Effect of Iodine-doping toward ZnO critical optical constants and their applications to latent fingerprints detection

Abstract

The present work focus on the influence of Iodine (I) doping on the improvement of properties of ZnO such as structural, optoelectronic, optical, dielectric and transport. I-doped ZnO materials were synthesized via an easy sol gel method assisted by microwave post-heated treatment. I doping level was 0, 0.025, 0.050, 0.075, and 0.100 at% with respect to Zn content. The deducted physico-chemical properties were based on XRD, Raman spectroscopy, EDS, XPS, SEM imaging, photoluminescence (PL) and UV-Visible diffuse reflectance (UV-Vis DRS) spectroscopy. The prepared nanomaterials were applied to latent fingerprints detection. The determined optical constants were based on diffuse reflectance data and consequently the refractive index and extinction coefficient. Tauc’s equation was used to evaluate both band gaps and inter-band transitions as impacted by doping. The dielectric properties, optical and electrical conductivities dependence on both frequencies and I-doping level were studied. Dissipation loss factors including surface and bulk contributions were evaluated. The dynamics of transport with the consideration of the four components dielectric relaxation time (τ), optical resistivity (ρopt), optical mobility (μopt), and optical charge carriers (Nopt), were discussed in terms of photons energy assessment and materials composition. The optical covalency and optical electronegativity modification were considered. IxZnO nanomaterials were applied successfully to fingerprint detection on various substrates such as glass surfaces, coins, and plastic sheets. Both I0.025ZnO and I0.1ZnO materials were identified as a potential candidate for forensic application.