Study of Mn doping on the Structural, Optoelectronic and Photoluminescence Properties of F-Doped SnO<sub>2</sub> Sprayed Thin Films for Optoelectronic Applications

Abstract

The aim of this work is the production and the characterisation of (SnO2: (Mn, F)) thin films with appropriate optoelectronic properties required for application as ohmic contacts in photovoltaic application devices. Transparent conducting Manganese-fluorine co-doped tin oxide (SnO2: (Mn, F)) thin films have been deposited onto preheated glass substrates using the chemical spray pyrolysis (CSP) method. The ([Mn2+]/[Sn4+]) atomic concentration ratio (y) in the spray solution is varied between 0 and 8 at. %. The structural, the opto-electrical and the photoluminescence properties of these thin films have been studied. It is found that the deposited thin films are polycrystalline with a tetragonal crystal structure corresponding to SnO2 phase having a preferred orientation along the (200) plane. Transmission and reflection spectra reveal the presence of interference fringes indicating the thickness uniformity and the surface homogeneity of the deposited samples. Photoluminescence behaviour of Mn-F co-doped SnO2 thin films was also studied. Photoluminescence spectra reveal the presence of the defects like oxygen vacancies in the materials. In addition, The electrical resistivity, volume carrier concentration, surface carrier concentration and electrical mobility were determined from Hall Effect measurements and the following results were obtained: n-type conductivity in all the deposited thin films, a low resistivity of 1.50×10-4 Ω cm, and a high electrical mobility of 45.40 cm2 V-1 s-1 with Mn co-doping concentration equals to 7 at. %. These experimental results show that the electrical properties of these thin films where greatly improved making them suitable as ohmic contacts in photovoltaic applications devices.