Specific contact resistance measurements of ohmic contacts to semiconducting diamond

A simplified version of the specific contact resistance measurement scheme of G. K. Reeves [Solid State Electronics 23, 487 (1980)] has been developed. Its applicability to semiconducting diamond is demonstrated using four sample types: epitaxial films doped to mid 1019 acceptors/cm3 on 〈100〉 and 〈110〉 type IIa substrates; type IIb diamonds 0.25 mm thick, and type IIb diamonds thinned to 0.035–0.05 mm thick. The ohmic contacts were based on a solid‐state annealing process using carbide forming metals. The measured specific contact resistance depends mainly on the doping level in the diamond. Measured values ranged from 8×10−6 Ω cm2 for heavily doped films to 1×10−2 Ω cm2 for lightly doped bulk samples. A simple analysis shows that the contacts to highly doped layers are suitable for device applications.