Effect of Nitrogen Doping on the Electrical Properties of 3C-SiC Thin Films for High-Temperature Sensors Applications

Abstract

3C-SiC is a promising structural material for piezoresistive sensors used in high-temperature applications. For sensor development, the preparation of sensor materials and study of its electrical properties, such as resistivity, barrier height of grain boundaries, and temperature coefficient of resistivity, are important in addition to structural properties and these have to be optimized. In the present work, 3C-SiC thin film with in situ doping of nitrogen is prepared through low-pressure chemical vapor deposition by using methyl trichloro silane, ammonia, and hydrogen as precursors. Electrical properties of deposited 3C-SiC thin films with varying nitrogen doping concentration through four probe technique are studied. Atomic force microscopy investigations are carried out to study the grain size on and average root-mean-squared roughness 3C-SiC thin films. A decrease in the degree of crystallinity is observed in nitrogen-doped 3C-SiC thin films. The sheet resistivity of nitrogen-doped 3C-SiC thin film is found to decrease with increase in temperature in the range from 303 to 823 K. The sheet resistivity, average temperature coefficient of resistance, and barrier height of the grain boundaries of film doped with 17 at.% of nitrogen are 0.14 Ω cm, −1.0 × 10−4/K, and 0.01 eV, respectively. Comparing all the nitrogen-doped 3C-SiC thin films, the film doped with 17 at.% of nitrogen exhibits an improved structural and electrical properties and it can be used as sensing material for high-temperature applications.