Charge Trapping at Surface in GaN HEMTs

Hsiang Chen, Phillip Preecha, John Lai, Guann-Pyng Li
Dept. of Electrical Engineering, Univ. of California, Irvine, Irvine, CA 92697,
Phone: 1-949-824-2047 Fax:1-949-8242047 E-mail:
Keywords: GaN HEMT, electroluminescence, off-state breakdown, hole trapping, threshold voltage

Electron trapping after on-state stress and hole trapping after off-state breakdown stress has been observed by comparing the EL images and electrical characteristics in GaN HEMTs. Temperature measurement and 2D device simulation has been done to confirm the hole trapping phenomenon. With off-state breakdown stress, three devices all showed the same trend of electrical characteristics changes – a decrease of the threshold voltage and an increase of the gate leakage current. The changes of electrical characteristics were similar in different devices, but the changes in EL images varied. The technique promises a potential characterization tool for device and material screening.
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