A simple method for the creation of Ohmic contact to 2-D electron gas (2DEG) in AlGaN/GaN high electron-mobility transistors (HEMTs) using Cr/Graphene layer is demonstrated. A weak temperature dependence of this Ohmic contact observed in the range 77 to 300 K precludes thermionic emission or trap-assisted hopping as possible carrier-transport mechanisms. It is suggested that the Cr/Graphene combination acts akin to a doped n-type semiconductor in contact with AlGaN/GaN heterostructure, and promotes carrier transport along percolating Al-lean paths through the AlGaN layer. This new use of graphene offers a simple and reliable method for making Ohmic contacts to AlGaN/GaN heterostructures, circumventing complex additional processing steps involving high temperatures. These results could have important implications for the fabrication and manufacturing of AlGaN/GaN-based microelectronic and optoelectronic devices/sensors of the future.
@article{arxiv.1301.1952,
title = {Ohmic Contact Formation Between Metal and AlGaN/GaN Heterostructure via Graphene Insertion},
author = {Pil Sung Park and Kongara M. Reddy and Digbijoy N. Nath and Zhichao Yang and Nitin P. Padture and Siddharth Rajan},
journal= {arXiv preprint arXiv:1301.1952},
year = {2013}
}