Transistor properties of exfoliated single crystals of2H−Mo(Se1−xTe<

Abstract

Field-effect transistors (FETs) were fabricated using exfoliated single crystals of Mo(Se 1−x Te x ) 2 with an x range of 0 to 1, and the transistor properties fully investigated at 295 K in four-terminal measurement mode. The chemical composition and crystal structure of exfoliated single crystals were identified by energy-dispersive x-ray spectroscopy (EDX), single-crystal x-ray diffraction, and Raman scattering, suggesting the 2H -structure in all Mo(Se 1−x Te x ) 2 . The lattice constants of a and c increase monotonically with increasing x, indicating the substitution of Se by Te. When x < 0.4 in a FET with a thin single crystal of Mo(Se 1−x Te x ) 2 , n-channel FET properties were observed, changing to p-channel or ambipolar operation for x > 0.4. In contrast, the polarity of a thick single-crystal Mo(Se 1−x Te x ) 2 FET did not change despite an increase in x. The change of polarity in a thin single-crystal FET was well explained by the variation of electronic structure. The absence of such change in the thick single-crystal FET can be reasonably interpreted based on the large bulk conduction due to naturally accumulated electrons. The μ value in the thin single-crystal FET showed a parabolic variation, with a minimum μ at around x = 0.4, which probably originates from the disorder of the single crystal caused by the partial replacement of Se by Te, i.e., a disorder that may be due to ionic size difference of Se and Te.

Recent progress on ambipolar 2D semiconductors in emergent reconfigurable electronics and optoelectronics

“…Graphene is a 2D material composed of carbon 128505-2 atoms, [56,57] which is the first widely studied ambipolar 2D material. So far, ambipolar behavior has been found in a variety of 2D materials, mainly in elemental materials and metal chalcogenide 2D semiconductors, [15] including elemental semiconductors like graphene, [57] phosphorene (BP), [58] silicene, [59] germanane, [60] tellurene, [61] and black arsenic; [62] metal disulfide 2D semiconductors like MoS 2 , [63,64] WS 2 , [65,66] ReS 2 , [67,68] and SnS 2 ; [69] metal diselenide 2D semiconductors like MoSe 2 , [70,71] WSe 2 , [72][73][74] ReSe 2 , [67] PtSe 2 , [75,76] and PdSe 2 ; [77][78][79] metal ditelluride 2D semiconductors like MoTe 2 , [80,81] and WTe 2 ; [82,83] ternary and other chalcogenide 2D semiconductors like Mo(Se 1−x Te x ) 2 , [84] W(Se 1−x Te x ) 2 , [85] SnSe, [86] SnS, [87] InSe, [88] InSb, [89] Cr 2 S 3 , [90] Nb 2 SiTe 4 , [91] and (Bi x Sb 1−x )Te 3 . [92] In addition to the aforementioned inorganic 2D materials, some organic 2D materials also exhibit similar properties.…”

Ambipolar 2D Semiconductors and Emerging Device Applications

“…[51] Besides WSe 2(1−x) Te 2x , the ambipolar behavior was also observed in MoSe 2(1−x) Te 2x and Nb 2 SiTe 4 . [204][205][206] It is worth noting that the polarity seems dependent on the component. With different element concentrations, the polarity was tuned from P-type, ambipolar, to N-type.…”

“…With different element concentrations, the polarity was tuned from P-type, ambipolar, to N-type. [204] Many new metal chalcognides have arisen with the rapid growth and deepening studies of 2D MDCs. Among these materials, several products have been verified to be of ambipolar semiconductors.…”

“…With different element concentrations, the polarity was tuned from P‐type, ambipolar, to N‐type. [ 204 ]…”