Date of Award
3-2002
Document Type
Thesis
Degree Name
Master of Science
Department
Department of Engineering Physics
First Advisor
James C. Petrosky, PhD
Abstract
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°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 °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°C may, in fact, enhance the rectifying device characteristics. Increasing the anneal temperature (TA = 1300°C) causes the device to fail entirely. Further annealing of the irradiated 4H-SiC at 1500°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.
AFIT Designator
AFIT-GNE-ENP-02M-03
DTIC Accession Number
ADA407869
Recommended Citation
Jones, Kent T., "Measurements of Neutron Induced Surface and Bulk Defects in 4H Silicon Carbide" (2002). Theses and Dissertations. 4506.
https://scholar.afit.edu/etd/4506