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Low Source/Drain Contact Resistance for AlGaN/GaN HEMTs with High Al Concentration and Si-HP [111] Substrate

S. J. Duffy, B. Benbakhti, M. Mattalah, W. Zhang, M. Bouchilaoun, M. Boucherta, K. Kalna, N. Bourzgui, H. Maher, A. Soltani, Karol Kalna Orcid Logo

ECS Journal of Solid State Science and Technology, Volume: 6, Issue: 11, Pages: S3040 - S3043

Swansea University Author: Karol Kalna Orcid Logo

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DOI (Published version): 10.1149/2.0111711jss

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 usi...

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Published in: ECS Journal of Solid State Science and Technology
ISSN: 2162-8769 2162-8777
Published: 2017
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URI: https://cronfa.swan.ac.uk/Record/cronfa35704
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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.
Keywords: AlGaN/GaN HEMTs, Ohmic Contact, TLM Model
College: College of Engineering
Issue: 11
Start Page: S3040
End Page: S3043