Investigation of Defect Levels of Al/Ti 4H-SiC Schottky structures by Deep Level Transient Spectroscopy

The performance of silicon carbide bipolar devices is limited by the material quality of substrates and epitaxial layers. There are many aspects, one of which is the deep level defects in the epitaxial layer, that affect the quality of materials. N-type 4° off-axis Si-face silicon carbide epitaxial layers were investigated by deep level transient spectroscopy (DLTS), which includes C-V/I-V measurement, DLTS signal spectrum measurement and Arrhenius fitting analysis processes. The energy level position, concentration and capture cross-section of the deep level defects were obtained accurately after the measurement and analysis. Z
_1/2
defect was found to be a dominant deep level for all the as-grown samples because it existed in all the samples we characterized. So Z
_1/2
defect is widely distributed on epitaxial layers. The largest defect concentration in all samples is Z
_1/2
defect, which means that it was obviously the most influential defect type in this work. In addition to Z
_1/2
defects, three other deep levels had been found which were RD
_1/2
, EH
₅
and the one with defect energy level position near 1.209eV.