| 1. |
- Zhang, Hongpeng, et al.
(författare)
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Influence of Metal Gate Electrodes on Electrical Properties of Atomic-Layer-Deposited Al-Rich HfAlO/Ga2O3 MOSCAPs
- 2020
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Ingår i: IEEE Transactions on Electron Devices. - : IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC. - 0018-9383 .- 1557-9646. ; 67:4, s. 1730-1736
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Tidskriftsartikel (refereegranskat)abstract
- As the p-type doping beta-Ga2O3 is absent up to now, metal gate (MG) stacks with high work functions are expected to benefit the fabrication of normally-OFF beta-Ga2O3 transistors. In this article, the electrical characteristics of beta-Ga2O3 metal-electrode-gated metal-oxidesemiconductor (MOS) deviceswith Al-rich HfAlO dielectrics and different MG stacks (Ni, Au, Pt, and Ti) are evaluated. The interface state density (Dit) of HfAlO/ beta-Ga2O3 interface is characterized based on the frequency-dependent capacitance-voltage (C-V) and photo-assisted deep ultraviolet (DUV) C-V measurements. An average Dit of 4.45 x 10(11) eV(-1)cm(-2) is extracted from the photo-assisted (deep UV) C-V measurement, while a large amount of border traps, negative fixed charges, and deep traps is also induced at the oxide layer and/or HfAlO/beta-Ga2O3 interface. Then, this article investigates the evaluations of Ti, Ni, Au, and Pt as candidate MGs for beta-Ga2O3 MOS using Al-rich HfAlO as gate dielectric. The obvious flat-band voltage (V-FB) shift and gate leakage variation are observed in beta-Ga2O3 capacitors with different MG solutions, indicating that HfAlO dielectric combined with Ni, Au, and Pt MGs is promising to facilitate some beneficial modifications of normally-OFF beta-Ga2O3 transistors, while Ti electrode ismore suitable for normally-ON beta-Ga2O3 transistors. This article provides an additional practical guideline for choosing the appropriate MG stacks and potential gate dielectric to the development of normally-OFF Ga2O3 transistors.
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| 2. |
- Zhang, Hongpeng, et al.
(författare)
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Progress of Ultra-Wide Bandgap Ga < sub > 2 O < sub > 3 Semiconductor Materials in Power MOSFETs
- 2020
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Ingår i: IEEE transactions on power electronics. - : IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC. - 0885-8993 .- 1941-0107. ; 35:5, s. 5157-5179
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Tidskriftsartikel (refereegranskat)abstract
- As a promising ultra-wide bandgap semiconductor, the <italic>& x03B2;</italic>-phase of Ga<sub>2</sub>O<sub>3</sub> has attracted more and more interest in the field of power electronics due to its ultra-wide bandgap (4.8 & x00A0;eV), high theoretical breakdown electric field (8 MV & x002F;cm), and large Baliga & x0027;s figure of merit, which is deemed as a potential candidate for next generation high-power electronics, including diodes, field effect transistors (FETs), etc. In this article, we introduce the basic material properties of Ga<sub>2</sub>O<sub>3</sub>, and review the recent progress and advances of <italic>& x03B2;</italic>-Ga<sub>2</sub>O<sub>3</sub> based metal & x2013;oxide & x2013;semiconductor field-effect transistors (<sc>mosfet</sc>s). Due to the problematic p-type doping technology up to now, the enhancement-mode (E-mode) <italic>& x03B2;</italic>-Ga<sub>2</sub>O<sub>3</sub> FETs face more difficulties, compared with depletion mode (D-mode). This article focuses on reviewing the recent progress of E-mode Ga<sub>2</sub>O<sub>3</sub> <sc>mosfet</sc>s, summarizing and comparing various feasible solutions when p-type doping is absent. Furthermore, the device fabrication and performances of state-of-art <italic>& x03B2;</italic>-Ga<sub>2</sub>O<sub>3</sub> <sc>mosfet</sc>s, including D-mode, E-mode, and planar & x002F;vertical structure are fully discussed and compared, as well as potential solutions to the challenges of Ga<sub>2</sub>O<sub>3</sub> FETs.
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| 3. |
- Zhang, Hongpeng, et al.
(författare)
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Stress-induced charge trapping and electrical properties of atomic-layer-deposited HfAlO/Ga2O3 metal-oxide-semiconductor capacitors
- 2019
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Ingår i: Journal of Physics D. - : IOP PUBLISHING LTD. - 0022-3727 .- 1361-6463. ; 52:21
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Tidskriftsartikel (refereegranskat)abstract
- Electrical properties and trapping characteristics of an atomic layer deposited Al-rich HfAlO/beta-Ga2O3 capacitor were evaluated via constant-voltage stress (CVS), capacitance-voltage (C-V), and current-voltage (I-V) measurements. The magnitude of the stress-induced charge trapping increases with increasing voltage and time. The effective charges (N-eff) including the border traps located in near-interface oxide, interface traps (D-it) of HfAlO/beta-Ga2O3 interface, and fixed charges contribute significantly to the observed charge trapping, and it is found that interface traps contribute more under a large stress bias, compared with border traps. In addition, the effective charge density is increased with stress time, implying that the contribution of negative sheet charges during the CVS process might not be negligible. Measurements of oxide permittivity (10.74), interface state density (D-it similar to 1 x 10(12) eV(-1) cm(-2)), and gate leakage current (1.18 x 10( -5) A cm(-2) at +10 V) have been extracted, suggesting the great electrical properties of Al-rich HfAlO/beta-Ga203 MOSCAP. According to the above analysis, Al-rich HfAlO is an attractive candidate for normally off Ga2O3 transistors.
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