Atomic Layer Deposition of a High-<i>k</i> Dielectric on MoS<sub>2</sub> Using Trimethylaluminum and Ozone

Cheng, Lanxia; Qin, Xiaoye; Lucero, Antonio T.; Azcatl, Angelica; Huang, Jie; Wallace, Robert M.; Cho, Kyeongjae; Kim, Jiyoung

doi:10.1021/am5032105

Cited by 111 publications

(131 citation statements)

References 31 publications

(74 reference statements)

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“…Thus, the top surface consists of the WS2 crystal basal planes and grain boundaries. It has been observed that the crystal basal planes of 2D materials typically have a low reactivity for ALD [36][37][38] . Instead, the chemisorption of ALD precursors on 2D materials can occur at line defects and grain boundaries 38 .…”

Section: A Substrate Enhanced Growth Of Ws2 Peald On Amorphous Al2o3mentioning

confidence: 99%

Nucleation mechanism during WS2 plasma enhanced atomic layer deposition on amorphous Al2O3 and sapphire substrates

Groven

Mehta

Bender

et al. 2017

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

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The structure, crystallinity and properties of as-deposited two-dimensional (2D) transition metal dichalcogenides are determined by nucleation mechanisms in the deposition process. 2D materials grown by atomic layer deposition (ALD) in absence of a template, are polycrystalline or amorphous. Little is known about their nucleation mechanisms.Therefore, we investigate the nucleation behavior of WS2 during plasma enhanced ALD from WF6, H2 plasma and H2S at 300 °C on amorphous ALD Al2O3 starting surface and on monocrystalline, bulk sapphire. Preferential interaction of the precursors with the Al2O3 starting surface promotes fast closure of the WS2 layer. The WS2 layers are fully continuous at WS2 content corresponding to only 1.2 WS2 monolayers. On amorphous Al2O3, (0002) textured and polycrystalline WS2 layers form with grain size of 5 nm to 20 nm due to high nucleation density (~10 14 nuclei/cm 2 ). The WS2 growth mode changes from 2D (layer-by-layer) growth on the initial Al2O3 surface to threedimensional (Volmer-Weber) growth after WS2 layer closure. Further growth proceeds from both WS2 basal planes in register with the underlying WS2 grain, and from or over grain boundaries of the underlying WS2 layer with different in-plane orientation. In contrast, on monocrystalline sapphire, WS2 crystal grains can locally align along a preferred in-plane orientation. Epitaxial seeding occurs locally albeit a large portion of crystals remain randomly oriented, presumably due to the low deposition temperature.The WS2 sheet resistance is 168 MΩµm suggesting that charge transport in the WS2 layers is limited by grain boundaries.3

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Section: A Substrate Enhanced Growth Of Ws2 Peald On Amorphous Al2o3mentioning

confidence: 99%

Nucleation mechanism during WS2 plasma enhanced atomic layer deposition on amorphous Al2O3 and sapphire substrates

Groven

Mehta

Bender

et al. 2017

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

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“…It inherits all the fundamental fabrication challenges of a TFET including doping profile, alignment especially gate registry, gate dielectrics, ohmic contacts. Atomic layer deposition has been improved over years to achieve good quality gate dielectrics on 2D crystals [32]. Using 2D dielectrics such as hexagonal boron nitride as the gate dielectrics has also been pursued [33].…”

Section: E Experimental Insightsmentioning

confidence: 99%

Two-Dimensional Heterojunction Interlayer Tunneling Field Effect Transistors (Thin-TFETs)

Esseni

Nahas

et al. 2015

IEEE J. Electron Devices Soc.

121

102

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Layered 2-D crystals embrace unique features of atomically thin bodies, dangling bond free\ud interfaces, and step-like 2-D density of states. To exploit these features for the design of a steep slope\ud transistor, we propose a Two-dimensional heterojunction interlayer tunneling field effect transistor (Thin-\ud TFET), where a steep subthreshold swing (SS) of ∼14 mV/dec and a high on-current of ∼300 μA/μm are\ud estimated theoretically. The SS is ultimately limited by the density of states broadening at the band edges\ud and the on-current density is estimated based on the interlayer charge transfer time measured in recent\ud experimental studies. To minimize supply voltage VDD while simultaneously maximizing on currents,\ud Thin-TFETs are best realized in heterostructures with near broken gap energy band alignment. Using\ud the WSe2/SnSe2 stacked-monolayer heterostructure, a model material system with desired properties for Thin-TFETs, the performance of both n-type and p-type Thin-TFETs is theoretically evaluated. Nonideal effects such as a nonuniform van der Waals gap thickness between the two 2-D semiconductors and finite total access resistance are also studied. Finally, we present a benchmark study for digital applications, showing the Thin-TFETs may outperform CMOS and III–V TFETs in term of both switching speed and energy consumption at low-supply voltages

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“…Each MoS 2 TFT channel was defined by photolithography and dry-etching (O 2 plasma treatment) isolation process [the detailed APCVD process flow and material properties of the transferred and isolated MoS 2 thin film are shown in Figure S1 (Supporting Information), which includes the Raman spectra and atomic force microscopy (AFM) profile]. [30,[45][46][47] During the fabrication process, via holes through the Al 2 O 3 GI layer, defined by photolithography and wet-etching process using buffered oxide etchant (BOE), were formed to connect the source electrode of the switching TFT and gate electrode of the driving TFT. [30] For the source/drain electrode, Ti/Au was employed for ohmic contact to the MoS 2 active layer.…”

mentioning

confidence: 99%

Large‐Area CVD‐Grown MoS₂ Driver Circuit Array for Flexible Organic Light‐Emitting Diode Display

Woo

Wang

Yang

et al. 2018

Adv Elect Materials

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2D‐layered transition metal dichalcogenides (TMDCs) such as molybdenum disulfide (MoS2) are promising materials for next‐generation active matrix organic light‐emitting diode (AMOLED) display technology owing to their high mobility and large bandgap size. However, practical applications of TMDCs in driving circuits for flexible displays remain challenging because of the lack of high‐quality large‐area thin films and suitable fabrication processes. Here, millimeter‐scale large‐area bilayer or trilayer MoS2 thin films are synthesized through chemical vapor deposition (CVD) and an AMOLED driver circuit array consisting of bottom‐gate staggered CVD‐grown MoS2 thin‐film transistors is fabricated on a flexible polyimide substrate. The flexible driver circuit exhibits a stable switching and driving operation under tensile strain induced by a bending radius of 3.5 mm, showing field‐effect mobilities of up to ≈9 cm2 V−1 s−1, large ON‐state current density (up to ≈5 µA µm−1), and high ON/OFF‐state drain current ratio (maximum value of over 108) with an operating gate voltage below 10 V. The results demonstrate that MoS2 backplanes are among the promising candidates for next‐generation deformable and transparent AMOLED displays.

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Atomic Layer Deposition of a High-k Dielectric on MoS₂ Using Trimethylaluminum and Ozone

Cited by 111 publications

References 31 publications

Nucleation mechanism during WS2 plasma enhanced atomic layer deposition on amorphous Al2O3 and sapphire substrates

Nucleation mechanism during WS2 plasma enhanced atomic layer deposition on amorphous Al2O3 and sapphire substrates

Two-Dimensional Heterojunction Interlayer Tunneling Field Effect Transistors (Thin-TFETs)

Large‐Area CVD‐Grown MoS₂ Driver Circuit Array for Flexible Organic Light‐Emitting Diode Display

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Atomic Layer Deposition of a High-k Dielectric on MoS2 Using Trimethylaluminum and Ozone

Cited by 111 publications

References 31 publications

Nucleation mechanism during WS2 plasma enhanced atomic layer deposition on amorphous Al2O3 and sapphire substrates

Nucleation mechanism during WS2 plasma enhanced atomic layer deposition on amorphous Al2O3 and sapphire substrates

Two-Dimensional Heterojunction Interlayer Tunneling Field Effect Transistors (Thin-TFETs)

Large‐Area CVD‐Grown MoS2 Driver Circuit Array for Flexible Organic Light‐Emitting Diode Display

Contact Info

Product

Resources

About

Atomic Layer Deposition of a High-k Dielectric on MoS₂ Using Trimethylaluminum and Ozone

Large‐Area CVD‐Grown MoS₂ Driver Circuit Array for Flexible Organic Light‐Emitting Diode Display