Optical properties of carbon nitride thin films fabricated by rapid chemical vapor deposition

Abstract

Developed rapid chemical vapor deposition lasting only 3 min allowed to produce smooth layered carbon nitride polycrystalline thin films as thick as 830–1547 nm at 550–625◦ C in air with crystallites in the layers oriented parallel to the substrate (glass or silicon) surface. They are distinguished by high transparency in the visible range and the thickness uniformity. It made possible an adequate optical transmission and absorption spectra measurements at room temperature and their correct processing with the Swanepoel's envelope method to determine optical properties of the films and compare them with characteristics of carbon nitride materials obtained by conventional chemical vapor deposition or thermal polymerization. The application of the Swanepoel's method allowed to determine actual thickness of the films and then the refraction index of the material to be 2.50–3.25 and the extinction coefficient to be 0.1–0.4 as functions of the deposition temperature. The average photoluminescence lifetime of the deposited material is found to be 2.3–2.6 ns for high energy carrier recombination processes being the shortest in the sample fabricated at 550◦ C and correlating with crystallinity of the film. Optimal temperature for rapid chemical vapor deposition of carbon nitride thin films is concluded to be in the range of 550–575◦ C providing its best properties promising for electronic and optoelectronic applications.