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.

Overcoming the impact of post-annealing on uniformity of diamond (100) Schottky barrier diodes through corrosion-resistant nanocarbon ohmic contacts

“…This interfacial stability and mechanical adhesion in a highly corrosive medium are due to the partial sp 3 bonds at the diamond/nanocarbon interface which then becomes less susceptible to degradation. The complete removal of the nanocarbon ohmic contacts from the diamond surface has been observed after twelve acid treatment sessions similar to those observed for nanocarbon ohmic contacts for phosphorus-doped diamonds [26].…”

“…By skipping the post-annealing step, the uniformity of SBD parameters fabricated on wet chemically O-terminated diamond surfaces has been obviously improved with a very small standard deviation. The potential of nanocarbon ohmic electrodes over conventional Ti ohmic contacts has been proposed for both phosphorus-doped [26] and boron-doped diamonds. The proposed nanocarbon ohmic electrodes for semiconducting diamond-based electronic applications could enhance the degree of freedom of diamond lateral Schottky device fabrication.…”

“…The graphical representation of the CAPD apparatus is shown in figure 1. The detailed fabrication procedures can be found in our previous reports [26,27]. Concentric nanocarbon electrodes with different inter-electrode spacings (d) ranging from 4 μm to 16 μm were formed using the standard photolithography lift-off technique and subsequent oxygen plasma reactive ion etching.…”

“…In our recent report [26], we have proposed a low specific contact resistance and corrosion-resistant nanocarbon-based ohmic contact strategy for phosphorus-doped diamonds. The alternative nanocarbon ohmic contacts exhibited excellent contact behavior with low specific contact resistance than the conventional Ti-based ohmic contacts.…”

Corrosion‐Resistive and Low Specific Contact Resistance Ohmic Contacts to Semiconducting Diamonds Using Nanocarbon Electrodes

“…[ 12–14 ] In our most recent work, we demonstrated an efficient ohmic contact for phosphorus‐doped n‐type diamonds through nanocarbon electrodes fabricated by the coaxial arc plasma deposition (CAPD) method. [ 15 ] The nanocarbon electrodes exhibited enhanced charge collection efficiency over the conventional Ti‐based ohmic electrodes. The current supplementation through nanocarbon ohmic electrodes is correlated with the tightly bonded diamond/nanocarbon sp 2 carbon phases at the interface.…”