Low-temperature spectroscopic study of n-type diamond

Abstract

A spectroscopic study of epitaxial phosphorus-doped n-type diamond films, prepared by the chemical vapor deposition (CVD) technique, was carried out using the constant photocurrent method (CPM). Liquid nitrogen temperature CPM data show two new optically active defects in the gap of the P-doped CVD diamond film. A theoretical fitting of the optical cross-section data yields 0.56 eV optical excitation energy for the first level (denoted as X-P1) and 0.81 eV for the second level (denoted as X-P2) The X-P1 optical data are in good agreement with Hall measurements, showing about the same value for the (thermal) activation energy of the carrier concentration for P-doped samples. The X-P2-defect level remains unidentified. Liquid helium temperature measurements for a high-electrical mobility n-type diamond sample show P-related oscillatory photoconductivity.