Investigations of TiO2–AlGaN/GaN/Si-Passivated HFETs and MOS-HFETs Using Ultrasonic Spray Pyrolysis Deposition
| Autor: | Wen-Ching Sun, Sung-Yen Wei, Ching-Sung Lee, Wei-Chou Hsu, Bo-Yi Chou, Han-Yin Liu, Sheng-Min Yu, Chang-Luen Wu, Cheng-Long Yang |
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| Rok vydání: | 2015 |
| Předmět: | |
| Zdroj: | IEEE Transactions on Electron Devices. 62:1460-1466 |
| ISSN: | 1557-9646 0018-9383 |
| Popis: | Comparative studies for TiO2-passivated Al0.25Ga0.75N/GaN heterostructure FETs (HFETs) and TiO2-dielectric MOS-HFETs using nonvacuum ultrasonic spray pyrolysis deposition technique are made. Optimum device performances are obtained by tuning the layer thickness of TiO2 to 20 nm. High relative permittivity ( $k$ ) of 53.6 and thin effective oxide thickness of 1.45 nm are also obtained. Pulse-IV, Hooge coefficient ( $\alpha _{H}$ ), Transmission Electron Microscopy, and atomic force microscope have been performed to characterize the interface, atomic composition, and surface flatness of the TiO2 oxide. Superior improvements for the present TiO2-dielectric MOS-HFET/TiO2-passivated HFETs are obtained, including 47.6%/23.8% in two-terminal gate–drain breakdown voltage (BV $_{\rm GD})$ , 111%/22.2% in two-terminal gate-drain turn-ON voltage ( $V_{\mathrm{{\scriptscriptstyle ON}}})$ , 47.9%/39.4% in ON-state breakdown (BV $_{\rm DS})$ , 12.2%/10.2% in drain–source current density ( $I_{\rm DS})$ at $V_{\rm GS} = 0$ V ( $I_{\rm DSS0})$ , 27.2%/11.7% in maximum $I_{\rm DS}$ ( $I_{\rm DS, max})$ , 3/1-order enhancement in on/off current ratio ( $I_{\mathrm{{\scriptscriptstyle ON}}} / I_{\mathrm{{\scriptscriptstyle OFF}}})$ , 58.8%/17.6% in gate-voltage swing linearity, 25.1%/13.2% in unity-gain cutoff frequency ( $f_{T})$ , 40.6%/24.7% in maximum oscillation frequency ( $f_{\max })$ , and 33.8%/15.6% in power-added efficiency with respect to a Schottky-gated HFET fabricated on the identical epitaxial structure. The present MOS-HFET has also shown stable electrical performances when the ambient temperature is varied from 300 to 450 K. |
| Databáze: | OpenAIRE |
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