On μτ product measurements in CVD diamond

Abstract

Energy-resolved steady-state and transient photocurrent measurements are investigated with the aim to evaluate the density of states (DOS) in CVD diamond films. The steady-state photocurrent spectra reflect the photoexcitation of carriers from two dominant defect structures in CVD diamond films which we denote as D1 and D2 levels [photoexcitation onsets at about 1.0 eV (D1) and at 2.1 eV (D2)]. The comparison of the photocurrent spectra with Ib diamond allows us to attribute the D2 level to the substitutional nitrogen. The D1 level remains unidentified. The mu*tau product increases for samples showing dominantly the D1 level photoexcitation. The transient photocurrent spectra obtained after laser pulse illumination in sandwich and coplanar configurations indicate an intense interaction of excess photo-carriers with a broad distribution of the DOS. (C) 1998 Elsevier Science S.A.