Simple Process to Control Crystalline for Tetragonal and Orthorhombic SnO2 Thin Film by Mist Chemical vapor Deposition

Abstract

Recently, oxide thin films have been investigated for its various use in semiconductor, insulator and conductor. Especially oxide semiconductors have its characteristics of low cost, high mobility and transparency which can be strongly considered as an alternatives of a-Si and poly-Si thin film transistors (TFTs) for TFT-LCDs and AMOLEDs. Among the various materials, tin oxide (SnO2) is a promising material for its high mobility. In this paper we have investigated tin oxide thin film that was fabricated by mist chemical vapor deposition (Mist-CVD). Mist-CVD is a solution based atmospheric pressure fabrication technology that has the advantage of low cost and good uniformity. Two different types of crystalline tin dioxide (SnO2) thin films were grown to study the electrical properties. Both types of Tin dioxide (SnO2) thin films were fabricated by dissolving tin(II) chloride dihydrate (SnCl2·2H2O, Aldrich) in two different solvents. A tetragonal phase is obtained when methanol is used as the solvent, while an orthorhombic structure is formed with acetone. The two phases of SnO2 exhibit different electrical properties. Tetragonal SnO2 behaves as a semiconductor, and thin-film transistors (TFTs) incorporating this material as the active layer exhibit n-type characteristics with typical field-effect mobility (μFE) values of approximately 3−4 cm2/(Vs). On the other hand, orthorhombic SnO2 is found to behave as a metal-like transparent conductive oxide. It is suggest that orthorhombic SnO2 is more stable under oxygen-rich conditions, which correlates well with the experimentally observed solvent effects. The present study paves the way for the controlled synthesis of functional materials by atmospheric pressure growth techniques.