Variations in the Effects of Implanting Al at Different Concentrations into SiC
SiC samples implanted at 600°C with 1018, 1019, or 1020 cm-3 of Al to a depth of ~ 0.3 μm and annealed with a (BN)AlN cap at temperatures ranging from 1300 – 1700°C were studied. Some of the samples have been co-implanted with C or Si. They are examined using Hall, sheet resistivity, CL, EPR, RBS, and TEM measurements. In all instances the sheet resistance is larger than a comparably doped epitaxial layer, with the difference being larger for samples doped to higher levels. The results suggest that not all of the damage can be annealed out, as stable defects appear to form, and a greater number or more complex defects form at the higher concentrations. Further, the defects affect the properties of the Al as no EPR peak is detected for implanted Al, and the implanted Al reduces the AlSi peak intensity in bulk SiC. CL measurements show that there is a peak near 2.9941 eV that disappears only at the highest annealing temperature suggesting it is associated with a complex defect. The DI peaks persist at all annealing temperatures, and are possibly associated with a Si terminated partial dislocation. TEM analyses indicate that the defects are stacking faults and/or dislocations, and that these faulted regions can grow during annealing. This is confirmed by RBS measurements.
Robert P. Devaty, David J. Larkin and Stephen E. Saddow
K. A. Jones et al., "Variations in the Effects of Implanting Al at Different Concentrations into SiC", Materials Science Forum, Vols. 527-529, pp. 831-834, 2006