The effect of nitrogen addition during high-rate homoepitaxial growth of diamond by microwave plasma CVD

The effect of nitrogen addition on growth rate, morphology and crystallinity during high-rate microwave plasma chemical vapor deposition (MPCVD) of diamond was investigated. Epitaxial diamond was grown on type Ib diamond (100) substrates using a 5-kW, 2.45-GHz microwave plasma CVD system with nitrogen addition in the methane and hydrogen source gases. In order to obtain high growth rates, we designed the substrate holders to generate high-density plasma. The growth rates ranged from 30 to 120 μm/h. The nitrogen addition enhanced the growth rate by a factor of 2 and was beneficial to create a macroscopic smooth (100) face avoiding the growth of hillocks. However, the (100) surfaces looked microscopically rough by bunched steps as the effect of nitrogen addition. The macroscopic smoothing during the growth enabled the long-term stable deposition required to obtain large crystals. The deposited diamond was characterized by optical microscope, Raman spectroscopy, cathodoluminescence spectroscopy and X-ray diffraction.