Research On Preparation Of Silicon Carbonitride Thin Films And Photoluminescent Properties

Thin silicon carbonitride (SiCN) films show an interesting combination of optical, electrical and mechanical properties, so it is promised that it will play a wide range of applications in the field of microelectronics and opto-electronics. SiCN thin films are proposed as candidates for luminescent application due to their extraordinary luminescent properties and adjustable band gaps varying from UV to visible light range.In this research, a series of SiCN films with different composition were deposited by radio-frequency reactive sputtering by changing the flow rate of N2, then annealed under different conditions. The photoluminescent (PL) properties were studied, and TEM, EDS, XRD, XPS, FTIR were adopted to investigate the structure and bond types in this research.It was found that using hydrogen as the protective gas is an effective method in the course of annealing compared with argon and nitrogen gas. Ultraviolet (UV) and visible light emit from Si27.64C15.77N49.63O6.96 film annealed at 1200℃in hydrogen gas. The UV luminescence is attributed to defects in Si-O network, while the visible light is relate to the quantum confinement effect in crystalβ-SiC phase.Si_34.7C_26.5N₂₅O_13.8 film shows ultraviolet and visible light emission after annealed at low temperature in nitrogen gas with low pressure. The UV luminescence is also attributed to defects in Si-O network, while the visible light is related to the formation of carbon sp² bonds in C-N areas, respectively.In addition, the changes on PL properties of SiCN films sputtered by the increased flow rate of N₂ and annealed at the same temperatures are analyzed. It was found that the PL intensity of the sample, which was deposited by the middle flow rate of N₂, is high than the other four samples. It indicates that the chemical composition of this sample is propitious to photoluminescence.