Effect of GaN surface treatment on Al2O3/ n -GaN MOS capacitors

Tashfin Hossain; Daming Wei; James H. Edgar; Nelson Y. Garces; Neeraj Nepal; Jennifer K. Hite; Michael A. Mastro; Charles R. Eddy; Harry M. Meyer

doi:10.1116/1.4931793

Effect of GaN surface treatment on Al₂O₃/ n -GaN MOS capacitors

Tashfin Hossain, Daming Wei, James H. Edgar, Nelson Y. Garces, Neeraj Nepal, Jennifer K. Hite, Michael A. Mastro, Charles R. Eddy, Harry M. Meyer

Surface Chemistry & Catalysis Group

Research output: Contribution to journal › Article › peer-review

39 Scopus citations

Abstract

The surface preparation for depositing Al₂O₃ for fabricating Au/Ni/Al₂O₃/n-GaN (0001) metal oxide semiconductor (MOS) capacitors was optimized as a step toward realization of high performance GaN MOSFETs. The GaN surface treatments studied included cleaning with piranha (H₂O₂:H₂SO₄ = 1:5), (NH₄)₂S, and 30% HF etches. By several metrics, the MOS capacitor with the piranha-etched GaN had the best characteristics. It had the lowest capacitance-voltage hysteresis, the smoothest Al₂O₃ surface as determined by atomic force microscopy (0.2 nm surface roughness), the lowest carbon concentration (∼0.78%) at the Al₂O₃/n-GaN interface (from x-ray photoelectron spectroscopy), and the lowest oxide-trap charge (Q_T = 1.6 × 10¹¹cm^-2eV^-1). Its interface trap density (D_it = 3.7 × 10¹²cm^-2eV^-1), as measured with photon-assisted capacitance- voltage method, was the lowest from conduction band-edge to midgap.

Original language	English
Article number	061201
Journal	Journal of Vacuum Science and Technology B: Nanotechnology and Microelectronics
Volume	33
Issue number	6
DOIs	https://doi.org/10.1116/1.4931793
State	Published - Nov 1 2015

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title = "Effect of GaN surface treatment on Al2O3/ n -GaN MOS capacitors",

abstract = "The surface preparation for depositing Al2O3 for fabricating Au/Ni/Al2O3/n-GaN (0001) metal oxide semiconductor (MOS) capacitors was optimized as a step toward realization of high performance GaN MOSFETs. The GaN surface treatments studied included cleaning with piranha (H2O2:H2SO4 = 1:5), (NH4)2S, and 30% HF etches. By several metrics, the MOS capacitor with the piranha-etched GaN had the best characteristics. It had the lowest capacitance-voltage hysteresis, the smoothest Al2O3 surface as determined by atomic force microscopy (0.2 nm surface roughness), the lowest carbon concentration (∼0.78%) at the Al2O3/n-GaN interface (from x-ray photoelectron spectroscopy), and the lowest oxide-trap charge (QT = 1.6 × 1011cm-2eV-1). Its interface trap density (Dit = 3.7 × 1012cm-2eV-1), as measured with photon-assisted capacitance- voltage method, was the lowest from conduction band-edge to midgap.",

author = "Tashfin Hossain and Daming Wei and Edgar, {James H.} and Garces, {Nelson Y.} and Neeraj Nepal and Hite, {Jennifer K.} and Mastro, {Michael A.} and Eddy, {Charles R.} and Meyer, {Harry M.}",

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AU - Hossain, Tashfin

AU - Wei, Daming

AU - Edgar, James H.

AU - Garces, Nelson Y.

AU - Nepal, Neeraj

AU - Hite, Jennifer K.

AU - Mastro, Michael A.

AU - Eddy, Charles R.

AU - Meyer, Harry M.

PY - 2015/11/1

Y1 - 2015/11/1

N2 - The surface preparation for depositing Al2O3 for fabricating Au/Ni/Al2O3/n-GaN (0001) metal oxide semiconductor (MOS) capacitors was optimized as a step toward realization of high performance GaN MOSFETs. The GaN surface treatments studied included cleaning with piranha (H2O2:H2SO4 = 1:5), (NH4)2S, and 30% HF etches. By several metrics, the MOS capacitor with the piranha-etched GaN had the best characteristics. It had the lowest capacitance-voltage hysteresis, the smoothest Al2O3 surface as determined by atomic force microscopy (0.2 nm surface roughness), the lowest carbon concentration (∼0.78%) at the Al2O3/n-GaN interface (from x-ray photoelectron spectroscopy), and the lowest oxide-trap charge (QT = 1.6 × 1011cm-2eV-1). Its interface trap density (Dit = 3.7 × 1012cm-2eV-1), as measured with photon-assisted capacitance- voltage method, was the lowest from conduction band-edge to midgap.

AB - The surface preparation for depositing Al2O3 for fabricating Au/Ni/Al2O3/n-GaN (0001) metal oxide semiconductor (MOS) capacitors was optimized as a step toward realization of high performance GaN MOSFETs. The GaN surface treatments studied included cleaning with piranha (H2O2:H2SO4 = 1:5), (NH4)2S, and 30% HF etches. By several metrics, the MOS capacitor with the piranha-etched GaN had the best characteristics. It had the lowest capacitance-voltage hysteresis, the smoothest Al2O3 surface as determined by atomic force microscopy (0.2 nm surface roughness), the lowest carbon concentration (∼0.78%) at the Al2O3/n-GaN interface (from x-ray photoelectron spectroscopy), and the lowest oxide-trap charge (QT = 1.6 × 1011cm-2eV-1). Its interface trap density (Dit = 3.7 × 1012cm-2eV-1), as measured with photon-assisted capacitance- voltage method, was the lowest from conduction band-edge to midgap.

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Effect of GaN surface treatment on Al₂O₃/ n -GaN MOS capacitors

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