Effect Of C/Si Ratio On Deep Levels In Epitaxial 4h-Sic

Changing the ratio of carbon to silicon during the epitaxial 4H-SiC growth is expected to alter the dominant deep level trap, which has been attributed to a native defect. The C/Si ratio was changed from one to six during epitaxial growth of SiC. Diodes fabricated on the epitaxial layer were then characterized using current-voltage and deep level transient spectroscopy. The single peak at 340 K (Z1/Z2 peak), was deconvolved into two traps, closely spaced in energy. The concentration of one of the Z1/Z2 traps decreased with increasing C/Si ratio. This result opposes theoretical predictions of carbon interstitial components, and supports assignment to a silicon antisite or carbon vacancy relationship. The concentration of the second component of the peak at 340 K did not depend on the C/Si ratio, which would indicate an impurity in an interstitial site.