Deep levels and conduction processes in nitrogen-implanted Ga2O3 Schottky barrier diodes

In this paper, we analyze the electrical behavior and the deep levels present in nitrogen-implanted gallium oxide Schottky barrier diodes annealed at increasing temperature from 800 degrees C to 1200 degrees C. In gallium oxide, nitrogen implantation is used in order to achieve controlled isolation of parts of the final device, and its stability and performance is therefore of high importance.The high temperature annealing carried out after implantation causes a reduction in the leakage current flowing in the structure, confirming the feasibility of nitrogen implantation as isolation procedure and the annealing of the defects caused by the implantation process.Repeated current-voltage measurements show the presence of an electron trapping process in the structure. The involved deep levels were investigated by means of isothermal transient spectroscopy tests, and both current and capacitance were used to monitor the trapping level in the devices. A model was developed to explain the full set of collected data on all the annealing temperatures, based on thermionic injection of electrons into an intermediate deep level and on charge injection into the space charge region.By means of deep level transient spectroscopy experiments we analyzed the various defects present in the samples. Their concentration correlates with the annealing, decreasing at high temperature. All the detected deep levels are consistent with previous reports in the literature, and are attributed to gallium vacancies, native point defects and extrinsic defects.