Atomically flat high-purity (100) diamond surfaces: Conductivity of hydrogen terminated diamond

Abstract

As an ideal candidate material for semiconductor devices, diamond exhibits remarkable potential in high-frequency and high-power applications due to its unique electrical properties. However, surface and bulk defects significantly impede its semiconductor performance due to the surface roughness scattering and impurity ionization scattering. In this work, based on the high-purity diamond materials with impurity levels below 5 ppb, atomic-level surface planarization of (100) single-crystal diamond (SCD) was achieved using a combination of mechanical polishing and chemical mechanical polishing (CMP) techniques. The effects of the surface roughness on the surface conductivity of hydrogen-terminated diamond were systematically evaluated. The results demonstrate that subsurface damage on the CMP diamond surface is removed through oxidation, reducing the surface roughness to Ra = 0.0973 nm over a 5 × 5 μm² area. Following hydrogenation treatment, the surface sheet resistance of hydrogen-terminated diamond with atomic-level flatness was significantly reduced to 1.03 kΩ/□, accompanied by a carrier mobility of 237 cm²/Vs. These findings confirm that CMP polishing significantly enhances the conductivity of hydrogen-terminated diamond. This work provides theoretical insights and technical guidance for the fabrication of high-performance diamond-based semiconductor devices.