Fabrication and assessment of sputtered Si:SiO2 films emitting white light without annealing

Without annealing, we fabricated sputtered Si:SiO2 films that emit white light and assessed the optical characteristics. such as photoluminescence (PL) spectra, transmittance, absorption edge, and refractive indexes. Si:SiO2 films were deposited by sputtering Si tablets (20 mm diameter) onto a SiO2 target (65 mm diameter). By performing annealing experiments we found that our samples were not uniform SiOx but consisted of Si-rich regions dispersed as clusters in SiO2 medium. Samples deposited using one or two tablets exhibited wide continuous PL spectra (from wavelengths below 0.38 mum to over 0.83 mum) with two broad peaks, and white-light emission could be seen by the naked eye at room temperature, The peaks of the higher energy PL band seemed to agree relatively well with the band edges, which implies the contribution of the quantum confinement effect of Si clusters. Samples deposited using three or four tablets did not emit, and we found there was a limited Si mixture ratio at which samples emit without annealing.