Investigation of ring structures for metal-semiconductor contact resistance determination

Abstract Solutions to voltage profiles obtained from radial current flow under metal ring structures on thin semiconductor layers are examined in the light of results obtained for flow under rectangular structures. By using series expansions it is shown that expressions obtained in the case of circular structures reduce to those of the rectangular case for values of ring radius r ≳ 30 L t , at all points on the ring, and where L t is the transfer length—a property of the materials concerned and the specific contact resistance. In addition, expressions are developed to cover the range of values 3 L t ≲ r ≲ 30 L t and r ≲ 3 L t . These are then used to obtain new expressions from which values of specific contact resistance and semicondutor sheet resistance (under contacts) can be found.