Optical And Electrical Properties Study Of Sb?Mg Doped Tin Dioxide Thin Films

We report the photo-electrical properties of SnO₂:Sb and SnO₂:Mg thin films.Thesis is divided into two parts. Firstly, we systematicly reported the photo-electrical properties of SnO₂:Sb thin films with the increasing in antimony doping concentration. The XRD patterns revealed that all the samples posses tetragonal rutile structure. The absorption spectrum were tested in UV- visible wavelength range,the optical band gap can be estimated from the plot of??h??2 versus photon energy h?.As Sb concentration increases, the band gaps of the films vary. In order to futher study the effect of doping concentration on optical properties, photoluminescence spectra of the films were analysed in detail, with increasing Sb concentration in SnO₂,dominant visible light emission evolves into the ultraviolet regime in photo-luminescence. Doping concentration can impact crystalline quality and the structure of films, causing its electrical properties change with increase of the doping concentration.In this paper, the second part is related to the photo-electrical properties of the SnO₂:Mg films. According to our knowledge, no experimental report is available in the literature on the electrical properties on p-type doped SnO₂ nanoparticles till date.So we prepared SnO₂:Mg thin films and reported the structural and various photo-electrical properties. XRD measurements showed that all the diffraction peaks correspond to the rutile type tetragonal structure of SnO₂. From the absorption spectrum, the band gap becomes decrease with increase of the doping concentration.Mg substitution in Sn site may create two holes because of lower valence state of Mg2+ ion as compared to Sn4+ ion. Acceptor doping inducing the decrease of the band gap is attributed to the compensation of intrinsic donor to acceptor and the formation of impurity band. Hence band gap value may decrease. The Mg-doped SnO₂ films show a transform from n- to p-type conduction and theCarrier concentration of these samples exhibit decreases as Mg concentration increases, the highest carrier concentration of the SnO₂ sample has a value of 1.17×1013cm-3. It was observed from PL spectra that the PL intensity of the SnO₂:Mg increased up to 1 at% and then started to decrease with increasing doping concentration.