Pil Sung Park, Kongara M. Reddy, Digbijoy N. Nath, Nitin P. Padture, Siddharth Rajan
We report on the electrical properties of graphene/AlGaN/GaN heterostructures using lateral graphene field-effect-transistors (FETs) and vertical metal-graphene-AlGaN-GaN diodes. From a comparison with graphene FETs on SiO2, it is found that a significant carrier mobility degradation is caused at the graphene/AlGaN interface which we attribute to fixed charges which neutralize polarization sheet charges at the AlGaN surface. Unexpectedly, the insertion of graphene between a metal and AlGaN was found to enable ohmic contact between the metal and semiconductor. This effect could be used as a simple manufacturable way to obtain ohmic contacts for high-electron-mobility-transistors (HEMTs.)
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http://arxiv.org/abs/1301.1952
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