Deep Levels in n Type 4H Silicon Carbide Epitaxial Layers Investigated by Deep Level Transient Spectroscopy and Isochronal Annealing Studies
Deep levels were investigated by the capacitance mode deep level transient spectroscopy (C DLTS) on 4H SiC Schottky barrier diodes fabricated on 50 mm thick n type 4HSiC epitaxial layers. C DLTS scans from 80 K to 800 K revealed the presence of Ti(c) Z1/2, EH5, and EH6/7 defect levels in the energy range from 0.17 to 1.6 eV below the conduction band edge. The annealing out of primary defects and generation of secondary defects were investigated by systematic and thorough C DLTS studies from prior and subsequent isochronal annealing in the temperature range from 100 degC to 800 degC. The capture cross section of Ti(c) was observed to decrease up to 400 degC and remained unchanged at higher annealing temperatures. Defect densities were shown to decrease up to 200 degC and gradually increase at higher temperatures. The Z1/2 and EH6/7 defect parameters showed similar variation for the temperature range studied. The thermal evolutions of these deep levels in n type 4H SiC epitaxial layers are analyzed and discussed for the first time.
IEEE Transactions on Nuclear Science