Oxygen atom ordering on SiO2/4H-SiC {0001} polar interfaces formed by wet oxidation

Saito, Mitsuhiro; Li, Hongping; Inoue, Kazutoshi; Matsuhata, Hirofumi; Ikuhara, Yuichi

doi:10.1016/j.actamat.2021.117360

Cited by 6 publications

(3 citation statements)

References 31 publications

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“…Considering the high-intensity O element around the interface shown in Figure , we believe the trilayer is an oxide layer. According to M. Saito’s calculation, the strong O–Si bond predisposed the Si-terminated SiC surface to be reconstructed with a thin and flat oxidation front . In our experiment, the Si-terminated surface of 4H–SiC is inevitable to be oxidized during the air-exposed wafer pre-loading process and concurrent vacuumizing/substrate heating processes before starting sputtering.…”

Section: Resultsmentioning

confidence: 68%

“…According to M. Saito's calculation, the strong O−Si bond predisposed the Si-terminated SiC surface to be reconstructed with a thin and flat oxidation front. 35 In our experiment, the Si-terminated surface of 4H−SiC is inevitable to be oxidized during the air-exposed wafer preloading process and concurrent vacuumizing/substrate heating processes before starting sputtering. The possible atomic model around the AlN/SiC interface is proposed based on the STEM images.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

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Unexpected Realization of N-Polar AlN Films on Si-Face 4H–SiC Substrates Using RF Sputtering and High-Temperature Annealing

Zhang

Guo

Cai

et al. 2023

Crystal Growth & Design

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In this study, we demonstrated AlN films with unexpected N-polarity on Si-face 4H−SiC substrates using RF reactive magnetron sputtering and post high-temperature annealing (HTA). It is found that HTA-AlN sputtered with pure nitrogen or mixed gases of nitrogen and trace oxygen exhibits undoubtable N polarity, which appears to contradict the common assumption of Al-polar AlN on Si-face SiC. The interfacial studies of HTA-AlN sputtered with pure N 2 reveal that the naturally oxidized SiC surface induces the formation of Si−O�Al−N bonds rather than conventional Si�N−Al bonds, thereby causing N-polar AlN. Sputtering with the mixed gases results in 5 nm thick complex transition layers at the AlN/SiC interface, including two types of oxygen-participated energy-unstable inversion domain boundaries and multiple polarity inverted AlN layers. Compared to that sputtered with the mixed gases, the N-polar HTA-AlN film sputtered with pure nitrogen presents a smoother surface morphology for the absence of AlON islands and lower threading dislocation density due to closer X-ray rocking curve full widths at half-maximum for (0002) and (101̅ 2) reflections. This work proves a new approach to prepare high-quality N-polar AlN/SiC templates for Al-rich AlGaN-based N-polar optoelectronic and power devices.

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Section: Resultsmentioning

confidence: 68%

Section: ■ Results and Discussionmentioning

confidence: 99%

Unexpected Realization of N-Polar AlN Films on Si-Face 4H–SiC Substrates Using RF Sputtering and High-Temperature Annealing

Zhang

Guo

Cai

et al. 2023

Crystal Growth & Design

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show abstract

“…The interface trap states are generated during the formation of the gate oxide film, produced via thermal oxidation of SiC in pure oxygen (dry oxidation) or in oxygen with the addition of water vapor (wet oxidation). Different types of defects are observed in the oxide film depending on temperature and oxidation time, the SiC crystal surface’s orientation, and chemical treatments of the surface before and during the oxidation process [ 12 , 13 , 14 , 15 ]. A major source of defects responsible for electrically active trap centers, especially those close to the conduction band edge, are various carbon-related defects such as carbon dimmers and carbon interstitials, as revealed by Density Functional Theory (DFT) simulations [ 16 , 17 , 18 ].…”

Section: Introductionmentioning

confidence: 99%

Carrier Trap Density Reduction at SiO2/4H-Silicon Carbide Interface with Annealing Processes in Phosphoryl Chloride and Nitride Oxide Atmospheres

et al. 2023

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The electrical and physical properties of the SiC/SiO2 interfaces are critical for the reliability and performance of SiC-based MOSFETs. Optimizing the oxidation and post-oxidation processes is the most promising method of improving oxide quality, channel mobility, and thus the series resistance of the MOSFET. In this work, we analyze the effects of the POCl3 annealing and NO annealing processes on the electrical properties of metal–oxide–semiconductor (MOS) devices formed on 4H-SiC (0001). It is shown that combined annealing processes can result in both low interface trap density (Dit), which is crucial for oxide application in SiC power electronics, and high dielectric breakdown voltage comparable with those obtained via thermal oxidation in pure O2. Comparative results of non-annealed, NO-annealed, and POCl3-annealed oxide–semiconductor structures are shown. POCl3 annealing reduces the interface state density more effectively than the well-established NO annealing processes. The result of 2 × 1011 cm−2 for the interface trap density was attained for a sequence of the two-step annealing process in POCl3 and next in NO atmospheres. The obtained values Dit are comparable to the best results for the SiO2/4H-SiC structures recognized in the literature, while the dielectric critical field was measured at a level ≥9 MVcm−1 with low leakage currents at high fields. Dielectrics, which were developed in this study, have been used to fabricate the 4H-SiC MOSFET transistors successfully.

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Improved 4H-SiC Metal–Semiconductor Field-Effect Transistors with Double-Symmetric-Step Buried Oxide Layer for High-Energy-Efficiency Applications

Zhu

Jia

Dong

et al. 2022

J. Electron. Mater.

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Oxygen atom ordering on SiO2/4H-SiC {0001} polar interfaces formed by wet oxidation

Cited by 6 publications

References 31 publications

Unexpected Realization of N-Polar AlN Films on Si-Face 4H–SiC Substrates Using RF Sputtering and High-Temperature Annealing

Unexpected Realization of N-Polar AlN Films on Si-Face 4H–SiC Substrates Using RF Sputtering and High-Temperature Annealing

Carrier Trap Density Reduction at SiO2/4H-Silicon Carbide Interface with Annealing Processes in Phosphoryl Chloride and Nitride Oxide Atmospheres

Improved 4H-SiC Metal–Semiconductor Field-Effect Transistors with Double-Symmetric-Step Buried Oxide Layer for High-Energy-Efficiency Applications

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