Self-aligned Recessed Ohmic Contacts for GaN-based High Electron Mobility Transistors

Al-Khalidi, A. , Macfarlane, D. and Wasige, E. (2012) Self-aligned Recessed Ohmic Contacts for GaN-based High Electron Mobility Transistors. UK Nitride Consortium 2012, Sheffield, UK, 4-5 Jul 2012.

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Abstract

This paper will describe the performance of recessed Ohmic contacts of Gallium Nitride (GaN) based high electron mobility transistors (HEMTs). Well optimized conventional (metal stack deposited on cap or barrier layer) fabrication processes for AlGaN/GaN and AlN/GaN devices achieve contact resistance values in the range of 0.3 Ωmm and 0.5 Ωmm (otherwise ~1Ωmm typically), respectively. Contact resistances under 0.1 Ωmm are required for the performance of these devices to be competitive. Low ohmic contact resistance can be achieved by recessing the ohmic contacts all the way through to the 2-DEG channel forming a side contact of the deposited metal with the 2-DEG channel which is believed to be a more efficient carrier transport mechanism rather than tunneling through the barrier. We will present results in which the conventional Ti/Al/Ni/Au metal stack is deposited on the surface, half way and all the way through to the 2-DEG channel of GaN-based HEMT material. The contact resistances are extracted from the characterisation of circular TLM test structures.

Item Type:Conference or Workshop Item
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Wasige, Professor Edward and Al-Khalidi, Dr Abdullah
Authors: Al-Khalidi, A., Macfarlane, D., and Wasige, E.
Subjects:T Technology > TK Electrical engineering. Electronics Nuclear engineering
College/School:College of Science and Engineering > School of Engineering > Electronics and Nanoscale Engineering

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