In:
ECS Meeting Abstracts, The Electrochemical Society, Vol. MA2019-01, No. 26 ( 2019-05-01), p. 1266-1266
Abstract:
β-Ga 2 O 3 is an intriguing material for high efficiency power devices because of its large direct bandgap (4.85 eV), high breakdown field (~8 MV/cm) and excellent thermal and chemical stability. Baliga’s figure of merit of β-Ga 2 O 3 is 3214.1, superior to those of other materials such as GaN (846.0) or SiC (317.1). Interestingly, although β-Ga 2 O 3 is not a van der Waals material, β-Ga 2 O 3 can be mechanically exfoliated from single crystal substrate into thin layer due to the large anisotropy of the unit cell. The fabrication of high crystal quality β-Ga 2 O 3 nanolayer devices could pave a way for next-generation high-power nanoelectronics devices. In power device operation, the premature electrical induced by the concentrated electric fields limits the device operation under a high bias voltage, and threaten the reliability of devices. Various techniques such as recess gate or field-plate configurations have been proposed to relieve the electric field concentration and prevent premature breakdown. Adopting gate field plate, source field plate, or multiple field plate greatly enhance the performance of power devices, which can be applied to β-Ga 2 O 3 based nanoelectronic power devices that can unlock the full potential of β-Ga 2 O 3 . Due to the exceptional mechanical and electronic properties of 2D materials, researches about 2D materials has been at the forefront of this area during the last years. Studies on fabrication of functional devices based on 2D materials, including integration with themselves, are exploding. Among 2D materials, hexagonal boron nitride (h-BN) has been used as a dielectric material of 2D devices due to its excellent thermal conduc tivity (1700 – 2000 W/m∙K) and high dielectric constant (8 – 12 MV/cm), as well as defect-free and atomically flat surface, which can easily be obtained through mechanical exfoliation method. In our work, we used h-BN as a gate field plate dielectric layer by precise and selective transfer on β-Ga 2 O 3 channel by using PDMS film. SiO 2 dielectric layer was deposited on devices, followed by metal deposition for source field plate. By applying dual field plate structure β-Ga 2 O 3 based power devices can show excellent performance in high voltage condition than conventional metal-semiconductor field effect transistors (MESFETs). β-Ga 2 O 3 MESFETs with h-BN gate field plate were fabricated by using the β-Ga 2 O 3 and h-BN flakes obtained from respective crystals. Ohmic metal (Ti/Au) was deposited on both end of mechanically exfoliated β-Ga 2 O 3 flakes, followed by precise positioning of exfoliated h-BN flakes on the channel. Top-gate electrode (Ni/Au) was deposited to fabricate β-Ga 2 O 3 MESFETs, with a part of the electrode overlapped with h-BN to achieve a stepped gate field-plate structure. After deposition of SiO 2 layer as dielectric layer of source field plate, selective etching of SiO 2 layer was performed to construct source field plate structure. Fabricated β-Ga 2 O 3 MESFETs showed excellent n-type DC output and transfer characteristics even after storage for one month in ambient air, which shows excellent long-term air-stability. Three-terminal off-state breakdown voltage of dual field-plated β-Ga 2 O 3 MESFET was measured, which shows improvement in breakdown voltage compared with that of conventional β-Ga 2 O 3 MESFET. The distribution of electric fields was calculated by Silvaco Atlas device simulation framework to study the effect of source field plate and h-BN gate field plate on electric field, which explain the improvement of breakdown voltage in those structure. By adopting dual field plate structure, ease of distribution of concentrated electric field was observed. In this study, we present that the performance of β-Ga 2 O 3 MESFET as a power device can be greatly improved by adopting dual field plate structure, paving a way to the high-power nanoelectronic devices of β-Ga 2 O 3 . The details of our work will be discussed in the conference.
Type of Medium:
Online Resource
ISSN:
2151-2043
DOI:
10.1149/MA2019-01/26/1266
Language:
Unknown
Publisher:
The Electrochemical Society
Publication Date:
2019
detail.hit.zdb_id:
2438749-6
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