Deep-level transient spectroscopy in the depletion zone of boron-doped homoepitaxial diamond films

Abstract

Abstract Investigation of deep levels in the depletion zone of boron-doped homoepitaxial diamond films is achieved from analysis of the transient responses of Schottky junctions. The active layer consists of a homoepitaxial film grown by microwave plasma decomposition of a very small percentage of B2H6 mixed with CH4 in hydrogen on synthetic Ib diamond substrates. Rectifying contacts are implemented with either aluminium, gold or erbium after suitable pre- and post-treatments. Reverse-current transients due to the thermal emission of holes from deep-level traps into the valence band are recorded and analysed with a Fourier transform deep-level transient spectroscopy (Fourier DLTS) procedure as a function of temperature up to 520°C. At each temperature, a thermal emission time constant is extracted. Arrhenius diagrams are deduced. A deep level at 1.40±0.07 eV above the valence band is detected in samples that have been submitted to a 800°C annealing in ultrahigh vacuum. Another deep level at 1.16±0.03 eV above the valence band exists only if an oxygen radio-frequency plasma treatment is applied to the sample before the Schottky contact deposition. Thermal capture cross-sections are also deduced.