Nanometer silicon carbide powder synthesis and its dielectric behavior in the GHz range

Abstract

Abstract In this paper, the dielectric properties of nano-sized SiC powders have been investigated in the GHz frequency range. The polytypes of SiC have been changed from β type (3C) to α type (12H and 21R) by varying the aluminum contents and the reaction atmospheres. The β-SiC powder has much higher relative permittivity ( e ′ r =30∼50) and loss tangent ( tgδ =∼0.7) than α-SiC powders. Though the doping of Al and N decrease the resistivity of SiC to the order of 10 2 Ω cm, the pivotal factor on the dielectric behaviors is ion jump and dipole relaxation, namely the reorientation of lattice defect pairs (V Si –V C , Si C –C si ). The conductivity of SiC has little effect on the dielectric behaviors.