Modification of electronic properties in insulators using ion microprobe

Development of techniques that use focused ion beams of MeV energy range for creation of new structures in materials by modifying their properties has been initiated in order to expand application possibilities of ion accelerators at the Ruđer Bošković Institute. In particular we have focused on heavy ions that create significantly larger radiation damage in materials when compared to protons and He ions. Structuring of radiation damage using the ion microbeam in crystalline materials has been developed and tested on silicon and diamond. Application possibilities of created structures came from the fact that radiation damage can decrease charge collection properties in silicon which may be of interest in production of position sensitive sensors. This approach has been demonstrated by creating position dependent response of silicon pin diodes. In the case of diamond, excessive radiation damage can increase conductivity which may be of interest for production of diamond based devices. Buried conductive lines have been produced in single crystal diamond. Additional application that use ion tracks created in different materials by heavy ion beams from 6.0 MV Tandem accelerator has also been developed. Application was first tested on polymers and subsequently on other materials of technological interest (such as SrTiO3). Cl and I ion beams of energies above 18 MeV have been used in this application. Implantation of lower energy ions such as carbon between 800 and 2000 keV has been performed also, using both broad and micro beam in order to form nanodiamonds in SiO2.