Polycrystalline diamond thin film as wide bandgap material: the optoelectronic behaviour and the relationship with the structure

In this work metal-Microwave Plasma CVD diamond Schottky devices were studied. The current density vs. applied voltage reveals rectification ratios up to 10/sup 4/ at |/spl plusmn/2V|. Under illumination an inversion and increase of the rectification is observed. The carrier density is 10/sup 15/ cm/sup -3/ and the ideality factors near 1.5. The dark current vs. temperature shows that below 150 K the bulk transport is controlled by a hopping process with a density of defects of 10/sup 16/ cm/sup -3/. For higher temperatures an extrinsic ionisation with activation energy of 0.3 eV takes place. The correlation with the polycrystalline nature of the samples is reported.