AVS 52nd International Symposium
    Electronic Materials and Processing Wednesday Sessions
       Session EM-WeA

Paper EM-WeA4
Indium-based Ohmic Contacts to n-GaSb and the Influence of Surface Passivation

Wednesday, November 2, 2005, 3:00 pm, Room 309

Session: Contacts to Semiconductors
Presenter: J.A. Robinson, The Pennsylvania State University
Authors: J.A. Robinson, The Pennsylvania State University
S.E. Mohney, The Pennsylvania State University
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Gallium antimonide and related ternary and quaternary semiconductors have shown great potential for electronic devices as well as optoelectronic devices in the 0.3 - 8 µm wavelength range. High quality ohmic contacts help ensure device reliability and improve performance by providing a low resistance, a uniform interface morphology, and minimal semiconductor consumption. Pd-based contacts to n-GaSb that do not include In provide specific contact resistance values as low as 5 x 10@super -6@ @Omega@-cm@super 2@. However, by adding In, the specific contact resistance is reduced by 80%. We present two high quality In-based contacts that include Pd. Initial experiments included a Pd/In/Pd/Pt/Au contact that provides a specific contact resistance of 1.8 x 10@super -6@ @Omega@-cm@super 2@ using a modified pre-metallization surface treatment that involves 2.1% (NH@sub 4@)@sub 2@S. However, the surface and interfacial reaction morphology of the Pd/In/Pd/Pt/Au contact was less than optimal. As a result, sputtered Pd@sub 3@In@sub 7@/X/Au (X = Pt,W,WSi@sub 2@, or WSiN) contacts were explored as a means to improve reaction morphology and thermal stability. Contacts utilizing WSiN provide a specific contact resistance of approximately 3 x 10@super -6@ @Omega@-cm@super 2@ using a conventional surface treatment, and 1.8 x 10@super -6@ @Omega@-cm@super 2@ when the modified surface treatment is used. While the Pd@sub 3@In@sub 7@/WSiN/Au contact provides specific contact resistance values comparable to the best reported In-based contacts, this contact exhibits an improved reaction morphology and better thermal stability compared to other contacts.