Characterization of the Optical and Electrical Properties of Proton- Irradiated 4H-Silicon Carbide

Epitaxial n-type 4H-silicon carbide (SiC) is irradiated with 2 MeV protons to evaluate the dislocation damage effects on the optical and electrical characteristics of the material. The optical properties of the material are investigated using temperature-dependant photoluminescence (PL) and the effects of proton irradiation on the electrical properties are evaluated using current- voltage measurements and constant-voltage deep level transient spectroscopy (CV- DLTS). Subsequent high-temperature thermal annealing and recovery of the irradiated material is investigated over the temperature range of 900-1500 deg C. Proton-induced irradiation damage is apparent in the 4H-SiC material, affecting both the optical and electrical characteristics of the devices. The radiative behavior of the nitrogen-related near band edge transitions is significantly reduced as a result of the irradiation with partial recovery observed after high-temperature thermal annealing at 1500 deg C. A deeper trapping complex (EC-ET 380 meV) is detected as a result of irradiation and shows signs of activation due to thermal annealing. Initial indications taken from I-V measurements of the Schottky diodes reveal that proton irradiation followed by thermal annealing at 900 deg C may, in fact, enhance the rectifying device characteristics. Increasing the anneal temperature (TA = 1300 deg C) causes the device to fail entirely. Further annealing of the irradiated 4H-SiC at 1500 deg C demonstrates recovery in the rectifying behavior of the material. Significant levels of deep level donor traps are observed, induced by irradiation in n-type material. Three detectable defect pairs emerge with energy levels ranging from 570-730 meV below the conduction band. The trap parameters were determined using curve-fitting algorithms.Air Force Inst of Tech Wright-Patterson AFB OH School of Engineering and Management is the author of 'Characterization of the Optical and Electrical Properties of Proton- Irradiated 4H-Silicon Carbide', published 2002 under ISBN 9781423506751 and ISBN 1423506758.