1. Monolithically Integrated Enhancement/Depletion-Mode A1GaN/GaN HEMT Inverters and Ring Oscillators Using CF4 Plasma Treatment.
- Author
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Yong Cai, Zhiqun Cheng, Wilson Chak Wah Tang, Kei May Lau, and Chen, Kevin J.
- Subjects
MODULATION-doped field-effect transistors ,GALLIUM nitride ,FIELD-effect transistors ,ELECTRIC inverters ,RAPID thermal processing ,ELECTRONIC circuits - Abstract
Fabrication and characterization of AlGaN/GaN HEMT inverters and ring oscillators utilizing integrated enhancement/depletion-mode (E/D-mode) AlGaN/GaN HEMTs are presented. The core technique is a CF4 plasma treatment that can effectively convert a D-mode AlGaN/GaN heterostructure to an E-mode heterostructure. A significant advantage of the plasma-treated E-mode HEMTs is that the gate current is reduced in both reverse- and forward-bias regions due to the effectively enhanced barrier height induced by the negatively charged fluorine ions in the AlGaN barrier. As a result, the input voltage swing is expanded by about 1 V for the E-mode HEMT, enabling convenient input/output logic level matching for multistage logic circuits such as ring oscillators. The fabricated 17-stage direct-coupled field-effect transistor logic ring oscillator using the 1-μm-gate technology can operate properly at a larger supply voltage of 3.5 V, and a minimum propagation delay of 130 ps/stage is achieved. [ABSTRACT FROM AUTHOR]
- Published
- 2006
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