Low-temperature spectroscopic study of n-type diamond

A spectroscopic study of epitaxial phosphorus-doped n-type diamond films, p repared by the chemical vapor deposition (CVD) technique, was carried out u sing the constant photocurrent method (CPM). Liquid nitrogen temperature CP M 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 yield s 0.56 eV optical excitation energy for the first level (denoted as X-P1) a nd 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 s amples. The X-P2-defect level remains unidentified. Liquid helium temperatu re measurements for a high-electrical mobility n-type diamond sample show P -related oscillatory photoconductivity.