High-mobility three-atom-thick semiconducting films with wafer-scale homogeneity

Abstract

The large-scale growth of semiconducting thin films forms the basis of modern electronics and optoelectronics. A decrease in film thickness to the ultimate limit of the atomic, sub-nanometre length scale, a difficult limit for traditional semiconductors (such as Si and GaAs), would bring wide benefits for applications in ultrathin and flexible electronics, photovoltaics and display technology. For this, transition-metal dichalcogenides (TMDs), which can form stable three-atom-thick monolayers, provide ideal semiconducting materials with high electrical carrier mobility, and their large-scale growth on insulating substrates would enable the batch fabrication of atomically thin high-performance transistors and photodetectors on a technologically relevant scale without film transfer. In addition, their unique electronic band structures provide novel ways of enhancing the functionalities of such devices, including the large excitonic effect, bandgap modulation, indirect-to-direct bandgap transition, piezoelectricity and valleytronics. However, the large-scale growth of monolayer TMD films with spatial homogeneity and high electrical performance remains an unsolved challenge. Here we report the preparation of high-mobility 4-inch wafer-scale films of monolayer molybdenum disulphide (MoS2) and tungsten disulphide, grown directly on insulating SiO2 substrates, with excellent spatial homogeneity over the entire films. They are grown with a newly developed, metal-organic chemical vapour deposition technique, and show high electrical performance, including an electron mobility of 30 cm(2) V(-1) s(-1) at room temperature and 114 cm(2) V(-1) s(-1) at 90 K for MoS2, with little dependence on position or channel length. With the use of these films we successfully demonstrate the wafer-scale batch fabrication of high-performance monolayer MoS2 field-effect transistors with a 99% device yield and the multi-level fabrication of vertically stacked transistor devices for three-dimensional circuitry. Our work is a step towards the realization of atomically thin integrated circuitry.

MoS2-graphene in-plane contact for high interfacial thermal conduction

“…As a semiconductor with a direct bandgap (1.8 eV), monolayer MoS 2 is promising in electronic and photonic device applications, including transistors, light-emitters, photovoltaic and photodetectors. 3 With successful growth of MoS 2 on insulating substrates, 4 and significant improvement in its mobility at both low temperature and room temperature, 5−8 it is expected that high-performance fieldeffect transistors based on monolayer MoS 2 will be realized in the near future. In MoS 2 -based integrated devices, naturally, their thermal management will become vitally important.…”

Progress on Crystal Growth of Two-Dimensional Semiconductors for Optoelectronic Applications

“…Besides, the CVD process can be performed by solid-phase TMDC powder alone (as shown in Figure 3d-f), but the electrical and optical quality are not good enough [65]. In addition, as shown in Figure 3g-k, a high fabrication yield of (99.5%) for MoS 2 and WS 2 thin films was realized by Kang et al with good mechanical strength and film continuity on the basis of metal-organic chemical vapor deposition (MOCVD) [66]. The precursors used for MoS 2 and WS 2 thin films in their work were Mo(CO) 6 /(C 2 H 5 ) 2 S and W(CO) 6 /(C 2 H 5 ) 2 S, respectively.…”

Real-time monitoring of 2D semiconductor film growth with optical spectroscopy

“…A large amount of studies have been being carried out to grow large-area, high-quality, singlecrystal 2D-TMDs. Among these efforts, the technologies compatible with the existing microelectronic processes, such as chemical vapor deposition [9,10] and molecular beam epitaxy (MBE) [11][12][13][14][15][16][17][18][19][20][21], are receiving particular attention. On the other hand, real-time monitoring of the growth of 2D-TMD materials has seldom, if ever, been reported.…”