Specific Contact Resistance Measurements of Ohmic Contacts to SemiconductingDiamond

摘要

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 10 to the 19th power acceptors/cu cm on <100> and <110> type IIa substrates; type IIb diamonds 0.25 mm thick, and type IIb diamonds thinned to 0.035-O.05 nm 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 x 10 to the -2 power ohms sq cm for heavily doped films to 1 x 10 to the -2 power ohms for lightly doped bulk samples. A simple analysis shows that the contacts to highly doped layers are suitable for device applications. jg.