Synthesis of phosphorus-doped homoepitaxial diamond by microwave plasma-assisted chemical vapor deposition using triethylphosphine as the dopant

Triethylphosphine [TEP, P(C₂H₅)3] was used as a dopant for homoepitaxial (100) and (111) phosphorus-doped diamond films, which were formed by microwave plasma-assisted chemical vapor deposition using CH₄ as the carbon source. The growth rate of TEP-doped (100) diamond increased with increasing atomic ratio of phosphorus to carbon in the gas phase, from 300 nm h^-1 at 0 ppm to 800 nm h^-1 at 10 000 ppm at 850 °C. TEP-doped (100) diamond films deposited at temperatures below 850 °C were smooth and homoepitaxial, whereas those deposited above 950 °C as well as the TEP-doped (111) films formed at 750-1050 °C were polycrystalline. Phosphorus was found to be uniformly incorporated into the diamond film, as evidenced by secondary ion mass spectrometry. The Hall conductivity of the TEP-doped films remained low.