Query: Few-layer MoS2: a promising layered semiconductor

Candidate papers:

abstract: Due to the recent expanding interest in two dimensional layered materials, molybdenum disulfide (MoS2) has been receiving much research attention. Having an ultrathin layered structure and an appreciable direct band gap of 1.9 eV in the monolayer regime, few layer MoS2 has good potential applications in nanoelectronics, optoelectronics, and flexible devices. In addition, the capability of controlling spin and valley degrees of freedom makes it a promising material for spintronic and valleytronic devices. In this review, we attempt to provide an overview of the research relevant to the structural and physical properties, fabrication methods, and electronic devices of few layer MoS2. Recent developments and advances in studying the material are highlighted.
author_names: Rudren Ganatra

Qing Yu Zhang
title: Few layer MoS2: a promising layered semiconductor.
venue: ACS nano
year: 2014

abstract: Two dimensional materials are attractive for use in next generation nanoelectronic devices because, compared to one dimensional materials, it is relatively easy to fabricate complex structures from them. The most widely studied two dimensional material is graphene, both because of its rich physics and its high mobility. However, pristine graphene does not have a bandgap, a property that is essential for many applications, including transistors. Engineering a graphene bandgap increases fabrication complexity and either reduces mobilities to the level of strained silicon films or requires high voltages. Although single layers of MoS(2) have a large intrinsic bandgap of 1.8 eV (ref. 16) previously reported mobilities in the 0.5 3 cm(2) V( 1) s( 1) range are too low for practical devices. Here, we use a halfnium oxide gate dielectric to demonstrate a room temperature single layer MoS(2) mobility of at least 200 cm(2) V( 1) s( 1) similar to that of graphene nanoribbons, and demonstrate transistors with room temperature current on/off ratios of 1 x 10(8) and ultralow standby power dissipation. Because monolayer MoS(2) has a direct bandgap, it can be used to construct interband tunnel FETs, which offer lower power consumption than classical transistors. Monolayer MoS(2) could also complement graphene in applications that require thin transparent semiconductors, such as optoelectronics and energy harvesting.
author_names: Branimir Radisavljevic

Aleksandra Radenovic

Jacopo Brivio

Valentina Giacometti

Andras Kis
title: Single layer MoS2 transistors.
venue: Nature nanotechnology
year: 2011

abstract: Molybdenum disulfide (MoS(2) of single and few layer thickness was exfoliated on SiO(2)/Si substrate and characterized by Raman spectroscopy. The number of S Mo S layers of the samples was independently determined by contact mode atomic force microscopy. Two Raman modes, E(1)(2g) and A(1g) exhibited sensitive thickness dependence, with the frequency of the former decreasing and that of the latter increasing with thickness. The results provide a convenient and reliable means for determining layer thickness with atomic level precision. The opposite direction of the frequency shifts, which cannot be explained solely by van der Waals interlayer coupling, is attributed to Coulombic interactions and possible stacking induced changes of the intralayer bonding. This work exemplifies the evolution of structural parameters in layered materials in changing from the three dimensional to the two dimensional regime.
author_names: Changgu Lee

Hugen Yan

Louis E Brus

Tony F Heinz

James C Hone

Sunmin Ryu
title: Anomalous lattice vibrations of single and few layer MoS2.
venue: ACS nano
year: 2010

abstract: A new phototransistor based on the mechanically exfoliated single layer MoS(2) nanosheet is fabricated, and its light induced electric properties are investigated in detail. Photocurrent generated from the phototransistor is solely determined by the illuminated optical power at a constant drain or gate voltage. The switching behavior of photocurrent generation and annihilation can be completely finished within ca. 50 ms, and it shows good stability. Especially, the single layer MoS(2) phototransistor exhibits a better photoresponsivity as compared with the graphene based device. The unique characteristics of incident light control, prompt photoswitching, and good photoresponsivity from the MoS(2) phototransistor pave an avenue to develop the single layer semiconducting materials for multifunctional optoelectronic device applications in the future.
author_names: Zongyou Yin

Hai Li

Hong Li

Lin Jiang

Yumeng Shi

Yinghui Sun

Gang Lu

Qing Yu Zhang

Xiaodong Chen

Hua Zhang
title: Single layer MoS2 phototransistors.
venue: ACS nano
year: 2012

abstract: Large area MoS(2) atomic layers are synthesized on SiO(2) substrates by chemical vapor deposition using MoO(3) and S powders as the reactants. Optical, microscopic and electrical measurements suggest that the synthetic process leads to the growth of MoS(2) monolayer. The TEM images verify that the synthesized MoS(2) sheets are highly crystalline.
author_names: Yi-Hsien Lee

Xin-Quan Zhang

Wenjing Zhang

M T Chang

Cheng-Te Lin

Kai Chang

Ya-Chu Yu

Jacob Tse-Wei Wang

Chia-Seng Chang

Lain-Jong Li

Tsung-Wu Lin
title: Synthesis of large area MoS2 atomic layers with chemical vapor deposition.
venue: Advanced materials
year: 2012

abstract: In this work we present a low cost and scalable technique, via ambient pressure chemical vapor deposition (CVD) on polycrystalline Ni films, to fabricate large area approximately cm2) films of single to few layer graphene and to transfer the films to nonspecific substrates. These films consist of regions of 1 to approximately 12 graphene layers. Single or bilayer regions can be up to 20 mum in lateral size. The films are continuous over the entire area and can be patterned lithographically or by prepatterning the underlying Ni film. The transparency, conductivity, and ambipolar transfer characteristics of the films suggest their potential as another materials candidate for electronics and opto electronic applications.
author_names: Alfonso Reina

Xiaoting Jia

John T Ho

Daniel Nezich

Hyungbin Son

Vladimir Bulovic

Mildred S Dresselhaus

Jing Kong
title: Large area, few layer graphene films on arbitrary substrates by chemical vapor deposition.
venue: Nano letters
year: 2009

abstract: A two dimensional crystal of molybdenum disulfide (MoS2) monolayer is a photoluminescent direct gap semiconductor in striking contrast to its bulk counterpart. Exfoliation of bulk MoS2 via Li intercalation is an attractive route to large scale synthesis of monolayer crystals. However, this method results in loss of pristine semiconducting properties of MoS2 due to structural changes that occur during Li intercalation. Here, we report structural and electronic properties of chemically exfoliated MoS2. The metastable metallic phase that emerges from Li intercalation was found to dominate the properties of as exfoliated material, but mild annealing leads to gradual restoration of the semiconducting phase. Above an annealing temperature of 300 degC, chemically exfoliated MoS2 exhibit prominent band gap photoluminescence, similar to mechanically exfoliated monolayers, indicating that their semiconducting properties are largely restored.
author_names: Goki Eda

Hisato Yamaguchi

Damien Voiry

Takeshi Fujita

Mingwei Chen

Manish Chhowalla
title: Photoluminescence from chemically exfoliated MoS2.
venue: Nano letters
year: 2011

abstract: Logic circuits and the ability to amplify electrical signals form the functional backbone of electronics along with the possibility to integrate multiple elements on the same chip. The miniaturization of electronic circuits is expected to reach fundamental limits in the near future. Two dimensional materials such as single layer MoS(2) represent the ultimate limit of miniaturization in the vertical dimension, are interesting as building blocks of low power nanoelectronic devices, and are suitable for integration due to their planar geometry. Because they are less than 1 nm thin, 2D materials in transistors could also lead to reduced short channel effects and result in fabrication of smaller and more power efficient transistors. Here, we report on the first integrated circuit based on a two dimensional semiconductor MoS(2) Our integrated circuits are capable of operating as inverters, converting logical "1" into logical "0" with room temperature voltage gain higher than 1, making them suitable for incorporation into digital circuits. We also show that electrical circuits composed of single layer MoS(2) transistors are capable of performing the NOR logic operation, the basis from which all logical operations and full digital functionality can be deduced.
author_names: Branimir Radisavljevic

Michael Brian Whitwick

Andras Kis
title: Integrated circuits and logic operations based on single layer MoS2.
venue: ACS nano
year: 2011

abstract: Layered compounds such as MoS2, WS2, MoSe2, TaSe2, NbSe2, NiTe2, BN, and Bi2Te3 are exfoliated by sonication of powders of the materials in a number of solvents with varying surface tensions and deposited as individual flakes or formed into films.
author_names: Jonathan N Coleman
title: Two Dimensional Nanosheets Produced by Liquid Exfoliation of Layered Materials.
year: 2011

abstract: Based on first principles plane wave calculations, we studied the functionalization of the two dimensional single layer MoS2 structure through adatom adsorption and vacancy defect creation. Minimum energy adsorption sites were determined for 16 different adatoms, each of which gives rise to diverse properties. Bare, single layer MoS2, which is normally a nonmagnetic, direct band gap semiconductor, attains a net magnetic moment upon adsorption of specific transition metal atoms, as well as silicon and germanium atoms. The localized donor and acceptor states in the band gap expand the utilization of MoS2 in nanoelectronics and spintronics. Specific adatoms, such as C and O, attain significant excess charge upon adsorption onto single layer MoS2, which might be useful for tribological applications. Each MoS2 triple vacancy created in a single layer of MoS2 gives rise to a net magnetic moment, whereas other vacancy defects related to Mo and S atoms do not influence the nonmagnetic ground state. The present re.
author_names: Can Ataca

Salim Ciraci
title: Functionalization of Single Layer MoS2 Honeycomb Structures
year: 2010