Electrical characterization of ion-implanted n(+)/p 6H-SiC diodes

In this work the electrical characterisation of ion implanted n(+)/p planar SiC diodes is presented. When a silicon dioxide film passivated the surface, the presence of electrically conductive paths among the cathodes of the diodes were detected. Surface morphology investigations and Electron Beam Induced Current (EBIC) analyses allowed us to correlate the conductive paths with grooves induced on the SiC surface by the post implantation annealing. After removing the surface silicon oxide film, the diodes were electrically isolated and their current-voltage (I-V) and capacitance voltage (C-V) characteristics were evaluated. At 10 V the best diodes 2 had a leakage current density value lower than 5x10(-11) A/cm(2) while some other diodes showed a value higher than 1x10(-7) A/cm(2). EBIC analyses pointed out a similar defect situation in the base region independently of the leakage current value. So no evidence of a correlation between the presence of electrically active defects and the leakage current behavior was found. The maximum measured value of the breakdown voltage (V-B) was of about 280 V. For the best diodes, the ideality factor was 2.1 at low voltages and then reached 1.4 increasing the forward bias, but never got 1 before the series resistance dominated the characteristic. Base and emitter doping concentrations calculated using C-V measurements were in agreement with the expected values.