Structural and Electronic Properties of Metals (Ti, Zr, Hf, Mo, and Al) Terminated Diamond (100) Surfaces

Diamond is an ultrawide bandgap semiconductor with outstanding properties such as thermal resistance capabilities and its electronic properties. Many literatures had described these characteristics of diamond (100), and through combining with metals, this diamond-metal materials possess low contact resistivity which allow easy electron flows between the surface but still be able to keep many diamond’s properties. However, the morphology purely between diamond and metals which significantly determine the property of the material has not yet been solved. This work will focus on exploring the intricacies of metal-diamond (100) contact, specifically at the interface layers and how it affects the Schottky Barrier Height of the system as it is a key component in creating a low contact resistance device. We will use GPAW for Density Functional Theory (DFT) calculations, using metals, Aluminum(Al), Molybdenum(Mo), Hafnium(Hf), Titanium(Ti), Zirconium(Zr), onto the diamond(100) surface. The partial density of states (PDOS) for each case was be analyzed for their corresponding electronic properties. Our results showed that the SBH of metals varied based on the number of metal atoms deposited onto the diamond (100) surface, with Ti reaching the highest SBH ranging from 0.52 eV to 2.23 eV and Al has the lowest SBH ranging from 0.08 eV to 1.09 eV. Further investigations show that at interface layer, metal-induced gap states (MIGS) played a significant role in altering the electronic properties of diamond such that the metal’s work function is not the sole determination for SBH as the Schottky Mott rule suggests. A model will be proposed such that through surface engineering, SBH or MIGS can be lower to lower resistivity in diamond-based electronic devices.