Semi-insulating GaN for vertical structures: role of substrate selection and growth pressure

Šichman, Peter; Hasenöhrl, S.; Stoklas, R.; Priesol, J.; Dobročka, Edmund; Hašc̆ı́k, Š.; Gucmann, Filip; Vincze, Á.; Chvála, Aleš; Marek, Juraj; Šatka, A.; Kuzmı́k, J.

doi:10.1016/j.mssp.2020.105203

Cited by 7 publications

(10 citation statements)

References 18 publications

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“…[16] Nevertheless, suppressed trapping in the case of 200 ns pulse can be linked to the vertical transistor geometry, restriction of the C-doping to the channel layer and to low defects density in the homo-epitaxial GaN drift layer. [3] Still, some minor trapping in the C-doped channel might be responsible for a kink effect of 200 ns pulsed output characteristics, as shown in the Figure 5, analogously to earlier analyzed planar transistors when trapped electrons below the gate shifted the threshold voltage. [17] Marginal trapping has been confirmed also by performing twochannel pulsed operation, as shown in Figure 7, showing low trapping also for the quiescent point of VGS = 0 V, VDS = 10 V.…”

Section: Resultssupporting

confidence: 68%

“…

Recently, we have suggested that the vertical transistor processing can be simplified by using a C-doped semi-insulating (SI) GaN as a channel layer. [3,4] Elsewhere, unspecified C-doping was introduced in the channel of the vertical normally off FET to compensate residual donors, still the n-type conduction of the GaN prevailed showing free-electron concentration (n) of %3 Â 10 15 cm À3 . [5] Consequently, the width of the channel depletion region (w) induced by the grounded gate was still insufficient to avoid necessity of the channel nanopatterning if normally off behavior was expected.

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confidence: 99%

“…[7] Nevertheless, earlier we have shown that by reaching C concentration between 1 Â 10 17 and 6 Â 10 18 cm À3 , GaN became highly insulating with a breakdown voltage between 45 and 350 V of a 1.3 μm thick layer. [3,4] We suggested, that while C-related acceptors %0.9 eV above the valence band are responsible for a compensation of residual donors, current blocking is controlled by an additional defect-related acceptor level %0.6 eV bellow the conduction band. This way, an avalanche breakdown could be reached for a sufficiently high C doping, [4] while channel opening could be provided by a positive gate bias along trench openings.…”

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confidence: 99%

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Vertical GaN Transistor with Semi‐Insulating Channel

Šichman

Stoklas

Hasenöhrl

et al. 2023

Physica Status Solidi (a)

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Herein, vertical GaN transistors with a semi‐insulating (SI) 1.3 μm thick channel layer and C doping of 1 × 1017 cm−3 are studied. Structures are grown using a metal–organic chemical vapor deposition on conductive GaN substrates. SI GaN is sandwiched between 2.5 μm thick n‐GaN drift layer (Si doping of ≈ 1 × 1017 cm−3) and a top n‐GaN contact layer. A circular mesa region with a diameter of 180 μm is patterned using a deep dry etching. The gate contact formed on the mesa sidewall is insulated from the vertical channel using a 20 nm thick Al2O3 grown by an atomic layer deposition. Despite a robust layout, transistors transfer characteristics indicate normally off behavior if extracted from the linearly scaled current–voltage characteristics and an open channel drain current of 30 mA at the gate bias of 4 V. Achieved on/off ratio is 107 at −2 V subthreshold gate bias when the full channel depletion is reached. And, 200 ns long gate pulse characteristics show only a marginal trapping even though no post‐metallization annealing is performed. By comparing experimental results with modeling, mobility of free electrons in the channel is found to be about 45 cm2 V−1 s−1.

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Section: Resultssupporting

confidence: 68%

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confidence: 99%

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confidence: 99%

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Vertical GaN Transistor with Semi‐Insulating Channel

Šichman

Stoklas

Hasenöhrl

et al. 2023

Physica Status Solidi (a)

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“…[1][2][3][4][5][6] Gallium nitride (GaN) is a fascinating semiconductor, which extensively applies in gas sensors, high power electronic, solar cell and light emitting diodes (LED), etc. [7][8][9] Similar to the grapheme, the monolayer GaN has reproducible electronic properties because of the exposed GaN surface, which is used in high power and high frequency applications. 10,11 The calculated band gap of the GaN monolayer is about 2.130 eV.…”

Section: Introductionmentioning

confidence: 99%

“…With the wide band gap and high‐breakdown electronic field, the III–V semiconductors have received great attention in modern society 1‐6 . Gallium nitride (GaN) is a fascinating semiconductor, which extensively applies in gas sensors, high power electronic, solar cell and light emitting diodes (LED), etc 7‐9 . Similar to the grapheme, the monolayer GaN has reproducible electronic properties because of the exposed GaN surface, which is used in high power and high frequency applications 10,11 .…”

Section: Introductionmentioning

confidence: 99%

Influence of N‐vacancy on the electronic and optical properties of bulk GaN from first‐principles investigations

Pan¹

2021

Intl J of Energy Research

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Gallium nitride (GaN) is a promising semiconductor material for the application of the high power electronic, optoelectronic, laser diodes, etc. The previous works have been focused on the electronic and optical properties of the monolayer GaN. However, the structural, electronic and optical properties of the bulk GaN are unclear. In particular, the role of N-vacancy on the electronic and optical properties of the bulk GaN is unknown. In this work, we apply first-principles calculations to study the influence of N-vacancy on the structural, electronic and optical properties of the bulk GaN. Three bulk GaN: hexagonal (P63/mc), cubic (F-43m) and cubic (Fm-3m) are considered. The result shows that the N-vacancy is thermodynamic stability in bulk GaN. The thermodynamic stability of the GaN with the N-vacancy is demonstrated by the change of Ga N bond. Three GaN show the semiconductor feature because of the role of N-2p state. The calculated band gap of GaN with the P63mc, F-43m and Fm-3m is 1.651, 1.489 and 0.450 eV. However, the N-vacancy enhances the electronic jump of GaN because the N-vacancy induces the move of the position of Fermi level to the region of the conduction band. The metallic behavior of GaN with the N-vacancy is demonstrated by the dielectric function diagram. In particular, the N-vacancy gives rise to the visible light region optical adsorption compared to the corresponding bulk GaN.

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Thermal management and packaging of wide and ultra-wide bandgap power devices: a review and perspective

Qin

Albano

Spencer

et al. 2023

J. Phys. D: Appl. Phys.

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Power semiconductor device is a fundamental driver for advancement in power electronics, the technology for electric energy conversion. Power devices based on wide-bandgap (WBG) and ultra-wide bandgap (UWBG) semiconductors allow for smaller chip size, lower loss and higher frequency as compared to the silicon (Si) counterpart, thus enabling a higher system efficiency and smaller form factor. Amongst the challenges for the development and deployment of WBG and UWBG devices is the efficient dissipation of heat, an unavoidable by-product of the higher power density. To mitigate the performance limitations and reliability issues caused by self-heating, thermal management is required at both device and package levels. Particularly, packaging is a crucial milestone for the development of any power device technology; WBG and UWBG devices have both reached this milestone recently. This paper provides a timely review on the thermal management of WBG and UWBG power devices with an emphasis on the packaged devices. Additionally, emerging UWBG devices hold good promise for high-temperature applications due to the low intrinsic carrier density and the increased dopant ionization at elevated temperatures. The fulfillment of this promise in system applications, in conjunction with overcoming the thermal limitations of some UWBG materials, require new thermal management and packaging technologies. To this end, we provide perspectives on the relevant challenges, potential solutions and research opportunities, highlighting the pressing needs for the device-package, electro-thermal co-design and the high-temperature packages that can withstand the high electric field expected in UWBG devices.

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Semi-insulating GaN for vertical structures: role of substrate selection and growth pressure

Cited by 7 publications

References 18 publications

Vertical GaN Transistor with Semi‐Insulating Channel

Vertical GaN Transistor with Semi‐Insulating Channel

Influence of N‐vacancy on the electronic and optical properties of bulk GaN from first‐principles investigations

Thermal management and packaging of wide and ultra-wide bandgap power devices: a review and perspective

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