The effect of substrate temperature and growth rate on the doping efficiency of single crystal boron doped diamond

• Heavily boron-doped diamond samples were grown with substrate temperatures of 850°C - 1050°C.
• Samples grown at 950°C show fewer defects and higher doping efficiency than those grown at 850°C.
• Samples with higher growth rates show lower boron doping efficiency.
• A proposed carbon flux ratio is more predictive of boron content than the gas phase [B]/[C] ratio.

The substrate growth temperature dependence of the plasma gas-phase to solid-phase doping efficiency in single crystal, boron doped diamond (BDD) deposition is investigated. Single crystal diamond (SCD) is grown by microwave plasma assisted chemical vapor deposition (MPACVD) on high pressure, high temperature (HPHT) type Ib substrates. Samples are grown at substrate temperatures of 850–950 °C for each of five doping concentration levels, to determine the effect of the growth temperature on the doping efficiency and defect morphology. The substrate temperature during growth is shown to have a significant effect on the grown sample defect morphology, and a temperature dependence of the doping efficiency is also shown. The effect of the growth rate on the doping efficiency is discussed, and the ratio of the boron concentration in the gas phase to the flux of carbon incorporated into the solid diamond phase is shown to be a more predictive measure of the resulting boron concentration than the gas phase boron to carbon ratio that is more commonly reported.

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