SnO2: rGO transparent semiconducting thin films under annealing by hydrazine—modification of optical gap and electrical resistance

Abstract

In this paper, SnO₂: rGO compound thin films were deposited on glass substrates by spray pyrolysis method. For the synthesis of SnO₂: rGO thin films, different amounts of reduced graphene oxides (0, 25, 50, 75, 100, and 150 mg) were added to the solution. Then, the influence of reduced graphene oxide, and annealing by hydrazine as a reducing agent on the structural, electrical, and optical properties of these films were investigated. The results of XRD analysis in all the samples showed the SnO₂ phase is formed and the intensity of peaks increases relatively after reducing with hydrazine and increasing the value of rGO. FE-SEM images of SnO₂: rGO samples showed that grain size and porosity decreased after reduction with hydrazine. An enhancement of electrical properties was observed with the addition of reduced graphene oxide and annealing under hydrazine. The minimum sheet resistance equal to 0.42 kΩ/sq. for SnO₂: rGO (50 mg) thin films was obtained. The Hall effect experiment also showed the n-type conductivity of all synthesized thin films, and the carrier concentration was calculated to be 10²¹ cm⁻³. In addition, the band gap values of the films in the range of 3.58–3.72 eV were obtained and this method is a successful technique for tuning of the band gap of SnO₂ thin films.