Evolution of surface morphology and properties of diamond films by hydrogen plasma etching

Abstract The micron-scale diamond film was prepared using hydrogen and methane as the mixed gas supplies via self-developed 3 kW/2,450 MHz microwave plasma chemical vapor deposition (MPCVD) equipment. On this basis, the evolution of the surface morphology, hydrophobicity, and electrical properties of samples under different hydrogen plasma etching times was investigated. The results indicate that the crystal edge and the top of the diamond grain were preferentially etched when etching time is less than 30 min. The surface roughness reduced from 0.217 to 0.205 μm, and the resistance value decreases from 3.17 to 0.35 MΩ. However, as the etch time increases to 120 min, the etching depth increases, and the surface roughness was increased. Simultaneously, the contact angles increased from 62.8° to 95.9°, which indicates that the surface of the diamond films exhibits more pronounced hydrophobicity. The treatment time of hydrogen plasma has no significant effect on the resistance value in the range of 0.26–0.50 MΩ. The mechanism of surface etching by hydrogen plasma was also discussed.