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CVD diamond has many outstanding physical properties. Because of its extreme hardness, this material is difficult to cut and polish and laser cutting and shaping is a technology of choice. Thick polycrystalline diamond layers were deposited by microwave plasma enhanced chemical vapor deposition on silicon substrates. After synthesis, the silicon substrate was dissolved in an acid mixture and diamond wafer has to be cut into desired shapes according to their future use. With LASAG Nd:YAG pulsed laser system KLS 246-102 we found cutting parameters for different thickness of diamond wafers from 0,1 mm to 0,7 mm. A special support with connection to vacuum was developed to keep small and light parts fixed during processing. To avoid undesirable cracks, laser scribing was used at first. Laser pulse with energy 30 mJ-200 mJ according wafer thickness and velocity 3mm.s-1-15 mm.s-1 goes two or four times along cutting lines. High temperature is the origin of black graphite layers, where absorption of laser radiation continues. Peak power contained in 0,2 ms pulse was up to 1000 W. Developed method helps to prepare CVD diamond samples of any desired shape.© (2005) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Optical absorption phenomena and in particular sub band gap absorption features are of great importance in the understanding of processes of charge generation and transport in organic pure and composite semiconductor films. To come towards this objective, an alternative and high sensitive spectroscopic approach is introduced to examine the absorption of light in pure and compound organic semiconductors. Because sub band gap absorption features are typically characterized by very low absorption coefficients, it is not possible to resolve them using common transmission and reflection measurements and high sensitive alternatives are needed. Therefore, a combination of photocurrent (Constant Photocurrent Method CPM/Fourier Transform Photocurrent Spectroscopy FT-PS) and photothermal techniques (Photothermal Deflection Spectroscopy PDS) has been used, increasing sensitivity by a factor of thousand, reaching detectable absorption coefficients ((E) down to 0.1 cm -1 . In this way, the dynamic range of measurable absorption coefficients is increased by several orders of magnitude compared to transmission/reflection measurements. These techniques have been used here to characterize ground state absorption of thin films of MDMO-PPV, PCBM and a mixture of both materials in a 1:4 ratio, as typically used in a standard active layer in a fully organic solar cell. The spectra reveal defect related absorption phenomena and significant indication of existing interaction in the ground state between both materials, contrary to the widely spread conviction that this is not the case. Experimental details of the techniques and measurement procedures are explained.