Characteristics of the intrinsic defects in unintentionally doped 4H–SiC after thermal annealing

Thermal annealing effects on the characteristics of intrinsic defects in unintentionally doped 4H–SiC were investigated. The 4H–SiC samples were prepared by Low-Pressure Chemical Vapor Deposition (LPCVD) technique. Results show that there is only one Electron Spin Resonance (ESR) peak and a broad, from green to yellow, photoluminescence (PL) band were detected. These results are attributed to the native defects of carbon vacancy (VC) and complex carbon compound vacancy. The concentration of the intrinsic defects increases and reaches its maximum annealing at 1573 K, then decreases with the anneal temperature. Both ESR and PL have significant changes when the samples were annealed for 60 min. The concentration variation in unintentionally doped 4H–SiC is process dependent and is related to the interaction among the various intrinsic defects during the annealing. The silicon capping layer may also play an important role for these defect interactions particularly when the annealing was lasted for 60 min.