Optical Characteristics of Amorphous Tin Nitride Thin Films Prepared by Ion Beam Assisted DC Magnetron Reactive Sputtering
Abstract
This work reports the preparation of thin films of amorphous tin nitride (a-Sn:N) by a novel implementation of simultaneous ion beam assisted deposition (IBAD) and reactive DC magnetron sputtering of a metal tin target in pure nitrogen plasma. The work also reports the optical characterization and determination of the optical constants of a-Sn: N thin film material. The refractive index n varies only slightly over the spectral range of 400-900 nm while the extinction coefficient k displays a gradual but significant increase starting at ~470nm. We have estimated the optical energy gap, Eopt , to be 2.32 ± 0.047eV deduced from the transmittance measurements. Other important optical characteristics, such as the high frequency dielectric constant ε∞, the average oscillator’s wavelength λο, the average oscillator strength Ѕο, tangent loss (tan δ) and the optical conductivity σ, are also determined. Determination and interpretation
of some of the optical properties are based on the single oscillator model proposed by Wemple and DiDominico.
Keywords: Amorphous Materials, Reactive Sputtering, Ion Beam Assisted Deposition (IBAD), Thin Films, Optical Properties.
