Effects of argon presputtering on the formation of aluminum contacts on polycrystalline diamond

Abstract

The results of in vacuo x‐ray photoelectron spectroscopy and Auger electron spectroscopy of Al‐diamond interfaces for Al overlayer thicknesses up to 10 Å are presented. Postdeposition annealing effects up to 430 °C are also discussed. Ex situ current‐voltage (I‐V) measurements were also made on thick (∼1500 Å) Al contacts on diamonds. The as‐grown diamond surface, on which Al was a rectifying contact, did not chemically interact with Al, even after annealing. An Ar⁺‐sputtered diamond surface, on the other hand, did react with Al to form Al—C bonds upon annealing at temperatures as low as 430 °C. Al on the sputtered surface resulted in an ohmic contact. The distortion of the diamond network and formation of vacancies and unsatisfied bonds via Ar⁺ sputtering of the diamond surface change the I‐V characteristics of the Al contact and also facilitate the solid state interdiffusion of Al and C as well as interface reactions at elevated temperatures.