Elaboration and characterization of SnO2:In thin films deposited by spray pyrolysis technique

Abstract

In this work, we have used the ultrasonic spray technique to deposit thin films of undoped and doped SnO2 on glass substrates. To optimize the quality of SnO2 thin films, we have studied the influence of molarity, deposition time and substrate temperature on film’s physical properties.The other aim of this work is to optimize the quality of these films by studying the influence of the dopants, the annealing temperature and the type of precursor of the starting solution on the structural, optical and electrical properties in order to obtain transparent and conductive films. For this reason, we used indium as a dopant and two types of the precursor of the starting solution (SnCl2.2H2O, SnCl4.5H2O).We used several characterization techniques, such as X-ray diffraction, UV-visible spectroscopy, scanning electron microscopy, Hall Effect and the four-point technique. We have shown that undoped and doped SnO2 films are transparent in the visible range and their structure is of tetragonal type. In our work, we found that the undoped SnO2 film deposited at 450° C for 5 minutes of deposition at a concentration of 0.1 mol / l has good properties. Also, indium-doped SnO2thin films with the best properties can be prepared using SnCl4 as a precursor and at the 2% and 20% doping rate. Also, Hall Effect measurement revealed that the undoped and doped films with 10% In had n-type electrical conductivity, and when it was at 20%, In-doped SnO2 thin films showed a p-type conductivity.The results showed that the process of annealing leads to the improvement of the crystallinity, the optical and electrical properties of SnO2.In films.