Gas sensing properties of nanocrystalline silicon carbide films

Abstract

Abstract The influence of the air atmosphere on the electrical conductivity of nanocrystalline thin SiC films obtained by method of direct ion deposition on sapphire was studied. Measurements were performed on two series of nc-SiC films with different structure: one series contained mainly 3C-SiC polytype nanocrystals and were denoted as monopolytypic, the second series were a nanoheterostructures based on a mixture of 3C-SiC and 21R-SiC nanocrystals. Gas sensitivity of the films appeared after annealing in vacuum at temperatures above 500 K. Measurements of the gas sensitivity of the films to the air atmosphere at a temperature of 700 K showed that the resistance increased for 12 times for the monopolytype film, while the heteropolytype film showed an increase of resistance for almost 16 times.

Keywords

• Silicon carbide based gas sensors
• Nanocrystalline silicon carbide film
• Air effect on electrical resistance
• Structure effect on air sensitivity