Photoconductivity of undoped, nitrogen- and boron-doped CVD- and synthetic diamond

Fourier-Transform Photocurrent Spectroscopy of Defects in CVD Diamond Layers

“…[11], we can see a very good agreement in the positions of the photocurrent peaks at 303 and 347 meV and the optical absorption peaks of the first two excited states of the boron acceptor [12]. These are the collection levels for the effect of oscillatory photoconductivity, already observed in boron doped diamond films; the period being the LO photon energy [6]. This points to the presence of boron in some of our nominally intrinsic CVD diamond layers.…”

“…3 and 4 below 160 K with a structure strongly resembling the optical absorption spectrum of boron doped single crystalline or polycrystalline diamond [6,12], the second being the "opposite" temperature dependence of the threshold energy for a D x defect (below 1 eV) in Fig. 5, also seen above 160 K in Figs.…”

“…The photocurrent spectral measurements suffer from not well-specified surface conditions, from a low photosensitivity of this material, long term photocurrent drift and signal non-linearity [3][4]. Good agreement was found on oxidized samples only, when investigating the P1 defect (substitutional nitrogen) in the visible region, but IR photocurrent spectra depend heavily on the sample history and the surface treatment [5][6][7]. Here we present a spectroscopic approach, based on our recently developed Fourier-transform photocurrent spectroscopy FTPS [8] and on a careful control of the surface conductivity and photosensitivity of the hydrogen terminated diamond surface.…”

Structure due to indirect exciton in photocurrent spectrum of homoepitaxial diamond film

“…1. It is explained as due to carriers (electrons or holes) excited by the optical transition between deep states in the band gap and the conduction or valence bands [2]. The temperature evolution of the spectrum of i p (hn)/i p0 in the diamond CVD film B111, where the photocurrent obtained by deducting the photocurrent components due to the deep states from the observed photocurrent in Fig.…”

“…One of the reasons is in the fact that the thickness of the CVD film is too thin to measure the absorption spectrum in the low absorption coefficient range. In a diamond CVD thin film, instead, the photocurrent spectrum is used in order to obtain the information for the gap states and band edges [2].…”