Nanocarbon ohmic electrodes fabricated by coaxial arc plasma deposition for phosphorus-doped diamond electronics application

Abstract

n-Type (phosphorus-doped) diamond is a promising material for diamond-based electronic devices. However, realizing good ohmic contacts for phosphorus-doped diamonds limits their applications. Thus, the search for non-conventional ohmic contacts has become a hot topic for many researchers. In this work, nanocarbon ohmic electrodes with enhanced carrier collection efficiency were deposited by coaxial arc plasma deposition. The fabricated nanocarbon ohmic electrodes were extensively examined in terms of specific contact resistance and corrosion resistance. The circular transmission line model theory was used to estimate the charge collection efficiency of the nanocarbon ohmic electrodes in terms of specific contact resistance at a specific voltage range (5-10 V); they exhibited a specific contact resistance of 1 × 10-3 ωcm2. The result revealed one order reduction in the specific contact resistance and, consequently, a potential drop at the diamond/electrode interface compared to the conventional Ti electrodes. Moreover, the fabricated nanocarbon electrodes exhibited high mechanical adhesion and chemical inertness over repeated acid treatments. In device applications, the nanocarbon electrodes were evaluated for Ni/n-type diamond Schottky diodes, and they exhibited nearly one order enhancement in the rectification ratio and a fast charge collection at lower biasing voltages.