Optical properties of boron-doped diamond

TL;DR

This study investigates how boron doping affects the optical and electronic properties of diamond films, revealing impurity band formation, lattice distortion, and strong electron-phonon coupling.

Contribution

It provides new insights into the electronic structure evolution and phonon interactions in boron-doped diamond using optical reflectivity measurements.

Findings

Impurity band forms near the valence band top with boron doping

Boron induces local lattice distortion activating infrared phonon modes

Strong electron-phonon coupling evidenced by antiresonance in conductivity spectrum

Abstract

We report optical reflectivity study on pure and boron-doped diamond films grown by a hot-filament chemical vapor deposition method. The study reveals the formation of an impurity band close to the top of the valence band upon boron-doping. A schematic picture for the evolution of the electronic structure with boron doping was drawn based on the experimental observation. The study also reveals that the boron doping induces local lattice distortion, which brings an infrared-forbidden phonon mode at 1330 cm$^{-1}$ activated in doped sample. The antiresonance characteristic of the mode in conductivity spectrum evidences the very strong coupling between electrons and this phonon mode.