In situ boron doping of chemical-vapor-deposited diamond films

A systematic investigation of the boron doping of microwave-plasma-deposited diamond films was performed. Doping with levels up to 550 ppm was carried out in situ on undoped diamond film substrates in a microwave-plasma-assisted chemical vapor deposition with liquid trimethyl-, triethyl-, and tripropylborate and gaseous trimethylborane as doping sources. The dependence of the boron incorporation probability on the doping sources and on the process parameters was studied with secondary ion mass spectrometry. The doping-induced variations of phase quality and morphologic characteristics of the boron-doped diamond layers were investigated by means of scanning electron microscopy and Ramon spectroscopy. The incorporation of other impurities (i.e., hydrogen, nitrogen, oxygen, and silicon) were also determined by secondary ion mass spectrometry. The relations of the concentration of these impurities to the boron incorporation were also studied.