Deep levels in n-type 4H-SiC epitaxial Schottky detectors by deep level transient spectroscopy and effects of edge termination on energy resolution

High resolution Schottky barrier alpha detectors have been fabricated on 20 μm n-type 4H-SiC epitaxial layers. The junction properties of the detectors were studied by current-voltage (I-V) and capacitance-voltage (C-V) measurements. A thermionic emission model applied to the forward I-V characteristic revealed an effective surface barrier height of 1.72 eV and a diode ideality factor of 1.18 suggesting uniform spatial distribution of surface barrier height. The C-V measurements revealed a doping concentration of 1.8×10¹⁴ cm^-3 which ensured a fully depleted (~20 μm) detector at bias voltages as low as ~70 V. Alpha spectroscopy measurements revealed an energy resolution of 0.5% for 5.48 MeV alpha particles. The performance of these detectors is limited by the presence of microscopic and macroscopic defects. Deep level transient spectroscopy (DLTS) studies revealed the presence of Ti(c), Z_½, and possible Ci1 defect centers. An improvement in detector resolution to ~0.3% was observed after edge termination while evaluating effects of surface defects on device performance.