Growth of Alloy MoS_2xSe_2(1–x) Nanosheets with Fully Tunable Chemical Compositions and Optical Properties

Abstract

Band gap engineering of atomically thin two-dimensional layered materials is critical for their applications in nanoelectronics, optoelectronics, and photonics. Here we report, for the first time, a simple one-step chemical vapor deposition approach for the simultaneous growth of alloy MoS2xSe2(1-x) triangular nanosheets with complete composition tunability. Both the Raman and the photoluminescence studies show tunable optical properties consistent with composition of the alloy nanosheets. Importantly, all samples show a single bandedge emission peak, with the spectral peak position shifting from 668 nm (for pure MoS2) to 795 nm (for pure MoSe2), indicating the high quality for these complete composition alloy nanosheets. These band gap engineered 2D structures could open up an exciting opportunity for probing their fundamental physical properties in 2D and may find diverse applications in functional electronic/optoelectronic devices.

Booming Development of Group IV–VI Semiconductors: Fresh Blood of 2D Family

“…Ternary alloys have attracted intensive attention in recent years due to the varied properties through doping the third elements into the pure binary systems, which may provide an important versatility in low‐power consumption electronics and optoelectroncis 189, 190, 191, 192, 193, 194. For example, Pb 1–x Sn x Se is a narrow direct bandgap semiconductor with promising applications in mid‐infrared photodetection (1–3 μm), topological crystalline insulators and high‐speed logic devices due to the doping of Pb 104, 107, 195, 196.…”

Two-dimensional inorganic analogues of graphene: transition metal dichalcogenides

“…The organic coating promotes the growth of MoS 2 layers by wetting of the growth surface and lowering the free energy for nucleation [50]. Ternary MoS 2x Se 2(1−x) nanosheets with tuneable band edge emission have been obtained by Li et al [45] by a similar vapour-phase reaction of MoO 3 with sulfur and selenium powders (figure 4d and e). Few-layer MoS 2 has been grown on a graphitic surface by the thermal reduction of amorphous MoS 3 in the presence of reduced graphite oxide at 1000 • C under high-vacuum conditions [51].…”

“…The substrates were placed in a cold zone at 650 • C [46]. Feng et al [52] have also reported the synthesis of uniformly distributed monolayer MoS 2(1−x) Se 2x alloys on SiO 2 /Si substrates through the direct evaporation of MoSe 2 [44], (d,e) adapted with permission from Li et al [45], (f ,g) adapted with permission from Wu et al [46] and (h) adapted with permission from Liu et al [47].…”

Ultrafast, Broadband Photodetector Based on MoSe2/Silicon Heterojunction with Vertically Standing Layered Structure Using Graphene as Transparent Electrode

“…As one of the most significant members of 2D materials family, transition metal dichalcogenides (TMDs), such as MoS 2 , MoSe 2 , WS 2 , and WSe 2 , have attracted tremendous attention currently due to their outstanding electronic, optical, and mechanical properties 11, 12, 13, 14, 15, 16, 17, 18, 19. Monolayer MoSe 2 is a sandwich structure consisting of one Mo atom and two Se atoms, and the different layers are interacted by van der Waals force 20, 21.…”

“…It has been proved that MoSe 2 can absorb nearly 5%–10% of incident sunlight in a thickness less than 1 nm 26. Moreover, bandgap engineering on MoSe 2 could be accomplished by forming ternary alloy of MoS 2(1– x ) Se 2 x 17, 27, 28. Owing to these appealing properties, many efforts have been devoted to exploit the applications of MoSe 2 in diverse fields, including ion batteries, FETs, and photovoltaics, etc 29, 30, 31, 32, 33…”