Mythili Surendran1,Shantanu Singh1,Huandong Chen1,Boyang Zhao1,Jayakanth Ravichandran1
University of Southern California1
Mythili Surendran1,Shantanu Singh1,Huandong Chen1,Boyang Zhao1,Jayakanth Ravichandran1
University of Southern California1
Chalcogenide semiconductors, especially 2D transition metal dichalcogenides, are extensively studied owing to their intriguing physical properties for electronic and photonic applications. However, in the past few years, ternary chalcogenide semiconductors such as chalcogenides perovskites have gained substantial interest as a new class of semiconductors due to their tunable chemistry, structure, and opto-electronic properties. For instance, BaZrS<sub>3</sub> (BZS) (band gap = 1.9 eV), a prototypical chalcogenide perovskite, is promising as an ultra-thin absorber in tandem solar cells<sup>1-3</sup>, whereas BaTiS<sub>3</sub> (BTS) (band gap = 0.27 eV) exhibits a giant birefringence and large optical anisotropy in the infrared region<sup>4</sup>. Growth of thin-film chalcogenide perovskites is a critical step to enable investigations into their fundamental properties and also device applications. But the thin-film growth of chalcogenide perovskites is challenging due to a large mismatch in the vapor pressure of the cations and chalcogens, corrosive and reactive nature of most chalcogen precursors, the propensity to oxidize easily in the presence of oxygen at high temperatures and the lack of suitable non-reactive substrate surfaces for epitaxial growth.<br/> <br/>Recently, we have demonstrated direct, single-step, epitaxial growth of BZS<sup>1</sup> and BTS<sup>5</sup> thin films on oxide substrates by pulsed laser deposition (PLD) using Argon-H<sub>2</sub>S background gas. H<sub>2</sub>S is a toxic, hazardous, and flammable gas and reacts with many materials, and the ionized Argon and/or H<sub>2</sub>S lead to significant degradation of the crystallinity of both the surface and film at the high growth temperatures. Here, we report an alternative hybrid PLD approach using organo-sulfur precursors as sulfurizing agents to grow chalcogenide semiconductors. To demonstrate the efficacy of this approach, we have demonstrated epitaxial growth of 3D binary chalcogenides such as BaS and SrS (wide band gap) and 2D binary chalcogenides such as TiS<sub>2</sub> (metallic) and ZrS<sub>2</sub> (semiconducting). The potential of these binary sulfides as suitable candidates for transparent and conducting layers in chalcogenide-based photovoltaic devices will be discussed. We have also realized epitaxial BZS and BTS films using hybrid PLD and a comparison of this approach to PLD using Ar-H<sub>2</sub>S will be provided. Further, we will also discuss our future growth efforts and the applications of this novel growth method.<br/> <br/>References:<br/> <br/>1. M. Surendran, H. Chen, B. Zhao, A. S. Thind, S. Singh, T. Orvis, H. Zhao, J.-K. Han, H. Htoon, M. Kawasaki, R. Mishra and J. Ravichandran, Chemistry of Materials <b>33</b> (18), 7457-7464 (2021).<br/>2. Y. Nishigaki, T. Nagai, M. Nishiwaki, T. Aizawa, M. Kozawa, K. Hanzawa, Y. Kato, H. Sai, H. Hiramatsu, H. Hosono and H. Fujiwara, Solar RRL <b>4</b> (5) (2020).<br/>3. S. Niu, H. Huyan, Y. Liu, M. Yeung, K. Ye, L. Blankemeier, T. Orvis, D. Sarkar, D. J. Singh, R. Kapadia and J. Ravichandran, Adv Mater <b>29</b> (9) (2017).<br/>4. S. Niu, G. Joe, H. Zhao, Y. Zhou, T. Orvis, H. Huyan, J. Salman, K. Mahalingam, B. Urwin, J. Wu, Y. Liu, T. E. Tiwald, S. B. Cronin, B. M. Howe, M. Mecklenburg, R. Haiges, D. J. Singh, H. Wang, M. A. Kats and J. Ravichandran, Nature Photonics <b>12</b> (7), 392-396 (2018).<br/>5. M. Surendran, B. Zhao, G. Ren, S. Singh, A. Avishai, H. Chen, J.-K. Han, M. Kawasaki, R. Mishra and J. Ravichandran, Journal of Materials Research <b>37</b> (21), 3481-3490 (2022).