SEZIONE DI FIRENZE
ABSTRACT: In the last years there has been a large increase in interest in diamond devices due to their properties, such as high radiation hardness, high carrier mobility, high thermal conductivity and high breakdown field. In particular, diamond devices are considered both performing sensors for detection and beam monitoring nuclear measurements and very functional power electronic devices working as p-n junctions and Schottky diodes. Anyway a crucial point for diamond devices is still opened: the manufacturing of ohmic and stable electrodes, which represents a huge task especially for intrinsic and lightly doped diamond films. Traditionally, the diamond contacting can be performed by two different techniques: the diamond graphitization and metallization. In this work, the laser-induced diamond graphitization process has been studied and successfully optimized for the production of ohmic graphitic contacts on a large scale diamond (20 × 20 mm 2 ) for nuclear applications as detector. This studied was carried out in the framework of a recent high-energy physics experiment proposed by the INFN and called Positron Annihilation into Dark Matter Experiment (PADME). By this way, the first all-carbon detector prototype has been successfully developed and tested with 450 MeV positron and electron beams provingto be a good candidate in the role of active target for PADME experiment. Afterwards, taking into account the promising results obtained on graphitic contacts, the graphitization technology was extended to the manufacturing of ohmic graphite/metal contacts on diamond for power electronic applications as Schottky diodes. In particular, the ion implantation-induced diamond graphitization process was optimized to induce a graphitic layer underneath the diamond surface, then the metallic pads micro-fabrication above a diamond mesa structure was performed to obtain a graphite/Ti/Au stack on the surface. The full contacting was developed on a sample representing a typical challenging electronic context, namely an oxygen-terminated lightly-boron doped diamond. As a result, the graphite layer proved to play a crucial role into the ohmic behavior of the electrodes. (Dr. Mary De Feudis)

DATA: 28-02-2019