A Mechanism of Enhancement-Mode Operation of AlGaN/GaN MIS-HFET

Daigo KIKUTA  Jin-Ping AO  Junya MATSUDA  Yasuo OHNO  

Publication
IEICE TRANSACTIONS on Electronics   Vol.E89-C   No.7   pp.1031-1036
Publication Date: 2006/07/01
Online ISSN: 1745-1353
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Section on Heterostructure Microelectronics with TWHM2005)
Category: GaN-Based Devices
Keyword: 
HFET,  GaN,  AlGaN,  MIS,  insulator,  enhancement,  

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Summary: 
A model for the enhancement-mode operation of an AlGaN/GaN metal-insulator-semiconductor heterostructure field-effect transistor (MIS-HFET) under DC and AC conditions is proposed. In DC operation at positive gate voltages, the MIS-HFET can be divided into a transistor area and a resistor area due to the diode nature of the insulator/AlGaN interface. The transistor area shrinks with the increases in gate voltage. The intrinsic-transistor gate-length reduction causes a drain current increase. The I-V characteristics based on the gradual channel approximation are derived. The ID hysteresis of the MIS-HFET is investigated by a circuit simulation using SPICE. We have confirmed that the hysteresis was caused by the phase difference between the potential variation of the gate insulator/AlGaN interface and that of the gate electrode due to CR components in the gate structure.