(Digital Presentation) Present Status and Future Prospects of Large Area Growth and Devices of Two-Dimensional Materials

Abstract

2D noble metal di- chalcogenides (NMDC or NMC) materials have attracted enormous research interests due to their novel physical and chemical properties with confined dimensions. Here we present two of our experimental works in investigating the growth of PtS and PtSx. (i) Platinum monosulfide as one of the most common platinum-group minerals has been less studied due to either the low purity in the natural product or the extremely high-pressure conditions for synthesis. Recently, platinum monosulfide (PtS) 2D membranes have emerged as rising-star materials for fundamental Raman and X-ray photoelectron spectral analysis as well as device exploration. However, a large-area homogeneous synthesis route has not yet been proposed and released. In this communication, we report a facile metal sulfurization strategy for the synthesis of a 4-inch wafer-scale PtS film. Enhanced characterization tools have been employed for thorough analysis of the crystal structure, chemical environment, vibrational modes, and atomic configuration. Furthermore, through theoretical calculations the phase diagram of the Pt–S compound has been plotted for showing the successful formation of PtS in our synthesis conditions. Eventually, a high-quality PtS film has been reflected in device demonstration by a photodetector. Our approach may shed light on the mass production of PtS films with precise control of their thickness and homogeneity as well as van der Waals heterostructures and related electronic devices. (ii) PtSx, as a more recent 2D material that aroused extensive research interests, has been applied in electronic and optoelectronic devices because of its excellent electronic characteristics and commendable stability. However, the synthesis of large-scale uniform PtSx remains a challenge. Here we studied a modified chemical vapor deposition (CVD) method to grow large-scale uniform PtSx films on SiO2/Si and c-plane sapphire substrates, which can avoid some disadvantages of the mechanical exfoliation method in the device fabrication. The large area uniform PtSx films are achieved through Pt sulfurization using H2S gas, replacing the sulfur powder in traditional methods, as the sulfur source. The material characterizations successfully proved that our modified CVD method is feasible and repeatable, and the PtSx film can be synthesized on different substrates. The PtSx photodevices show good photoresponse properties with a wide spectrum response range. The PtSx/sapphire device shows a better photoresponse in terms of the detectivity (9.17 × 109 Jones) and the responsivity (0.31 A W−1) than that of the PtSx/SiO2/Si device in our experiment, as well as one-year air stability, which may be caused by the different PtSx film quality due to a lattice mismatch difference between the PtSx and the different substrates. These results offer the design and synthesis technology for large-scale, uniform, and stable PtS and PtSx film, as well as an example of photoresponse-enhanced devices which could be generalizable to other transition metal dichalcogenides (TMDCs) and devices for future development and applications. Figure 1