Improvements of electronic and optical characteristics of n-GaN-based structures by photoelectrochemical oxidation in glycol solution

Shiozaki, Nanako; Hashizume, Tamotsu

doi:10.1063/1.3079502

Cited by 14 publications

(10 citation statements)

References 45 publications

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“…The insert in Figure shows O 1s and Ga 3d XPS spectra. The O 1s peak at 531.3 eV is attributed to chemisorbed oxygen and the Ga 3d core level yields peak positions at 20.6 to 20.8 eV for Ga–O bonding and 19.6 to 19.8 eV for Ga–N bonding. , Therefore, the Ga 3d peak at 19.8 eV can be assigned to nitride. The O 1s and Ga 3d peaks confirm that the samples are gallium nitride and not oxide.…”

Section: Resultsmentioning

confidence: 99%

Crystallization Effects of Nanocrystalline GaN Films on Field Emission

Zhao

Wang

et al. 2013

J. Phys. Chem. C

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Nanocrystalline GaN films are fabricated on Si substrates by pulsed laser deposition to achieve enhanced field emission (FE) based on microstructural engineering. In the process, the microstructure including crystallization and orientation can be conveniently and directly modulated by the temperature. XRD reveals that the fabrication temperature affects the crystallinity and grain size of the GaN films. A strong correlation between the microstructure and FE properties is also observed. The turn-on electric field decreases from 30.5 to 2.3 V/μm, and the FE current density increases by two to three orders of magnitude based on the microstructure of the GaN films. A qualitative grain boundary conduction model is proposed to explain the strong correlation between the microstructure and FE properties. The results demonstrate the importance of microstructural effects on FE, and they must be considered in the design and production of FE GaN devices.

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Section: Resultsmentioning

confidence: 99%

Crystallization Effects of Nanocrystalline GaN Films on Field Emission

Zhao

Wang

et al. 2013

J. Phys. Chem. C

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“…28 The broader linewidth and the chemical shift of Ga Auger signal were also observed in the GaO x layer prepared by photoelectrochemical oxidation of GaN. 29 That is, the XPS spectra obtained from the N 2 O-radical treated surface contain those of the AlGaN and AlGa-oxide layers, suggesting the oxidation layer was very thin (1 nm or less). Bae et al 30 reported that an ultra thin Ga-oxide layer prepared by the remote plasma-assisted oxidation process is effective in reducing interface states for the SiO 2 /n-GaN system.…”

Section: B Chemical Properties Of N 2 O-radical Treated Algan Surfacementioning

confidence: 99%

Characterization of interface states in Al2O3/AlGaN/GaN structures for improved performance of high-electron-mobility transistors

Hori¹,

Yatabe²,

Hashizume³

2013

Journal of Applied Physics

155

120

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We have investigated the relationship between improved electrical properties of Al 2 O 3 /AlGaN/GaN metal-oxide-semiconductor high-electron-mobility transistors (MOS-HEMTs) and electronic state densities at the Al 2 O 3 /AlGaN interface evaluated from the same structures as the MOS-HEMTs. To evaluate Al 2 O 3 /AlGaN interface state densities of the MOS-HEMTs, two types of capacitance-voltage (C-V) measurement techniques were employed: the photo-assisted C-V measurement for the near-midgap states and the frequency dependent C-V characteristics for the states near the conduction-band edge. To reduce the interface states, an N 2 O-radical treatment was applied to the AlGaN surface just prior to the deposition of the Al 2 O 3 insulator. As compared to the sample without the treatment, the N 2 O-radical treated Al 2 O 3 /AlGaN/GaN structure showed smaller frequency dispersion of the C-V curves in the positive gate bias range. The state densities at the Al 2 O 3 /AlGaN interface were estimated to be 1 Â 10 12 cm À2 eV À1 or less around the midgap and 8 Â 10 12 cm À2 eV À1 near the conduction-band edge. In addition, we observed higher maximum drain current at the positive gate bias and suppressed threshold voltage instability under the negative gate bias stress even at 150 C. Results presented in this paper indicated that the N 2 O-radical treatment is effective both in reducing the interface states and improving the electrical properties of the Al 2 O 3 /AlGaN/GaN MOS-HEMTs. V C 2013 AIP Publishing LLC. [http://dx

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“…Fig. 7 compares the O 1s core-level spectra of the HPWV-annealed and reference samples taken with a photoelectron escape angle of 45°, corresponding to a probing depth of 2-3 nm [19]. It should be noted that XPS profiles were calibrated to the adventitious C 1s peak position [20] and then normalized to their respective N 1s peak intensities.…”

Section: Device Characteristics and Discussionmentioning

confidence: 99%

Current Collapse Reduction in AlGaN/GaN HEMTs by High-Pressure Water Vapor Annealing

Asubar

Kobayashi

Yoshitsugu

et al. 2015

IEEE Trans. Electron Devices

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We have demonstrated for the first time a remarkable reduction of current collapse in AlGaN/GaN highelectron-mobility transistors (HEMTs) by high-pressure water vapor annealing (HPWVA). The device subjected to HPWVA exhibited considerably low dynamic ON-resistance (R ON ), suggesting highly improved performance of these devices. Analyses of the results on normalized dynamic R ON experiments have shown the elimination of deeper traps by HPWVA, leading to the substantially reduced current collapse. X-ray photoelectron spectroscopy (XPS) studies revealed a significant increase in the oxygen core-level O 1s peak. Moreover, angleresolved XPS suggested the formation of surface oxide layer. These results indicate that the effective reduction of current collapse in the HPWVA-processed samples is likely due to the incorporation of active oxygen species generated by the HPWV into the AlGaN surface. These oxygen atoms eventually fill up near-surface nitrogen vacancies and promote the formation of Ga 2 O 3 native oxide and possibly Ga 2 O suboxide, which is known to be an excellent III-V surface passivant. HPWVA is a relatively simple, low-damage, and low-temperature process, and hence, it is found to be a highly feasible and promising alternative for realizing AlGaN/GaN HEMTs with improved performance.Index Terms-AlGaN/GaN high-electron-mobility transistor (HEMT), current collapse, high-pressure water vapor annealing (HPWVA), normalized dynamic R ON (NDR), ON-resistance, X-ray photoelectron spectroscopy (XPS).

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Improvements of electronic and optical characteristics of n-GaN-based structures by photoelectrochemical oxidation in glycol solution

Cited by 14 publications

References 45 publications

Crystallization Effects of Nanocrystalline GaN Films on Field Emission

Crystallization Effects of Nanocrystalline GaN Films on Field Emission

Characterization of interface states in Al2O3/AlGaN/GaN structures for improved performance of high-electron-mobility transistors

Current Collapse Reduction in AlGaN/GaN HEMTs by High-Pressure Water Vapor Annealing

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