Gas Sensing Properties of Nanocrystalline Silicon Carbide Films: Experimental Results

Abstract

The effect of the air atmosphere on the electrical conductivity of nanocrystalline thin SiC films grown on sapphire using direct ion deposition was investigated. Gas sensitivity measurements were carried out on two series of nc-SiC films with different structures: the first series contained primarily 3C-SiC polytype nanocrystals and was designated as monopolytypic, while the second series was a nanoheterostructure based on a mixture of 3C-SiC and 21R-SiC nanocrystals. After annealing in vacuum at temperatures above 500 K, the films developed gas sensitivity. At a temperature of 700 K, measurements of the gas sensitivity of the films to the air atmosphere revealed that the resistance increased 12 times for the monopolytype film and nearly 16 times for the heteropolytype film. Purpose of the work: To experimentally investigate the dependence of electrical conductivity of thin nanocrystalline SiC films with different polytype structure on the air atmosphere at certain temperatures.