Refractory W Ohmic Contacts to H-Terminated Diamond

A major challenge facing diamond electronics is creating reliable and stable ohmic contacts to a hydrogen-terminated diamond (D:H) conducting surface. In this work, we explore a novel contact-first approach for creating refractory, scalable, and self-aligned ohmic contacts to D:H. Our contacts are based on W sputtered on O-terminated diamond followed by surface hydrogenation. We show that the H-plasma treatment provides a suitable thermal step to create the ohmic contact that relies on the formation of WC at the diamond surface. This thermal step also causes an order of magnitude increase in the W sheet resistance though the metallization that remains mechanically stable. The best contact resistance obtained in this work is 2.6 Omega-mm. We further demonstrate that the electrical contact takes place exclusively at the edge of the metal.