Disorder induced conductivity enhancement in SHI irradiated undoped and N-doped 6H-SiC single crystals
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We have studied undoped and N-doped 6H-SiC in its pristine and swift heavy ion (SHI) irradiated (150 MeV Ag12+ ions) forms by impedance spectroscopy at low temperatures. Fitting analysis of the complex impedance spectra reveals two time constants (R 1 Q 1 and R 2 Q 2) for the irradiated samples and single time constant (R 1 Q 1) for the pristine undoped and N-doped samples. This indicates a decrease in the grain interior conductivity (σdc) for the irradiated undoped 6H-SiC and an increase for the N-doped samples. The increased conductivity in the irradiated N-doped samples is due to the possibility of defect trapping and by the defect. The Activation energy (E a) exhibited an increase in the undoped samples and decrease in the N-doped samples. The σ dc and the E a results suggest that the (de-)trapping effect on the defect states is significant in the irradiated samples. Furthermore, the impedance results support the formation of homogenous/heterogeneous defect structures in the irradiated samples. Impedance studies also reveals the disappearance of the charge carriers due to the (de-) trapping at the defect states at damage zone interface (DZI). The presence of disorder and the nature of the disorder are discussed.
KeywordsCharge Carrier Irradiate Sample Defect State Undoped Sample Electrical Modulus
The authors gratefully acknowledge the support of Inter University Accelerator Centre (IUAC), New Delhi for providing the Accelerator facility and financial support in the form of a Junior Research Fellowship to E.V. (UPUF-39306). The author KS gratefully acknowledge the National Centre for Nanoscience and Nanotechnology (NCNSNT), and DST PURSE program of University of Madras for the financial support.
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