Optical spectroscopic study of n-type diamond

Abstract

Preparation of n-type diamond has been one of the challenges in the diamond field, not successful in the past. Recently the group at NIRIM has succeeded in deposition of thin n-type P-doped CVD diamond films. Hall effect measurements confirmed n-type conductivity with the activation energy of the carrier concentration of 0.40-0.60 eV. Here, we present the first spectroscopic study of the phosphorus optical activity in diamond, using the constant photocurrent method [3] (CPM) and an optical absorption technique - photothermal deflection spectroscopy (PDS) [4]. Two new optically active defects are detected in the gap of P-doped CVD diamond: the first at about 0.56 eV (denoted as XP1) and the second one at about 0.81 eV (denoted as XP2) of the optical excitation energy. Additionally, at liquid-He temperature, a phonon-induced oscillatory photoconductivity is observed, allowing to estimate the position of P-excited states.