The role of N_x-Si-O_y bonding configuration in acquiring strong blue to red photoluminescence from amorphous SiN_xO_y film

摘要

We report the acquisition of strong blue to red photoluminescence (PL) from a-SiN_xO_y thin film that was prepared by plasma enhanced chemical vapor deposition at room temperature. By increasing the flow rate ratio (R) of silane (SiH_4) to ammonia (NH_3), the luminescent peak position can be tunable in the visible range from 440 to 590 nm, and shown to be independent of temperature as revealed by temperature-dependent PL investigation. The Fourier transform infrared (FTIR) spectra and X-ray photoelectron spectra (XPS) were employed to clarify the relationship between the bonding configuration and PL characteristics. Based on the existence of N-Si-O bond arrangement evidenced in FTIR spectra, the deconvolution of the Si 2p peak was carried out to yield five component peaks corresponding to Si-N_4, N_3-Si-O, N_2-Si-O_2, N-Si-O_3, and Si-O_4. The increase of PL intensity is suggested to be closely related to increased concentration of N_x-Si-O_y bonds. All the results obtained from temperature-dependent PL spectra, FTIR spectra, and XPS spectra disclosed that the light emission from a-SiN_xO_y film can be originated from recombination via luminescent centers associated with N_x-Si-O_y bonding configuration, and the redshift of PL peak with the increase of R may arise from integral effect of N_x-Si-O_y bonding configuration transformation and valence band maximum upward shift.