Effect of RF Power on the Chemical Bonding and Humidity Sensing Properties of a-CNx Thin Films

Amorphous carbon nitride (a-CNx) thin films were deposited using radio frequency plasma enhanced chemical vapor deposition (rf-PECVD) technique. A set of a-CNx thin films were prepared using pure methane (CH4) gas diluted with nitrogen (N2) gas. The rf power was varied at 50, 60, 70, 80, 90 and 100 W. The characterization techniques used were Fourier transform infrared spectroscopy (FTIR) and field emission scanning electron microscope (FESEM). Humidity sensing properties of the a-CNx thin films were investigated by recording their electrical response to relative humidity (RH) at room temperature. Chemical bonding analysis clearly showed the presence of nitrile bands in the deposited films. The FESEM images of the films show a porous, granule-like and dendritic morphology. The average resistance of the a-CNx thin film is changed from 23.7 kΩ to 5.8 kΩ in the range of 5 to 95%RH. The films show a good response and repeatability as a humidity sensing materials. This work showed that rf power has a significant effects on the chemical bonding, morphology and electrical properties of the a-CNx films.

[1]  Guoliang Li,et al.  Titanium carbonitride coating by pulsed electrical discharge in an aqueous solution of ethanolamine , 2014 .

[2]  Koshi Adachi,et al.  Carbon tribo-layer for super-low friction of amorphous carbon nitride coatings in inert gas environments , 2013 .

[3]  S. Shiue,et al.  Effects of acetylene/ammonia mixtures on the properties of carbon films prepared by thermal chemical vapor deposition , 2013 .

[4]  Jun Xu,et al.  Effect of bombarding energy of N ions on composition, hardness and surface free energy of carbon nitride films , 2012 .

[5]  M. Othman,et al.  Effects of rf power on the structural properties of carbon nitride thin films prepared by plasma enhanced chemical vapour deposition , 2011 .

[6]  R. Di Mundo,et al.  Effect of Hydrogen on the Properties of Amorphous Carbon Nitride Films , 2011 .

[7]  R. Ritikos,et al.  Effect of Annealing on the Optical and Chemical Bonding Properties of Hydrogenated Amorphous Carbon and Hydrogenated Amorphous Carbon Nitride Thin Films , 2009 .

[8]  Xuemin Wang,et al.  Bonding structure and optical properties of a-CNx:H films deposited in CH4―NH3 system , 2009 .

[9]  R. Ritikos,et al.  Highly reflective nc-Si:H/a-CNx:H multilayer films prepared by r.f. PECVD technique , 2009 .

[10]  J. Kennedy,et al.  UV and humidity sensing properties of ZnO nanorods prepared by the arc discharge method , 2009, Nanotechnology.

[11]  Chi-En Lu,et al.  Humidity Sensors: A Review of Materials and Mechanisms , 2005 .

[12]  A. Liu,et al.  Prediction of New Low Compressibility Solids , 1989, Science.