Vertical 3D gallium nitride field-effect transistors based on fin structures with inverted p-doped channel

Publikation: Beitrag in FachzeitschriftArtikelForschungPeer-Review

Autoren

  • Klaas Strempel
  • Friedhard Römer
  • Feng Yu
  • Matteo Meneghini
  • Andrey Bakin
  • Hergo Heinrich Wehmann
  • Bernd Witzigmann
  • Andreas Waag

Externe Organisationen

  • Technische Universität Braunschweig
  • Universität Kassel
  • Università degli Studi di Padova
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Details

OriginalspracheEnglisch
Aufsatznummer014002
FachzeitschriftSemiconductor Science and Technology
Jahrgang36
Ausgabenummer1
Frühes Online-Datum29 Okt. 2020
PublikationsstatusVeröffentlicht - Jan. 2021
Extern publiziertJa

Abstract

This paper demonstrates the first vertical field-effect transistor based on gallium nitride (GaN) fin structures with an inverted p-doped channel layer. A top-down hybrid etching approach combining inductively coupled plasma reactive ion etching and KOH-based wet etching was applied to fabricate regular fields of GaN fins with smooth a-plane sidewalls. The obtained morphologies are explained using a cavity step-flow model. A 3D processing scheme has been developed and evaluated via focussed ion beam cross-sections. The top-down approach allows the introduction of arbitrary doping profiles along the channel without regrowth, enabling the modulation of the channel properties and thus increasing the flexibility of the device concept. Here, a vertical npn-doping profile was used to achieve normally-off operation with an increased threshold voltage as high as 2.65 V. The p-doped region and the 3D gate wrapped around the sidewalls create a very narrow vertical electron channel close to the interface between dielectric and semiconductor, resulting in good electrostatic gate control, low leakage currents through the inner fin core and high sensitivity to the interface between GaN and gate oxide. Hydrodynamic transport simulations were carried out and show good agreement with the performed current-voltage and capacitance-voltage measurements. The simulation indicates a reduced channel mobility which we attribute to interface scattering being particularly relevant in narrow channels. We also demonstrate the existence of oxide and interface traps with an estimated sheet density of 3.2 × 1012 cm-2 related to the Al2O3 gate dielectric causing an increased subthreshold swing. Thus, improving the interface quality is essential to reach the full potential of the presented vertical 3D transistor concept.

ASJC Scopus Sachgebiete

Zitieren

Vertical 3D gallium nitride field-effect transistors based on fin structures with inverted p-doped channel. / Strempel, Klaas; Römer, Friedhard; Yu, Feng et al.
in: Semiconductor Science and Technology, Jahrgang 36, Nr. 1, 014002, 01.2021.

Publikation: Beitrag in FachzeitschriftArtikelForschungPeer-Review

Strempel, K, Römer, F, Yu, F, Meneghini, M, Bakin, A, Wehmann, HH, Witzigmann, B & Waag, A 2021, 'Vertical 3D gallium nitride field-effect transistors based on fin structures with inverted p-doped channel', Semiconductor Science and Technology, Jg. 36, Nr. 1, 014002. https://doi.org/10.1088/1361-6641/abc5ff
Strempel, K., Römer, F., Yu, F., Meneghini, M., Bakin, A., Wehmann, H. H., Witzigmann, B., & Waag, A. (2021). Vertical 3D gallium nitride field-effect transistors based on fin structures with inverted p-doped channel. Semiconductor Science and Technology, 36(1), Artikel 014002. https://doi.org/10.1088/1361-6641/abc5ff
Strempel K, Römer F, Yu F, Meneghini M, Bakin A, Wehmann HH et al. Vertical 3D gallium nitride field-effect transistors based on fin structures with inverted p-doped channel. Semiconductor Science and Technology. 2021 Jan;36(1):014002. Epub 2020 Okt 29. doi: 10.1088/1361-6641/abc5ff
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title = "Vertical 3D gallium nitride field-effect transistors based on fin structures with inverted p-doped channel",
abstract = "This paper demonstrates the first vertical field-effect transistor based on gallium nitride (GaN) fin structures with an inverted p-doped channel layer. A top-down hybrid etching approach combining inductively coupled plasma reactive ion etching and KOH-based wet etching was applied to fabricate regular fields of GaN fins with smooth a-plane sidewalls. The obtained morphologies are explained using a cavity step-flow model. A 3D processing scheme has been developed and evaluated via focussed ion beam cross-sections. The top-down approach allows the introduction of arbitrary doping profiles along the channel without regrowth, enabling the modulation of the channel properties and thus increasing the flexibility of the device concept. Here, a vertical npn-doping profile was used to achieve normally-off operation with an increased threshold voltage as high as 2.65 V. The p-doped region and the 3D gate wrapped around the sidewalls create a very narrow vertical electron channel close to the interface between dielectric and semiconductor, resulting in good electrostatic gate control, low leakage currents through the inner fin core and high sensitivity to the interface between GaN and gate oxide. Hydrodynamic transport simulations were carried out and show good agreement with the performed current-voltage and capacitance-voltage measurements. The simulation indicates a reduced channel mobility which we attribute to interface scattering being particularly relevant in narrow channels. We also demonstrate the existence of oxide and interface traps with an estimated sheet density of 3.2 × 1012 cm-2 related to the Al2O3 gate dielectric causing an increased subthreshold swing. Thus, improving the interface quality is essential to reach the full potential of the presented vertical 3D transistor concept.",
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note = "Acknowledgments This work was funded by the Deutsche Forschungsgesellschaft (DFG, German Research Formation) within the project {\textquoteleft}3D Concepts for Gallium Nitride Electroncis{\textquoteright}— 284575374 and under Germany{\textquoteright}s Excellence Strategy—EXC- 2123 Quantum Frontiers—390837967. The authors thank I. Manglano Clavero and C. Margenfeld for wafer growth in the Epitaxy Competence Center (ec2), a joint venture by the Institute of Semiconductor Technology and OSRAM Opto Semiconductors. We gratefully acknowledge the technical assistance of Juliane Breitfelder, Diana Herz and Angelika Schmidt.",
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T1 - Vertical 3D gallium nitride field-effect transistors based on fin structures with inverted p-doped channel

AU - Strempel, Klaas

AU - Römer, Friedhard

AU - Yu, Feng

AU - Meneghini, Matteo

AU - Bakin, Andrey

AU - Wehmann, Hergo Heinrich

AU - Witzigmann, Bernd

AU - Waag, Andreas

N1 - Acknowledgments This work was funded by the Deutsche Forschungsgesellschaft (DFG, German Research Formation) within the project ‘3D Concepts for Gallium Nitride Electroncis’— 284575374 and under Germany’s Excellence Strategy—EXC- 2123 Quantum Frontiers—390837967. The authors thank I. Manglano Clavero and C. Margenfeld for wafer growth in the Epitaxy Competence Center (ec2), a joint venture by the Institute of Semiconductor Technology and OSRAM Opto Semiconductors. We gratefully acknowledge the technical assistance of Juliane Breitfelder, Diana Herz and Angelika Schmidt.

PY - 2021/1

Y1 - 2021/1

N2 - This paper demonstrates the first vertical field-effect transistor based on gallium nitride (GaN) fin structures with an inverted p-doped channel layer. A top-down hybrid etching approach combining inductively coupled plasma reactive ion etching and KOH-based wet etching was applied to fabricate regular fields of GaN fins with smooth a-plane sidewalls. The obtained morphologies are explained using a cavity step-flow model. A 3D processing scheme has been developed and evaluated via focussed ion beam cross-sections. The top-down approach allows the introduction of arbitrary doping profiles along the channel without regrowth, enabling the modulation of the channel properties and thus increasing the flexibility of the device concept. Here, a vertical npn-doping profile was used to achieve normally-off operation with an increased threshold voltage as high as 2.65 V. The p-doped region and the 3D gate wrapped around the sidewalls create a very narrow vertical electron channel close to the interface between dielectric and semiconductor, resulting in good electrostatic gate control, low leakage currents through the inner fin core and high sensitivity to the interface between GaN and gate oxide. Hydrodynamic transport simulations were carried out and show good agreement with the performed current-voltage and capacitance-voltage measurements. The simulation indicates a reduced channel mobility which we attribute to interface scattering being particularly relevant in narrow channels. We also demonstrate the existence of oxide and interface traps with an estimated sheet density of 3.2 × 1012 cm-2 related to the Al2O3 gate dielectric causing an increased subthreshold swing. Thus, improving the interface quality is essential to reach the full potential of the presented vertical 3D transistor concept.

AB - This paper demonstrates the first vertical field-effect transistor based on gallium nitride (GaN) fin structures with an inverted p-doped channel layer. A top-down hybrid etching approach combining inductively coupled plasma reactive ion etching and KOH-based wet etching was applied to fabricate regular fields of GaN fins with smooth a-plane sidewalls. The obtained morphologies are explained using a cavity step-flow model. A 3D processing scheme has been developed and evaluated via focussed ion beam cross-sections. The top-down approach allows the introduction of arbitrary doping profiles along the channel without regrowth, enabling the modulation of the channel properties and thus increasing the flexibility of the device concept. Here, a vertical npn-doping profile was used to achieve normally-off operation with an increased threshold voltage as high as 2.65 V. The p-doped region and the 3D gate wrapped around the sidewalls create a very narrow vertical electron channel close to the interface between dielectric and semiconductor, resulting in good electrostatic gate control, low leakage currents through the inner fin core and high sensitivity to the interface between GaN and gate oxide. Hydrodynamic transport simulations were carried out and show good agreement with the performed current-voltage and capacitance-voltage measurements. The simulation indicates a reduced channel mobility which we attribute to interface scattering being particularly relevant in narrow channels. We also demonstrate the existence of oxide and interface traps with an estimated sheet density of 3.2 × 1012 cm-2 related to the Al2O3 gate dielectric causing an increased subthreshold swing. Thus, improving the interface quality is essential to reach the full potential of the presented vertical 3D transistor concept.

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