Search query: Single Layer MoS2 Transistors

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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: 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: 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: Ubiquitous low frequency 1/f noise can be a limiting factor in the performance and application of nanoscale devices. Here, we quantitatively investigate low frequency electronic noise in single layer transition metal dichalcogenide MoS2 field effect transistors. The measured 1/f noise can be explained by an empirical formulation of mobility fluctuations with the Hooge parameter ranging between 0.005 and 2.0 in vacuum <10( 5) Torr) The field effect mobility decreased, and the noise amplitude increased by an order of magnitude in ambient conditions, revealing the significant influence of atmospheric adsorbates on charge transport. In addition, single Lorentzian generation recombination noise was observed to increase by an order of magnitude as the devices were cooled from 300 to 6.5 K.
author_names: Vinod K Sangwan

Heather N Arnold

Deep Jariwala

Tobin J Marks

Lincoln J Lauhon

Mark C Hersam
title: Low frequency electronic noise in single layer MoS2 transistors.
venue: Nano letters
year: 2013

abstract: While there has been growing interest in two dimensional (2 D) crystals other than graphene, evaluating their potential usefulness for electronic applications is still in its infancy due to the lack of a complete picture of their performance potential. The focus of this article is on contacts. We demonstrate that through a proper understanding and design of source/drain contacts and the right choice of number of MoS(2) layers the excellent intrinsic properties of this 2 D material can be harvested. Using scandium contacts on 10 nm thick exfoliated MoS(2) flakes that are covered by a 15 nm Al(2)O(3) film, high effective mobilities of 700 cm(2)(V s) are achieved at room temperature. This breakthrough is largely attributed to the fact that we succeeded in eliminating contact resistance effects that limited the device performance in the past unrecognized. In fact, the apparent linear dependence of current on drain voltage had mislead researchers to believe that a truly Ohmic contact had already been achieved, a misconception that we also elucidate in the present article.
author_names: Saptarshi Das

Hong-Yan Chen

Ashish Verma Penumatcha

Joerg Appenzeller
title: High performance multilayer MoS2 transistors with scandium contacts.
venue: Nano letters
year: 2013

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: Abstract MoS 2 has been exfoliated into monolayers by intercalation with lithium followed by reaction with water. X ray diffraction analysis has shown that the exfoliated MoS 2 in suspension is in the form of one molecule thick sheets. X ray patterns from dried and re stacked films of exfoliated MoS 2 indicate that the layers are randomly stacked. Exfoliated MoS 2 has been deposited on alumina particles in aqueous suspension, enabling recovery of dry exfoliated MoS 2 supported on alumina.
author_names: Per Joensen

R F Frindt

Stanley Roy Morrison
title: Single layer MoS2
year: 1986

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

abstract: We have studied using scanning tunneling microscopy (STM) the atomic scale realm of molybdenum disulfide MoS2) nanoclusters, which are of interest as a model system in hydrodesulfurization catalysis. The STM gives the first real space images of the shape and edge structure of single layer MoS2 nanoparticles synthesized on Au(111) and establishes a new picture of the active edge sites of the nanoclusters. The results demonstrate a way to get detailed atomic scale information on catalysts in general.
title: Atomic scale structure of single layer MoS2 nanoclusters
venue: Physical review letters
year: 2000

abstract: Two dimensional materials are an emerging class of new materials with a wide range of electrical properties and potential practical applications. Although graphene is the most well studied two dimensional material, single layers of other materials, such as insulating BN (ref. 2) and semiconducting MoS2 (refs 3, 4) or WSe2 (refs 5, 6) are gaining increasing attention as promising gate insulators and channel materials for field effect transistors. Because monolayer MoS2 is a direct bandgap semiconductor due to quantum mechanical confinement, it could be suitable for applications in optoelectronic devices where the direct bandgap would allow a high absorption coefficient and efficient electron hole pair generation under photoexcitation. Here, we demonstrate ultrasensitive monolayer MoS2 phototransistors with improved device mobility and ON current. Our devices show a maximum external photoresponsivity of 880 A W( 1) at a wavelength of 561 nm and a photoresponse in the 400 680 nm range. With recent developments in large scale production techniques such as liquid scale exfoliation and chemical vapour deposition like growth, MoS2 shows important potential for applications in MoS2 based integrated optoelectronic circuits, light sensing, biomedical imaging, video recording and spectroscopy.
author_names: Oriol Lopez-Sanchez

Dominik S Lembke

M Kayci

Aleksandra Radenovic

Andras Kis
title: Ultrasensitive photodetectors based on monolayer MoS2.
venue: Nature nanotechnology
year: 2013