Porous SiC for HT chemical sensing devices: An assessment of its thermal stability

Porous silicon carbide substrates produced by anodization that are intended for use in chemical sensing solid state devices that will operate at high temperatures (at or above 900°C) have been studied with a view to assessing the structural stability/pore modification processes occurring during thermal processing. Annealing experiments were performed using n-type porous 4H-SiC (PSiC) in the temperature range of 900°C-1700°C in Ar atmosphere. The samples were kept at the desired temperatures for 30 minutes. The morphology of the as-received samples consisted of well-oriented pores along the 〈041〉 direction. Significant pore modification occurred at 1400°C. The thickness of the porous layer was reduced following heating at 1700°C. The suitability of PSiC as a chemical sensing element is discussed.