Hydrogen induced vibrational and electronic transitions in chemical vapor deposited diamond, identified by isotopic substitution

Abstract

Homoepitaxial diamond films grown by chemical vapor deposition from ¹²C and ¹³C containing gases have been studied by Fourier transform infrared spectroscopy. A sharp absorption band observed at 3123 cm⁻¹ is attributed to a CH vibrational absorption. It resembles the previously observed 3107 cm⁻¹ absorption band in natural diamond. Isotopic replacement of carbon, hydrogen, and nitrogen by ¹³C, ²H, and ¹⁵N reveals, that a CH center without nitrogen participation is responsible for this new absorption. Furthermore, new hydrogen related electronic transitions have been observed around 7300 cm⁻¹. These lines shift to higher energies in ¹³C crystals, in accordance with the increase of the electronic band gap.