Performance Comparison of Au-Based and Au-Free AlGaN/GaN HEMT on Silicon

Niranjan, S and Rao, A and Muralidharan, R and Sen, P and Nath, DN (2022) Performance Comparison of Au-Based and Au-Free AlGaN/GaN HEMT on Silicon. In: IEEE Transactions on Electron Devices, 69 (3). pp. 1014-1019.

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Abstract

We report on the electrical performance comparison of Au-based and Au-free AlGaN/GaN high electron mobility transistors (HEMTs) on silicon (Si). The chemical composition of both types of contacts, i.e., Ti/Al/Ti/W (Au-free) and Ti/Al/Ni/Au (Au-based) are studied using transmission electron microscope (TEM). For the former, the top W layer is found to be restricted in its interaction with the lower metal layers, leading to a continuous W cap at the contact surface which results in a 20× improvement in the surface roughness for the Au-free contacts. From transistor measurements, devices with Au-free contacts are found to exhibit +0.4 V shift in the threshold voltage and a 10× increase in the gate leakage which is attributed to the strain associated with the sputteredW-capping layer of the Ni/W gate-metal stack and plasma induced damage caused at the barrier surface due to high-power sputter deposition of gate contact. LowestRC value of 0.4 mm obtained for the Au-free Ohmic contacts is comparable to the RC value of 0.38 mm obtained for the Au-based Ohmic contacts used in this work.

Item Type:	Journal Article
Publication:	IEEE Transactions on Electron Devices
Publisher:	Institute of Electrical and Electronics Engineers Inc.
Additional Information:	The copyright for this article belongs to the Institute of Electrical and Electronics Engineers Inc.
Keywords:	Aluminum; Aluminum gallium nitride; CMOS integrated circuits; Deposition; Electric contactors; Electron mobility; Energy gap; Gallium nitride; High electron mobility transistors; III-V semiconductors; Surface roughness; Threshold voltage; Transmission electron microscopy; Wide band gap semiconductors, AlGaN/GaN high electron mobility transistor; AlGaN/GaN high electron mobility transistors; Au free; Au-free process; CMOS compatibility; High electron-mobility transistors; Performance comparison; Rough surfaces; Sputter deposition.; Wide-band-gap semiconductor, Ohmic contacts
Department/Centre:	Division of Interdisciplinary Sciences > Centre for Nano Science and Engineering
Date Deposited:	16 Jun 2022 11:41
Last Modified:	16 Jun 2022 11:41
URI:	https://eprints.iisc.ac.in/id/eprint/73802

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