Optical Conductivity Studies in Heavily Boron-Doped Diamond

The optical transmittance and reflectance of heavily boron-doped (2 × 1020 cm—3 < [B] < 2 × 1021 cm—3) epitaxial diamond layers deposited by MPCVD were measured in the infrared range. While T-dependent measurements confirmed the metallic character of such films, the overall spectral features were well reproduced by introducing Drude components in the fitting expression for the optical conductivity. The associated microscopic transport parameters were quantitatively compared to those resulting from preliminary transport measurements performed on the same samples. We show that room-temperature FTIR reflectance measurements provide an easy contactless characterization of the transport properties of such p+ films, and we discuss what new information on carrier–phonon interaction as well as on the transport mechanism in the impurity band might be gained from temperature-dependent spectroscopic data.