Tin oxysulfide composite thin films based on atomic layer deposition of tin sulfide and tin oxide using Sn(dmamp)2 as Sn precursor

Abstract

Sn(II) dimethylamino-2-methyl-2-propoxy (Sn(dmamp)2) with water and hydrogen sulfide as oxygen and sulfur sources was employed in atomic layer deposition (ALD) of composite tin oxysulfide thin films abbreviated by Sn(O,S) made up of tin oxide (SnO) and tin sulfide (SnS) thin films employed as end members in addition to tin oxide and tin sulfide. Both SnO and SnS thin films demonstrate temperature-independent growth rates per cycle of 0.042nm/cycle and 0.056 nm/cycle, at 100–160 °C and 100–130 °C, respectively. Comparison of two tin-based thin film materials demonstrates dissimilar deposition features depending on the reactivity of the Sn precursors, i.e., Sn(dmamp)2 with anion sources provided by the water and hydrogen sulfide reactants. Density functional theory (DFT) calculations show that surface exchange reaction between *OH and *SH groups determine preference of S incorporation in the Sn(O,S) thin films. The material properties of ALD-based SnO, SnS, and Sn(O,S) thin films were characterized in terms of composition, stoichiometry, crystallinity, band structure, and electronic properties, demonstrating the potential of ALD SnO and SnS as p-type channel materials for transparent electronics.