Facile Route to the Controlled Synthesis of Tetragonal and Orthorhombic SnO₂ Films by Mist Chemical Vapor Deposition

Abstract

Two types of tin dioxide (SnO2) films were grown by mist chemical vapor deposition (Mist-CVD), and their electrical properties were studied. 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 (μ(FE)) values of approximately 3-4 cm(2)/(V s). On the other hand, orthorhombic SnO2 is found to behave as a metal-like transparent conductive oxide. Density functional theory calculations reveal 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.

Comparing electron- and hole transporting semiconductors in ion sensitive water- gated transistors

“…Precursors may be metal acetates, chlorides, or nitrates, processed by spin casting and later pyrolysis, or spraying directly onto hot substrates (spray pyrolysis) from solutions in polar solvents or water. Pyrolysis converts such precursors into semiconducting oxides such as ZnO, SnO 2 , TiO 2 , IGZO or In 2 O 3 [14][15][16][17][18]. These metal oxides lead to electron-transporting TFTs, while water-gated organic TFTs usually are hole-transporting.…”

Single crystalline SnO2 thin films grown on m ‐plane sapphire substrate by mist chemical vapor deposition

“…2, the SnO 2 surface morphology was much smoother than that of our previous result using the tin(II) chloride aqueous solution (not shown here). The reason for the obtained relatively flat surface morphology formed tin(II) acetate is not clear yet, though tin(II) chloride (SnCl 2 ) is often used as a source solution to grow SnO 2 by mist-CVD [9,18].…”

“…Second layer of SnO 2 films were overgrown on the single crystalline SnO 2 buffer layer at 800 ºC for 40 min. The source of the mist was changed to tin(II) chloride aqueous solution [9,18] with concentration of 2.5 mol/L. Figure 6 shows a top view SEM and AFM images of the surface of the second SnO 2 layer grown on the buffer layer.…”

“…In order to obtain high crystallographic properties of SnO 2 , the growth of single crystalline SnO 2 require relatively expensive film formation methods such as metalorganic chemical vapour deposition (MOCVD) [10] or molecular beam epitaxy (MBE) [12,13], which needs vacuum equipment. One alternative approach is a mist chemical vapour deposition (mist-CVD), which can form various oxide semiconductors under atmospheric pressure with a simple and less expensive technique [9,[14][15][16][17][18][19]. Most of the previous studies targeted SnO 2 film grown on c-plane and r-plane sapphire substrate even under vacuum condition (MOCVD, MBE and so on) and only few studies have focused on the film grown on other planes of sapphire [10].…”

Design of Reduction Process of SnO2 by CH4 for Efficient Sn Recovery

“…Sn (Tin) is a highly demanded industrial material 18 – 22 that is important for the production of electronics 23 – 26 , sensors 27 – 30 , glasses 31 – 33 , and displays 23 , 34 , 35 . The industrial demand of Sn is expected to gradually increase in the near future 20 – 22 as Sn plays as a central role in Pb-free solder 36 , 37 and transparent electrode 23 , 34 , 35 . The current London metal exchange market price of Sn is approximately $19,900/metric ton as of July 2017 38 , which is more than 3 and 10 times more expensive than Cu and Al, respectively 38 .…”