Benbakhti, B, Duffy, SJ, Mattalah, M, Zhang, WD, Bouchilaoun, M, Boucherta, M, Kalna, K, Bourzgui, N, Maher, H and Soltani, A (2017) Low Source/Drain Contact Resistance for AlGaN/GaN HEMTs with High Al Concentration and Si-HP [111] Substrate. ECS Journal of Solid State Science and Technology, 6 (11). ISSN 2162-8769

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Abstract

An optimized fabrication process of ohmic contacts is proposed to reduce the source/drain access resistance (RC) and enhance DC/RF performance of AlGaN/GaN HEMTs with a high Al concentration. We show that source/drain RC can be considerably lowered by (i) optimally etching into the barrier layer using Ar+ ion beam, and by (ii) forming recessed contact metallization using an optimized Ti/Al/Ni/Au (12 nm/200 nm/40 nm/100 nm) multilayers. We found that a low RC of ∼0.3 Ω.mm can be achieved by etching closer to the 2-Dimensional Electron Gas (2DEG) at an optimum etching depth, 75% of the barrier thickness, followed by a rapid thermal annealing at 850°C. This is due to the very small distance between the alloy and the 2DEG (higher electric field) as shown by 2D drift-diffusion simulations combined with Transmission Line Model (TLM) extractions.

Item Type:	Article
Subjects:	T Technology > TK Electrical engineering. Electronics. Nuclear engineering
Divisions:	Electronics & Electrical Engineering (merged with Engineering 10 Aug 20)
Publisher:	Electrochemical Society
Date Deposited:	28 Sep 2017 10:15
Last Modified:	04 Sep 2021 11:10
DOI or ID number:	10.1149/2.0111711jss
URI:	https://researchonline.ljmu.ac.uk/id/eprint/7228

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