Fabrication and evaluation of AlN-SiC solid solutions with p-type electrical conduction

AlN-SiC solid solutions with p-type electrical conduction were fabricated with the addition of small amounts of Al and C. Powder mixtures of AlN and SiC with small amounts of Al and C (below 10 mol%) were consolidated by spark plasma sintering (SPS) at 2000°C for 10 min under 1 atm Ar, and then heat-treated at 2200°C for 3 h in an Ar flow to afford 2H AlN-SiC solid solutions. The relative densities of the 50AlN-50SiC-Al₄C₃ (A50-1AC) and 50AlN-50SiC-3Al₄C₃ (A50-3AC) samples were about 95%, whereas that of the 75A1N-25SiC-Al₄C₃ (A75-1AC) sample was about 86%. X-ray diffractometry (XRD) analysis showed that the samples comprised only the 2H phase, and except in the case of the A50-3 AC sample, no diffraction peaks of Al and C were observed. Although the samples without the additives (Al and C) were electrical insulators, addition of Al and C introduced p-type semiconduction. The electrical conductivities at 300°C of the A50-1AC and A50-3AC samples were about 30 and 100 S/m, respectively, whereas that of the A75-1AC sample was about 10^-1 S/m. It was found that addition of Al and C brought about electrical conduction in AlN-SiC solid solutions.