Synthesis and Electrical Properties of Phosphorus-Doped Homoepitaxial Diamond (111) by Microwave Plasma-Assisted Chemical Vapor Deposition Using Triethylphosphine as a Dopant Source

A phosphorus-doped (111) diamond film was formed homoepitaxially on a nondoped diamond film, which was also formed homoepitaxially on a type Ib (111) diamond substrate, by microwave plasma-assisted chemical vapor deposition using CH₄ as the carbon source and triethylphosphine (TEP, P(C₂H₅)₃) as the dopant source. The P-doped film, which was approximately 800 nm in thickness, exhibited an n-type conduction in the temperature range of 100–500 K. This represents the first such observation, for a film prepared using TEP as the dopant. The activation energy for carrier concentration was 0.09 eV in the range of 145–500 K. The Hall mobility reached a maximum of approximately 3.5 cm²/(V·s) at 145 K and decreased to 0.15 cm²/(V·s) at 500 K. Phosphorus was uniformly incorporated into the diamond film, as evidenced by secondary ion mass spectrometry.