverse breakdown characteristics. (c) C-V and 1/C²-V characteristics. (d) Extracted net donor concentration profiles. ND +-NA - (cm-3) Voltage (V) Depth (nm) Capacitance (nF/cm2) (c) (d… view at source ↗
read the original abstract

A deep-etch field termination strategy using a Ga-assisted plasma-free etching technique in a low-pressure chemical vapor deposition (LPCVD) system is demonstrated for $\beta$-Ga$_2$O$_3$ Schottky barrier diodes (SBDs). The thermally activated etching method provides a plasma-free approach for forming deep mesa terminations while maintaining excellent device integrity. The fabricated diodes exhibit excellent forward conduction characteristics with a turn-on voltage of 1.14~V, a Schottky barrier height (SBH) of 1.15~eV, an ideality factor of 1.20, and a specific on-resistance of 3.72~m$\Omega\cdot$cm$^2$, all closely matching those of the unetched planar devices. Capacitance-voltage analysis further confirms a uniform carrier concentration of $2\times10^{16}$~cm$^{-3}$ and an SBH of 1.23~eV, indicating stable electrical characteristics after deep mesa formation. Temperature-dependent electrical measurements from 25 to 250$^\circ$C demonstrate stable thermionic-emission transport behavior, with a gradual increase in on-resistance at elevated temperatures due to phonon-limited carrier mobility. Over this temperature range, the SBH decreases from 1.16 to 1.12~eV, while the ideality factor increases from 1.21 to 1.33. The leakage current remains low throughout the entire temperature range, and the rectification ratio remains above $10^{5}$ even at 250$^\circ$C. Under reverse bias, the diodes exhibit an increase in breakdown voltage from 287V to 500V, confirming the effectiveness of geometric electric-field redistribution achieved by the deep-etched mesa structure. Silvaco TCAD simulations corroborate these experimental observations by showing significant suppression of electric-field crowding near the anode edge. These results establish Ga-assisted plasma-free etching as a reliable, damage-free field termination technique for high-performance $\beta$-Ga$_2$O$_3$ power devices.

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

2 major / 2 minor

Summary. The manuscript demonstrates a plasma-free Ga-assisted etching technique in an LPCVD system to form deep mesa field terminations in vertical β-Ga₂O₃ Schottky barrier diodes. Etched devices show forward I-V parameters (V_on=1.14 V, SBH=1.15 eV, n=1.20, R_on,sp=3.72 mΩ·cm²), C-V doping (2×10¹⁶ cm⁻³), and temperature-dependent thermionic emission (25–250 °C) that closely match unetched planar controls, with breakdown voltage increasing from 287 V to 500 V due to geometric electric-field redistribution, corroborated by Silvaco TCAD simulations showing suppressed edge-field crowding.

Significance. If the result holds, the work establishes a damage-free alternative to plasma etching for field termination in β-Ga₂O₃ power devices, enabling higher breakdown voltages while preserving forward performance and thermal stability; the direct matching of electrical metrics to controls and explicit TCAD validation of the geometric mechanism are particular strengths that isolate the claimed effect.

major comments (2)
  1. [Results section (breakdown and forward characteristics)] Results section (breakdown and forward characteristics): the reported 74% BV increase (287 V to 500 V) and matching forward parameters are presented without stating the number of devices measured, yield, or statistical spread; this weakens the claim that the technique reliably achieves the geometric redistribution effect across devices.
  2. [Abstract and conclusion] Abstract and conclusion: the assertion that the etch is 'damage-free' and establishes a 'reliable' technique rests on short-term I-V, C-V, and 25–250 °C sweeps showing low leakage and stable rectification >10⁵; no post-fabrication stress, long-term bias-temperature, or surface-state density data are provided to support the absence of latent damage.
minor comments (2)
  1. [Temperature-dependent measurements] The temperature-dependent SBH and ideality-factor trends are reported but lack explicit comparison to literature values or discussion of possible interface-state contributions.
  2. [Throughout manuscript] Notation for specific on-resistance is given as mΩ·cm²; ensure consistent use of units and symbols throughout the manuscript and figures.

Simulated Author's Rebuttal

2 responses · 0 unresolved

We thank the referee for the positive evaluation and recommendation for minor revision. The comments are addressed point-by-point below.

read point-by-point responses

  1. Referee: Results section (breakdown and forward characteristics): the reported 74% BV increase (287 V to 500 V) and matching forward parameters are presented without stating the number of devices measured, yield, or statistical spread; this weakens the claim that the technique reliably achieves the geometric redistribution effect across devices.

    Authors: We agree that explicit reporting of device count, yield, and parameter statistics would strengthen the reliability claim. The revised manuscript will include these details from the experimental dataset (number of devices tested, yield, and standard deviations for BV and forward metrics) to better substantiate consistency of the geometric field-redistribution effect. revision: yes

  2. Referee: Abstract and conclusion: the assertion that the etch is 'damage-free' and establishes a 'reliable' technique rests on short-term I-V, C-V, and 25–250 °C sweeps showing low leakage and stable rectification >10⁵; no post-fabrication stress, long-term bias-temperature, or surface-state density data are provided to support the absence of latent damage.

    Authors: The damage-free interpretation is supported by the direct matching of forward I-V, C-V, and temperature-dependent characteristics to unetched planar controls together with stable rectification and thermionic transport. We acknowledge that long-term stress or surface-state data are absent. The abstract and conclusion will be revised to qualify the claim as based on the short-term electrical data and control comparisons presented, without asserting comprehensive long-term reliability. revision: partial

Circularity Check

0 steps flagged

No significant circularity detected

full rationale

The paper reports an experimental device study whose key results (forward I-V parameters, C-V doping, temperature stability, and BV increase from 287 V to 500 V) are obtained directly from measurements and corroborated by independent Silvaco TCAD field simulations. No equations redefine fitted inputs as predictions, no self-citations supply load-bearing uniqueness theorems, and the geometric-field attribution is isolated by explicit controls (matching unetched devices, uniform doping, stable thermionic emission). The derivation chain is therefore self-contained against external benchmarks.

Axiom & Free-Parameter Ledger

0 free parameters · 0 axioms · 0 invented entities

Experimental device-fabrication paper. No free parameters are introduced; the work relies on standard semiconductor transport models (thermionic emission) and TCAD electrostatics. No new entities postulated.

pith-pipeline@v0.9.1-grok · 5927 in / 1142 out tokens · 36632 ms · 2026-06-30T08:31:01.066976+00:00 · methodology

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Reference graph

Works this paper leans on

5 extracted references · 2 canonical work pages

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    2.44 kv Ga2O3 vertical trench Schottky barrier diodes with very low reverse leakage current,

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    work page doi:10.1109/iedm.2018.8614693 2018

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    Gallium flux induced etching of β-Ga₂O₃ in an LPCVD system,

    D. Kumar and A. Verma, “Gallium flux induced etching of β-Ga₂O₃ in an LPCVD system,” J. Vac. Sci. Technol. A, vol. 43, no. 5, p. 053405, Sep. 2025, doi: 10.1116/6.0004596

    work page doi:10.1116/6.0004596 2025

  5. [5]

    High breakdown voltage β-Ga₂O₃ Schottky diodes,

    M. H. Wong, “High breakdown voltage β-Ga₂O₃ Schottky diodes,” in Ultrawide Bandgap β-Ga₂O₃ Semiconductor: Theory and Applications, J. S. Speck and E. Farzana, Eds. Melville, NY, USA: AIP Publishing LLC, 2021, ch. 10, pp. 1–20

    2021