The defects controlling carrier lifetime in 4H-SiC n- epilayers have been investigated by DLTS and time- resolved photoluminescence. Measurements of the dependence upon layer thickness enabled the separation of bulk and surface contributions to the measured lifetimes. Only the Z1/Z2 defect exhibited consistent correlation with measured lifetimes, while the EH6/EH7 defect was correlated only in some cases. The dependence upon layer thickness revealed a bulk minority carrier lifetime that was linearly related to the Z1/Z2 concentration and a hole capture cross-section of 3x10-14 cm2. This corresponded well to DLTS measurements carried out in p-i-n diode structures, where a large hole capture cross-section, sp, was indicated for Z1/Z2 and a small sp for EH6/EH7. Consequently, these results suggest that Z1/Z2 acts alone as the lifetime killer in this material.
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