Nanopatterning and Electrical Tuning of MoS₂ Layers with a Subnanometer Helium Ion Beam

Abstract

We report subnanometer modification enabled by an ultrafine helium ion beam. By adjusting ion dose and the beam profile, structural defects were controllably introduced in a few-layer molybdenum disulfide (MoS2) sample and its stoichiometry was modified by preferential sputtering of sulfur at a few-nanometer scale. Localized tuning of the resistivity of MoS2 was demonstrated and semiconducting, metallic-like, or insulating material was obtained by irradiation with different doses of He(+). Amorphous MoSx with metallic behavior has been demonstrated for the first time. Fabrication of MoS2 nanostructures with 7 nm dimensions and pristine crystal structure was also achieved. The damage at the edges of these nanostructures was typically confined to within 1 nm. Nanoribbons with widths as small as 1 nm were reproducibly fabricated. This nanoscale modification technique is a generalized approach that can be applied to various two-dimensional (2D) materials to produce a new range of 2D metamaterials.

Robust photoluminescence energy of MoS2/graphene heterostructure against electron irradiation

“…3d). The creation of S vacancy is also reported by other particle irradiation approaches including He + [27] and Ar + irradiation [23,29]. Next we analyzed the Raman peaks of graphene in monolayer region and the heterostructure (Fig.…”

“…Defect engineering of materials, which can be achieved by irradiation of particles such as electrons or ions, provides an effective way to modulate properties of materials, as proven in silicon industry. Currently, diverse irradiation sources, including argon ions (Ar + ) [22,23], electrons [24][25][26], helium ions (He + ) [27][28][29], carbon ions [30] and oxygen plasma [31][32][33], have been utilized to bombard 2D materials. Irradiation could controllably introduce defects that strongly scatter phonons and electrons limited in the 2D surface, which generally degrades the intrinsic properties of 2D materials including mechanical strength [34], carrier mobility [23] and thermal conductivity [35].…”

Effect of ion irradiation on nanoscale TiS2systems with suppressed Titania phase

“…Tongay et al have used α-particle irradiation to generate vacancies in TMDCs, which give rise to new emission peaks with enhanced photoluminescence intensity [11]. Fox et al have demonstrated the use of a focused helium-ion beam to pattern MoS2 as well as preferentially sputter sulfur atoms [12]. The local tuning of opto-electronic properties of mono and few-layer TMDCs can provide an excellent opportunity to realize sharp homojunctions similar to conventional p-n, p-i-n, or p-n-p junctions, which are critical to many device architecture [8].…”

The co-design of interface sensing and tailoring of ultra-thin film with ultrasonic vibration-assisted AFM system

“…For instance, the bandgap of graphene becomes apparent once it has been tailored to the desired geometry [2,3]. The electrical and magnetic behaviors of MoS 2 , a graphene-like ultra-thin film material with two atomic layers, can be tuned by tailoring the crystal lattice parameters [4][5][6]. Black phosphorus exhibits a more noticeable in-plane anisotropy than graphene and TMDs [7], and recent theoretical studies show that the electronic properties of phosphorus nanoribbons depend on their edge states, which have different crystal lattice parameters [8,9].…”

“…The existing tailoring methods include a combination of electron beam lithography and plasma etching [10,11], chemical stripping [12], transmission electron microscopy [13], focused ion beams [4,14], catalytic cutting technique [15][16][17] and scanning laser lithography [18]. Although these tailoring methods are effective for various nanoscale materials, the fundamental restrictions of these methods reduce the applications of tailored ultra-thin films.…”