TITLE

Evolution of structural defects associated with electrical degradation in AlGaN/GaN high electron mobility transistors

AUTHOR(S)
Makaram, Prashanth; Joh, Jungwoo; del Alamo, Jesús A.; Palacios, Tomás; Thompson, Carl V.
PUB. DATE
June 2010
SOURCE
Applied Physics Letters;6/7/2010, Vol. 96 Issue 23, p233509
SOURCE TYPE
Academic Journal
DOC. TYPE
Article
ABSTRACT
We have investigated the surface morphology of electrically stressed AlGaN/GaN high electron mobility transistors using atomic force microscopy and scanning electron microscopy after removing the gate metallization by chemical etching. Changes in surface morphology were correlated with degradation in electrical characteristics. Linear grooves formed along the gate edges in the GaN cap layer for all electrically stressed devices. Beyond a critical voltage that corresponds to a sharp increase in the gate leakage current, pits formed on the surface at the gate edges. The density and size of the pits increase with stress voltage and time and correlate with degradation in the drain current and current collapse. We believe that high mechanical stress in the AlGaN layer due to high-voltage stressing is relieved by the formation of these defects which act as paths for gate leakage current and result in electron trapping and degradation in the transport properties of the channel underneath.
ACCESSION #
51378938

 

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