Humidity‐Controlled Ultralow Power Layer‐by‐Layer Thinning, Nanopatterning and Bandgap Engineering of MoTe<sub>2</sub>

Nagareddy, V. Karthik; Octon, T; Townsend, Nicola J.; Russo, Saverio; Craciun, Monica F.; Wright, C. David

doi:10.1002/adfm.201804434

Cited by 31 publications

(43 citation statements)

References 46 publications

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“…Because we regard the interlayer as MoO x which has a large work function so as to deplete electron charges in both p‐MoTe 2 and n‐Ga 2 O 3 , the final band structure of the heterojunction is described as the form in Figure 2e. [ 28–30 ] Here, we use the built‐in potential energy (qV b or qφ i = 0.65 eV), energy gap of MoTe 2 (=1.0 eV), [ 31,32 ] and energy gap of β‐Ga 2 O 3 (=4.8 eV). [ 33,34 ]…”

Section: Resultsmentioning

confidence: 99%

Ambipolar Channel p‐TMD/n‐Ga₂O₃ Junction Field Effect Transistors and High Speed Photo‐sensing in TMD Channel

et al. 2021

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Highly crystalline 2D/3D‐mixed p‐transition metal dichalcogenide (TMD)/n‐Ga2O3 heterojunction devices are fabricated by mechanical exfoliation of each p‐ and n‐type material. N‐type β‐Ga2O3 and p‐type TMD separately play as a channel for junction field effect transistors (JFETs) with each type of carriers as well as materials for a heterojunction PN diode. The work thus mainly focuses on such ambipolar channel transistors with two different types of channel in a single device architecture. For more extended applications, the transparency of high energy band gap β‐Ga2O3 (Eg ≈ 4.8 eV) is taken advantage of, firstly to measure the electrical energy gap of p‐TMDs receiving visible or near infrared (NIR) photons through the β‐Ga2O3. Next, the p‐TMD/n‐Ga2O3 JFETs are put to high speed photo‐sensing which is achieved from the p‐TMD channel under reverse bias voltages on n‐Ga2O3. The photo‐switching cutoff frequency appears to be ≈16 and 29 kHz for visible red and NIR illuminations, respectively, on the basis of −3 dB photoelectric power loss. Such a high switching speed of the JFET is attributed to the fast transport of photo‐carriers in TMD channels. The 2D/3D‐mixed ambipolar channel JFETs and their photo‐sensing applications are regarded novel, promising, and practically easy to achieve.

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Section: Resultsmentioning

confidence: 99%

Ambipolar Channel p‐TMD/n‐Ga₂O₃ Junction Field Effect Transistors and High Speed Photo‐sensing in TMD Channel

et al. 2021

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“…Optical modification methods have been widely used to improve the direct synthesis of large‐area 2D materials. Among these methods, we focus on laser‐assisted CVD (LCVD), [ 14,45–54 ] optical synthesis of TMDs, [ 55 ] laser‐assisted liquid phase exfoliation (LPE), [ 56,57 ] laser‐induced graphene synthesis, [ 58,59 ] and highly controllable laser ablation and thinning [ 24–28,60–64 ] of a bulk material down to a monolayer. As all of these methods use lasers as the light sources, the processes are easily tuned with laser parameters, such as power, [ 50–52,65 ] fluence, [ 65 ] wavelength, [ 47,50–54 ] scanning speed, [ 49,50,52 ] illumination time, [ 51,54 ] and thermal cycle time.…”

Section: Laser‐based Synthesis and Fabricationmentioning

confidence: 99%

Optical Modification of 2D Materials: Methods and Applications

2022

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on the same chip, which is promising for integrated electronics or photonics applications, [7] such as lasers, [8][9][10] optical modulators, [11] and photodetectors. [12] Indeed, 2D materials are an excellent candidate for postsilicone electronics due to their unique properties, versatile scaling of channel length, reduced device dimensionalities, and the possibility of creating circuits nearly at the atomic level. [13] Currently, some of the biggest challenges for 2D material synthesis include the lack of large-scale manufacturing and the necessity of harsh or arduous microand nanofabrication methods. Typical fabrication methods are based on chemical vapor deposition (CVD) and mechanical exfoliation from bulk crystals. The former involves a process that results in layers with relatively high concentrations of atomic impurities, [14] and the latter is limited in producing large area flakes. [14] Further fabrication steps for the incorporation of 2D materials into integrated devices typically require processes like electron-beam lithography and reactive ion etching, [15] both of which can be harmful to flakes that are atomically thin.All-optical processing of 2D materials has been demonstrated to overcome limitations of the conventional synthesis methods. It is time-and cost-effective, and it is also a promising fabrication alternative over CVD and mechanical exfoliation. Optical modification processes offer selectivity, locality, directionality, tunability, less harmful conditions, and on-demand functionalities, such as optical doping, [16][17][18][19] oxidation, [20][21][22][23] optical thinning, [24][25][26][27][28] and phase change. [29][30][31][32] Additionally, almost all of the optical modification and fabrication methods can be used for laser-direct writing (LDW) of patterns and structures at the microscale. [33][34][35][36] The high precision of LDW is particularly advantageous in the evolving world of nanofabrication. Lasers allow local modification of 2D material electronic bandgap, [37] thickness, [25] strain, [33,[38][39][40] and chemical composition, [19,41,42] even beyond the diffraction limit. [33] The created structures and patterns can often be directly used for applications in sensors, [22] energyprocessing devices, [43] and holography [44] (Figure 1). All the major demonstrations using LDW on 2D materials are listed in Table 1. Here, we review the optically assisted synthesis and fabrication methods of 2D materials, and their state-of-theart applications, providing detailed descriptions and features of optically engineered devices using 2D materials. We have straightforwardly introduced light-matter interactions and 2D-material-light interactions, and we also present our perspectives on this emerging field.2D materials are under extensive research due to their remarkable properties suitable for various optoelectronic, photonic, and biological applications, yet their conventional fabrication methods are typically harsh and costineffective. Optical modification is demonstrated as an effective an...

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Section: Laser Thinning Through Sublimationmentioning

confidence: 99%

“…With a directbandgap energy of 1.13 eV [9] similar to that of silicon, which extends the spectral response to the near-infrared (NIR) region, MoTe 2 is favorable for devices such as tunnel field-effect transistors (FETs) and NIR detectors. Recently, Nagareddy et al have proposed a humidity-controlled laser thinning technique where layer-by-layer laser thinning of MoTe 2 was achieved for the sample that was maintained at a relative humidity of more than 65-70% [48]. Laser powers much lower than those used for laser thinning through oxidation or sublimation were used because the low bond energies of MoTe 2 result in an uncontrolled bond-breaking at relatively higher laser powers.…”

Section: Laser Thinning Through Sublimationmentioning

confidence: 99%

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Optical Patterning of Two-Dimensional Materials

Kollipara

Zheng

2020

Research

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Recent advances in the field of two-dimensional (2D) materials have led to new electronic and photonic devices enabled by their unique properties at atomic thickness. Structuring 2D materials into desired patterns on substrates is often an essential and foremost step for the optimum performance of the functional devices. In this regard, optical patterning of 2D materials has received enormous interest due to its advantages of high-throughput, site-specific, and on-demand fabrication. Recent years have witnessed scientific reports of a variety of optical techniques applicable to patterning 2D materials. In this minireview, we present the state-of-the-art optical patterning of 2D materials, including laser thinning, doping, phase transition, oxidation, and ablation. Several applications based on optically patterned 2D materials will be discussed as well. With further developments, optical patterning is expected to hold the key in pushing the frontiers of manufacturing and applications of 2D materials.

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Humidity‐Controlled Ultralow Power Layer‐by‐Layer Thinning, Nanopatterning and Bandgap Engineering of MoTe₂

Cited by 31 publications

References 46 publications

Ambipolar Channel p‐TMD/n‐Ga₂O₃ Junction Field Effect Transistors and High Speed Photo‐sensing in TMD Channel

Ambipolar Channel p‐TMD/n‐Ga₂O₃ Junction Field Effect Transistors and High Speed Photo‐sensing in TMD Channel

Optical Modification of 2D Materials: Methods and Applications

Optical Patterning of Two-Dimensional Materials

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Humidity‐Controlled Ultralow Power Layer‐by‐Layer Thinning, Nanopatterning and Bandgap Engineering of MoTe2

Cited by 31 publications

References 46 publications

Ambipolar Channel p‐TMD/n‐Ga2O3 Junction Field Effect Transistors and High Speed Photo‐sensing in TMD Channel

Ambipolar Channel p‐TMD/n‐Ga2O3 Junction Field Effect Transistors and High Speed Photo‐sensing in TMD Channel

Optical Modification of 2D Materials: Methods and Applications

Optical Patterning of Two-Dimensional Materials

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Humidity‐Controlled Ultralow Power Layer‐by‐Layer Thinning, Nanopatterning and Bandgap Engineering of MoTe₂

Ambipolar Channel p‐TMD/n‐Ga₂O₃ Junction Field Effect Transistors and High Speed Photo‐sensing in TMD Channel

Ambipolar Channel p‐TMD/n‐Ga₂O₃ Junction Field Effect Transistors and High Speed Photo‐sensing in TMD Channel