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Open AccessArticle

Electrical and Structural Properties of All-Sputtered Al/SiO2/p-GaN MOS Schottky Diode

1
School of Basic Sciences, Tra Vinh University, Tra Vinh 87000, Vietnam
2
Department of Materials Science and Engineering, National Taiwan University of Science and Technology, Taipei 10607, Taiwan
3
School of Engineering and Technology, Tra Vinh University, Tra Vinh 87000, Vietnam
4
School of Engineering and Technology, Can Tho University, Can Tho 94000, Vietnam
*
Authors to whom correspondence should be addressed.
Coatings 2019, 9(10), 685; https://doi.org/10.3390/coatings9100685
Received: 22 September 2019 / Revised: 10 October 2019 / Accepted: 14 October 2019 / Published: 21 October 2019
(This article belongs to the Special Issue Advanced Strategies in Thin Film Engineering by Magnetron Sputtering)
The all-sputtered Al/SiO2/p-GaN metal-oxide-semiconductor (MOS) Schottky diode was fabricated by the cost-effective radio-frequency sputtering technique with a cermet target at 400 °C. Using scanning electron microscope (SEM), the thicknesses of the electrodes, insulator SiO2 layer, and p-GaN were found to be ~250 nm, 70 nm, and 1 µm, respectively. By Hall measurement of a p-Mg-GaN film on an SiO2/Si (100) substrate at room temperature, the hole’s concentration (Np) and carrier mobility (μ) were found to be Np = 4.32 × 1016 cm−3 and μ = 7.52 cm2·V−1·s−1, respectively. The atomic force microscope (AFM) results showed that the surface topography of the p-GaN film had smoother, smaller grains with a root-mean-square (rms) roughness of 3.27 nm. By I–V measurements at room temperature (RT), the electrical properties of the diode had a leakage current of ~4.49 × 10−8 A at −1 V, a breakdown voltage of −6 V, a turn-on voltage of ~2.1 V, and a Schottky barrier height (SBH) of 0.67 eV. By C–V measurement at RT, with a frequency range of 100–1000 KHz, the concentration of the diode’s hole increased from 3.92 × 1016 cm−3 at 100 kHz to 5.36 × 1016 cm−3 at 1 MHz, while the Fermi level decreased slightly from 0.109 to 0.099 eV. The SBH of the diode at RT in the C–V test was higher than in the I–V test because of the induced charges by dielectric layer. In addition, the ideality factor (n) and series resistance (Rs) determined by Cheung’s and Norde’s methods, other parameters for MOS diodes were also calculated by C–V measurement at different frequencies. View Full-Text
Keywords: MOS Schottky diode; SBH; IV measurement; CV measurement; Cheung’s and Norde’s methods MOS Schottky diode; SBH; IV measurement; CV measurement; Cheung’s and Norde’s methods
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MDPI and ACS Style

Thi, T.A.T.; Kuo, D.-H.; Cao, P.T.; Quoc-Phong, P.; Nghi, V.K.; Tran, N.P.L. Electrical and Structural Properties of All-Sputtered Al/SiO2/p-GaN MOS Schottky Diode. Coatings 2019, 9, 685.

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