Characteristic defects in CVD diamond: optical and electron paramagnetic resonance study

Constant photocurrent method (CPM), electron paramagnetic resonance (EPR), and infra-red optical absorption (FTIR) techniques are used to study charac teristic defects in the gap of free-standing optical-quality CVD diamond. I t is shown that the gap density of states (DOS) is very sensitive to oxidat ion, hydrogenation and annealing treatments. The room-temperature (RT) EPR and CPM measurements reveal a well-defined single substitutional nitrogen d efect (P1). The photoionization energy of this defect is E-i = 2.2 eV. The presence of another defect state, denoted previously as D1 (E-i = 1.2 eV) i s discussed. This (D1) defect level is stable up to high annealing temperat ures. The changes observed in the EPR spectra after oxidation/hydrogenation are discussed. IR absorption in the CH-stretch band and in one-phonon abso rption regions is investigated. (C) 1999 Elsevier Science S.A. All rights r eserved.