Influence of Large-Aspect-Ratio Surface Roughness on Electrical Characteristics of AlGaN/AlN/GaN HFETs
Journal article, 2012

The effect of large-aspect-ratio surface roughness of AlGaN/GaN wafers is investigated. The roughness has a surface morphology consisting of hexagonal peaks with maximum peak-to-valley height of more than 100 nm and lateral peak-to-peak distance between 25 and 100 mu m. Two epitaxial wafers grown at the same time on SiC substrates having different surface orientation and with a resulting difference in AlGaN surface roughness are investigated. Almost no difference is seen in the electrical characteristics of the materials, and the electrical uniformity of the rough material is comparable to that of the smoother material. The reliability of heterostructure field-effect transistors from both materials have been tested by stressing devices for up to 100 h without any significant degradation. No critical effect, from the surface roughness, on device fabrication is experienced, with the exception that the roughness will directly interfere with step-height measurements.


surface orientation (SO)


surface roughness





Martin Fagerlind

Chalmers, Microtechnology and Nanoscience (MC2), Microwave Electronics

I. Booker

Linköping University

P. Bergman

Linköping University

E. Janzen

Linköping University

Herbert Zirath

Chalmers, Microtechnology and Nanoscience (MC2), Microwave Electronics

Niklas Rorsman

Chalmers, Microtechnology and Nanoscience (MC2), Microwave Electronics

IEEE Transactions on Device and Materials Reliability

1530-4388 (ISSN)

Vol. 12 3 538-546

Subject Categories

Physical Sciences



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