CONDUCTION MECHANISMS IN W AND WSIX OHMIC CONTACTS TO INGAN AND INN

The temperature dependence of the specific contact resistance of Wand WSi0.44 contacts On n(+) In0.65Ga0.35N and InN was measured in the ran ge -50-125 degrees C. The results were compared to theoretical values for different conduction mechanisms, to further elucidate the conducti on mechanism in these contact structures. The data indicates the condu ction mechanism is field emission for these contact schemes for all bu t as-deposited metal to InN where thermionic emission appears to be th e dominant mechanism. The contacts were found to produce low specific resistance ohmic contacts to InGaN at room temperature, rho(c) similar to 10(-7) Omega . cm(2) for W and rho(c) of 4 x 10(-7) Omega . cm(2) for WSix. InN metallized with W produced ohmic contacts with rho(c) si milar to 10(-7) Omega . cm(2) and rho(c) similar to 10(-6) Omega . cm( 2) for WSix at room temperature. (C) 1997 Elsevier Science Ltd.