Control of Electrical Resistivity in Silicon Carbide Ceramics Sintered with Aluminum Nitride and Yttria

Abstract

The electrical properties of β‐ SiC ceramics were found to be adjustable through appropriate AlN – Y 2 O 3 codoping. Polycrystalline β‐ SiC specimens were obtained by hot pressing silicon carbide ( SiC ) powder mixtures containing AlN and Y 2 O 3 as sintering additives in a nitrogen atmosphere. The electrical resistivity of the SiC specimens, which exhibited n ‐type character, increased with AlN doping and decreased with Y 2 O 3 doping. The increase in resistivity is attributed to Al ‐derived acceptors trapping carriers excited from the N‐derived donors. The results suggest that the electrical resistivity of the β‐ SiC ceramics may be varied in the 10 4 –10 −3 Ω·cm range by manipulating the compensation of the two impurity states. The photoluminescence ( PL ) spectrum of the specimens was found to evolve with the addition of dopants. The presence of N‐donor and Al‐acceptor states within the band gap of 3 C – SiC could be identified by analyzing the PL data.