Disorder induced conductivity enhancement in SHI irradiated undoped and N-doped 6H-SiC single crystals

• Published in: Journal of materials science. Materials in electronics 2016-11, Vol.27 (11), p.11825-11833
• Main Authors: Sivaji, K., Viswanathan, E., Sellaiyan, S., Murugaraj, R., Kanjilal, D.
• Format: Article
• Language: English
• Subjects: Characterization and Evaluation of Materials; Chemistry and Materials Science; Crystal defects; Disorders; Electronics; Impedance; Irradiation; Materials Science; Optical and Electronic Materials; Spectra; Time constant; Trapping
• ISSN: 0957-4522; 1573-482X
• DOI: 10.1007/s10854-016-5323-6

We have studied undoped and N-doped 6H-SiC in its pristine and swift heavy ion (SHI) irradiated (150 MeV Ag 12+ 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 (σ dc ) 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.