Formation mechanism of 2D SnS2 and SnS by chemical vapor deposition using SnCl4 and H2S. Issue 23 (21st May 2018)

• Record Type: Journal Article
• Authors: Zhang, Haodong; Balaji, Yashwanth; Nalin Mehta, Ankit; Heyns, Marc; Caymax, Matty; Radu, Iuliana; Vandervorst, Wilfried; Delabie, Annelies
• Is Part Of: Journal of materials chemistry. Volume 6:Issue 23(2018)
• Page Start: 6172
• Page End: 6178
• Publication Date: 2018-05-21
• Subjects: Materials -- Periodicals; Chemistry, Analytic -- Periodicals; Optical materials -- Research -- Periodicals; Electronics -- Materials -- Research -- Periodicals; 543.0284
• DOI: 10.1039/c8tc01821a
• Languages: English
• ISSNs: 2050-7526

Abstract

Abstract : Catalytic decomposition of H2 S by SnS2, with generation of H2, plays a critical role in the SnCl4 /H2 S CVD process. Abstract : SnS2 and SnS are two-dimensional (2D) semiconductors with distinct properties, as they exhibit a different type of conduction. They are of interest for applications in nanoelectronics, optoelectronics and sensors. To enable these applications, the deposition of SnS2 and SnS layers with a well-controlled phase, crystallinity and thickness at the nanometer level is required on large-area substrates. Chemical vapor deposition (CVD) of SnS2 and SnS using SnCl4 and H2 S has previously been reported to give micrometer level polycrystalline SnS2 and SnS layers, which were insulating due to the uncontrolled grain orientations. In this work, we investigate the formation mechanism and phase control of nanometer level 2D SnS2 and SnS by SnCl4 /H2 S CVD. Nanometer level and phase-pure 2D hexagonal SnS2 and orthorhombic SnS layers are obtained. The SnS x phase depends on both the temperature and the H2 S/SnCl4 concentration ratio. Compared to the formation of the SnS2 phase, the formation of the SnS phase is favorable at higher temperature and, surprisingly, at a higher H2 S/SnCl4 concentration ratio. This is explained by the catalytic decomposition of H2 S by SnS2 with the formation of H2, where the as such generated H2 reduces SnS2 to SnS at temperatures equal to or higher than 350 °C. By adjusting the conditions of the CVD process, the product can be tuned to either n-type SnS2 or p-type SnS, as demonstrated by back-gated field effect transistors.