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The electrical current through silver contacts evaporated onto n-type gallium arsenide as a function of surface treatment is reported. Contacts to untreated gallium arsenide exhibit the expected high resistance. Surface cleaning by argon ion bombardment reduces the resistance by three orders of magnitude. The electrical resistance beyond 850 eV increases rapidly with ion bombardment energy. The resistance minimum at 850 eV is explained semiquantitatively in terms of a balance between cleaning and surface damage. This type of contact is appropriate for addition to a finished material whose properties are to be investigated, but may not be adequately ohmic for use on production devices.