Improved recess-ohmics in AlGaN/GaN high-electron-mobility transistors with AlN spacer layer on silicon substrate

Authors

  • Subramaniam Arulkumaran,

    Corresponding author
    1. MMIC Design Center, Temasek Laboratories@NTU, Nanyang Technological University, 50 Nanyang Drive, Research Techno Plaza, 637553 Republic of Singapore
    2. School of EEE, Division of Microelectronics, Nanyang Technological University, 639798 Republic of Singapore
    • Phone: +65-6790-5906, Fax: +65-6790-0215
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  • Ng Geok Ing,

    1. MMIC Design Center, Temasek Laboratories@NTU, Nanyang Technological University, 50 Nanyang Drive, Research Techno Plaza, 637553 Republic of Singapore
    2. School of EEE, Division of Microelectronics, Nanyang Technological University, 639798 Republic of Singapore
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  • Vicknesh Sahmuganathan,

    1. MMIC Design Center, Temasek Laboratories@NTU, Nanyang Technological University, 50 Nanyang Drive, Research Techno Plaza, 637553 Republic of Singapore
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  • Liu Zhihong,

    1. MMIC Design Center, Temasek Laboratories@NTU, Nanyang Technological University, 50 Nanyang Drive, Research Techno Plaza, 637553 Republic of Singapore
    2. School of EEE, Division of Microelectronics, Nanyang Technological University, 639798 Republic of Singapore
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  • Bryan Maung

    1. MMIC Design Center, Temasek Laboratories@NTU, Nanyang Technological University, 50 Nanyang Drive, Research Techno Plaza, 637553 Republic of Singapore
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Abstract

A systematic investigation of recess-ohmic contact by inductively coupled plasma etching using four layers Ti/Al/Ni/Au metal on un-doped AlGaN/GaN HEMT structure with a thin AlN spacer layer grown on silicon substrate were performed. Although the insertion of the thin AlN spacer layer effectively increases the two-dimensional electron gas concentration and electron mobility due to the enhanced 2DEG confinement, it causes much difficulty in forming ohmic contacts. This problem has been resolved by recess-ohmic approach prior to ohmic metalization. Improved HEMT characteristics were demonstrated by this technique. About 17.5% of increase in IDmax and 12.5% of increase in gmmax were observed by recess ohmics. This improved device performance is due to the reduction of Rc, Rd and Rs values by recess-ohmics. From this investigation, we found that recess-ohmics are essential to achieve high performance device characteristics in un-doped AlGaN/GaN HEMTs with AlN spacer layer grown on Si substrate (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

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