Improved n-Type 4H-SiC Epitaxial Radiation Detectors by Edge Termination

A new edge termination with SiO2 and Si3N4 passivating layers has been developed and is shown to be a very effective method for improving energy resolution of 20 μm n-type 4H-SiC epilayer Schottky barrier radiation detectors. The junction properties of the fabricated detectors before and after edge termination were studied by current-voltage (I-V) and capacitance-voltage (C-V) measurements. A thermionic emission model applied to the forward I-V characteristics showed surface barrier height of ~ 1.4 eV and diode ideality factor of ~ 1.1. The C-V measurements showed 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 improved energy resolution from ~ 0.7 % to ~ 0.4% for 5.48 MeV alpha particles. Deep level transient spectroscopy (DLTS) measurements have shown a decreased concentration of Z1/2 defect levels in detectors following edge termination.