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Abstract In this work, TiO2thin films deposited by the atomic layer deposition (ALD) method were treated with a special N2O plasma surface treatment and used as the gate dielectric for AlGaN/GaN metal insulator semiconductor high electron mobility transistors (MISHEMTs). The N2O plasma surface treatment effectively reduces defects in the oxide during low-temperature ALD growth. In addition, it allows oxygen atoms to diffuse into the device cap layer to increase the barrier height and thus reduce the gate leakage current. These TiO2films exhibit a dielectric constant of 54.8 and a two-terminal current of 1.96 × 10−10A mm−1in 2μm distance. When applied as the gate dielectric, the AlGaN/GaN MISHEMT with a 2μm-gate-length shows a high on/off ratio of 2.59 × 108and a low subthreshold slope (SS) of 84 mV dec−1among all GaN MISHEMTs using TiO2as the gate dielectric. This work provides a feasible way to significantly improve the TiO2film electrical property for gate dielectrics, and it suggests that the developed TiO2dielectric is a promising high-κgate oxide and a potential passivation layer for GaN-based MISHEMTs, which can be further extended to other transistors.
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Ultrawide bandgap Al x Ga 1-x N channel heterostructure field transistors with drain currents exceeding 1.3 A/mm
We report an Ultrawide Bandgap Al0.4Ga0.6N channel Metal-Oxide-Semiconductor Heterostructure field effect transistor with drain currents exceeding 1.33 A/mm (pulse) and 1.17A/mm (DC), around 2-fold increase over reported for AlGaN HFETs. The increase was achieved by incorporating hybrid barrier layer consisting of an AlN spacer, n-doped Al0.6Ga0.4N barrier and a thin reverse graded AlxGa1-xN (x from 0.60 to 0.30) cap layer. To enhance current spreading, a "perforated" channel layout comprising of narrow channel sections separated by current blocking islands was used. A composite ALD deposited ZrO2/Al2O3 film was used as gate dielectric. A breakdown field above 2MV/cm was measured.
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- PAR ID:
- 10188502
- Date Published:
- Journal Name:
- Applied Physics Express
- ISSN:
- 1882-0778
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.35848/1882-0786/abb1c8
