Electrical properties of unintentionally doped semi-insulating and conducting 6H-SiC

• Published in: Journal of applied physics 2006-08, Vol.100 (4)
• Main Authors: Mitchel, W. C., Mitchell, W. D., Fang, Z. Q., Look, D. C., Smith, S. R., Smith, H. E., Khlebnikov, Igor, Khlebnikov, Y. I., Basceri, C., Balkas, C.
• Format: Article
• Language: English
• ISSN: 0021-8979; 1089-7550
• DOI: 10.1063/1.2227622

Temperature dependent Hall effect (TDH), low temperature photoluminescence (LTPL), secondary ion mass spectrometry (SIMS), optical admittance spectroscopy (OAS), and thermally stimulated current (TSC) measurements have been made on 6H-SiC grown by the physical vapor transport technique without intentional doping. n- and p-type as well semi-insulating samples were studied to explore the compensation mechanism in semi-insulating high purity SiC. Nitrogen and boron were found from TDH and SIMS measurements to be the dominant impurities that must be compensated to produce semi-insulating properties. The electrical activation energy of the semi-insulating sample determined from the dependence of the resistivity was 1.0eV. LTPL lines near 1.00 and 1.34eV, identified with the defects designated as UD-1 and UD-3, were observed in all three samples but the intensity of the UD-1 line was almost a factor of 10 more in the n-type sample than in the the p-type sample with that in the semi-insulating sample being intermediate between those two. OAS and TSC experiments confirmed the high purity of this material. The results suggest that the relative concentrations of a dominant deep level and nitrogen and boron impurities can explain the electrical properties in this material.