Photocurrent and optical absorption spectroscopic study of n-type phosphorus-doped CVD diamond

Abstract

A low-temperature spectroscopic study of epitaxial phosphorus-doped n-type CVD diamond films deposited on a type-Ia diamond crystal, was been carried out using the constant photocurrent method (CPM). Two new defect levels in the gap of CVD diamond were detected. A numerical fitting of the optical cross-section data positions the first level, here denoted X-P1, at an optical excitation energy of 0.55 eV. The second level, denoted X-P2, is positioned at about 0.8 eV. The 0.55 eV energy obtained from the fitting procedure is in good agreement with Hall measurements of the activation energy of the carrier concentration for low P-doped samples. SIMS measurement shows a concentration of about 1 part per million (ppm) of phosphorus in the film. (C) 1999 Elsevier Science S.A, All rights reserved.