COMPLEMENTARY SURFACE INVESTIGATION OF DIAMOND BY SCANNING THERMAL MICROSCOPY AND SCANNING NEAR-FIELD CATHODOLUMINESCENCE

Abstract

The interest in diamond windows for the application of high power radiation technology is increasing continuously due to its outstanding thermal and opto-electronic properties. In order to analyze the surface properties of very highly polished polycrystalline diamond in the sub-micrometer down to nanometer regime, two different near-field microscopy techniques have been employed. By using a Scanning Thermal Microscope (SThM) it is possible to uncover the varying thermal conductivity of different diamond grains. Dissimilar thermal surface properties within diamond grains have been measured with a resolution in the nm regime. Beside the fact of determining a small surface thermal conductivity compared to the well known data of bulk material, the thermal conductivity of inferior and superior diamond quality is separated quantitatively. Additionally the opto-electronic properties of the polished diamond have been investigated by Scanning Near-Field Cathodoluminescence (NF-CL). This measurement technique allows the detection of the distribution of dislocations within diamond grains with a resolution of less than 100nm. The comparison of these results, obtained by SThM and NF-CL, demonstrates a fine alignment in representing crystal lattice imperfections.