On the origin of white light emission from nanostructured silicon carbonitride thin films

The effects of thermal annealing on the visible luminescence of hydrogenated silicon carbonitride (SiCxNy:Hz) thin films were investigated. Thin films of a-SiC1.2N0.7:H1.4 were grown using electron cyclotron resonance plasma enhanced chemical vapor deposition and subsequently were annealed between 400 and 1200°C for 1h in nitrogen gas. The samples exhibited a broad luminescence band, covering the visible range with two dominant peaks at ~ 470 and 550nm, which appeared “white” to the naked eye. This white light emission could be deconvoluted into four photoluminescence (PL) bands. To understand the origin of PL from this complex material, two fairly well-studied submatrices, SiC:H1.3 and SiN1.3:H0.3, were also investigated. Our findings showed that the intensity of the PL emission of a-SiC1.2N0.7:H1.4 was higher than that of the binary matrices and was achieved at an optimized annealing temperature of 500°C. Carbon-related silicon defect centers were suggested as the sources of the luminescence of the a-SiCxNy:Hz thin films. The observed visible emission was strongly correlated with different Si-C bonding configurations.