Phosphorus Doping Efficiency Considerations for Pulsed Deposition Techniques

Phosphorus doped, n‐type diamond is the enabling factor for bipolar diamond devices. Several decades of research have demonstrated the challenges to prepare material suitable for practical diamond devices. While various groups report phosphorus incorporation, incorporation efficiency is rarely the primary focus, and is typically derived from precursor‐flow instead of reactive species that actually govern incorporation at the growth surface. This research investigates the phosphorus incorporation efficiency based on diamond growth‐ and doping species, the CH 3 and PH radicals, and for a pulsed deposition technique. Here, the methane flow is periodically interrupted while maintaining other growth parameters constant, including the dopant flow. Residual gas analysis (RGA) is operated in a differentially pumped configuration to measure, in real time, growth and doping species concentrations. In conjunction with secondary ion mass spectroscopy (SIMS) the phosphorus incorporation is then related to the plasma chemistry. With the measured growth parameters and SIMS data, an overgrowth‐versus‐desorption kinetic model resolved by Burton–Cabrera–Frank (BCF) step‐flow theory is developed and fitted to the data. Good agreement between model and experiment emerges with a derived maximum incorporation efficiency η ind , referenced to the CH 3 and PH radicals, of about 27% for a maximum phosphorus incorporation of 7 × 10 19 cm −3 .