CHARACTERIZATION OF UNDOPED AND DOPED HOMOEPITAXIAL DIAMOND LAYERS PRODUCED BY MICROWAVE PLASMA CVD

Undoped and doped homoepitaxial diamond films were grown selectively on synthetic diamond substrates by microwave plasma chemical vapor deposition. Doping was carried out using B2O3 powder. The films were characterized using a Talystep profilometer, reflection high energy electron diffraction, Nomarski microscopy and scanning laser microscopy. The electrical properties were specified by current-voltage and Hall effect measurements. The electric conductivity of the substrates and of the homoepitaxial layers was measured at temperatures up to 400-degrees-C. The morphology of the undoped films changes from scaly growth at low methane concentrations to layer growth at higher concentrations. The conductivity of the undoped films is lower than the conductivity of the substrate. The electric conductivity of boron-doped films shows an activation energy depending on boron concentration.