| The objectives of this dissertation work are to fabricate demonstrative SiC devices using ion-implantation and to study traps introduced into the SiC devices by the ion-implantation doping step. SiC, with its inherent material advantages like high band gap, high electric breakdown field, high saturation electron velocity and robustness, is an emerging material for fabricating high-power, high-temperature and high-frequency devices. Defect related traps could degrade the performance of SiC devices. For this reason, the results of this work are of interest to the SiC material and device research community.; In this work, fully implanted MESFETs were fabricated on semi-insulating (SI) 4H-SiC using phosphorus channel and nitrogen source/drain ion-implantations and characterized for their current-voltage (I-V) and capacitance-voltage (C-V) behavior. These devices showed a stable behavior even at 300°C. Also planar p+-n junction diode structures were fabricated using double-implantation technology on p-type SiC epitaxial layer. These diodes exhibited a high reverse leakage current (∼8 × 10 −2 A/cm2 at a reverse bias of 4 V) compared to the n+-p diodes due to high implantation damage.; Enhancement mode MISFETs, made on 6H-SiC p-type epilayer using nitrogen source/drain implantation (fabricated in collaboration with Yale University) and MESFETs, made on semi-insulating (SI) 4H-SiC using nitrogen dopant for the channel and source/drain implantations (fabricated by Dr. Jesse Tucker) were used for the capacitance DLTS characterization. For both of these devices, effective channel mobility is much smaller than the bulk mobility. For MESFETs five different traps were identified.; Transconductance dispersion measurements were performed on fully implanted MESFETs made on SI 4H-SiC using nitrogen implantation (by Dr. Jesse Tucker). A 30% reduction in the transconductance was observed for 0.1 Hz to 1 MHz frequency range. Bulk traps observed at 0.52 eV and 0.65 eV in the gated channel region, which were also seen in the capacitance-DLTS study, are believed to be due to the nitrogen implant-defect complex and vanadium deep donor dopant, respectively. Three surface traps in the ungated channel region between the source and gate and gate and drain were observed. (Abstract shortened by UMI.)... |
