Multi-phase structured hydrogenated amorphous silicon carbon nitride thin films grown by plasma enhanced chemical vapour deposition

Abstract

In this work, hydrogenated amorphous silicon carbon nitride (a-SiCN:H) films were grown by plasma-enhanced chemical vapour deposition (PECVD) process using SiH4, CH4 and N2 gas discharge. The effects of N2 flow-rate on the structure, optical as well as photoluminescence properties were investigated. AES depth profile and FTIR spectroscopy analysis were used to probe the distribution of elemental composition and the bonding configuration within the film structure respectively. As a complement, Raman analysis were done to investigate the presence and properties of the amorphous carbon phases within the films. The films grown on both c-Si and glass substrates were multiphase in structure with dominant component of a-SiCN:H, a-SiC:H and a-CN:H phases. Optical spectrophotometer measurements indicated that the band gap energy was dependent on the dominant phase present in the film structure and the overlapping of the tail states within the band gap, contributed to the low ETauc values of the films. The origin of the most dominant PL emission from the films was shown to be contributed by radiative transition and recombination within the band tails of the sp2-C clusters within the film structure.