Investigation on Current Collapse of AlGaN/GaN HFET by Gate Bias Stress

Jin-Ping AO  Yuya YAMAOKA  Masaya OKADA  Cheng-Yu HU  Yasuo OHNO  

IEICE TRANSACTIONS on Electronics   Vol.E91-C   No.7   pp.1004-1008
Publication Date: 2008/07/01
Online ISSN: 1745-1353
DOI: 10.1093/ietele/e91-c.7.1004
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Section on Heterostructure Microelectronics with TWHM 2007)
Category: Nitride-based Devices
AlGaN/GaN,  heterojunction field-effect transistor,  current collapse,  gate bias stress,  

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The mechanism of current collapse of AlGaN/GaN heterojunction field-effect transistors (HFETs) was investigated by gate bias stress with and without illumination. It is clarified that there are two positions where negative charges accumulate, at the gate edge and in the bulk epi-layer. In the gate-edge mode, the charge comes either through the passivation film or the AlGaN layer, depending on the resistance of the films. Reduction of leakage current in the passivation film will be important to suppress the surface-related collapse.