Search query: Two-dimensional semiconductors with possible high room temperature mobility

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abstract: We have calculated the longitudinal acoustic phonon limited electron mobility of 14 two dimensional semiconductors with composition of MX2, where M Mo, W, Sn, Hf, Zr and Pt) is the transition metal, and X is S, Se and Te. We treated the scattering matrix by the deformation potential approximation. We found that out of 14 compounds, MoTe2, HfSe2 and ZrSe2 are promising regarding to their possible high mobility and finite band gap. The phonon limited mobility can be above 2,500 cm2*V 1*s 1 at room temperature.
author_names: Wenxu Zhang

Zhishuo Huang

Wanli Zhang

Yanrong Li
title: Two dimensional semiconductors with possible high room temperature mobility
venue: Nano Research
year: 2014

abstract: We calculated the electron mobility of 14 two dimensional semiconductors with composition of MX2, where M Mo, W, Sn, Hf, Zr and Pt) is the transition metal, and X is S, Se and Te. We treated the scattering matrix by deformation potential approximation. Long wave longitudinal acoustical and optical phonon scatterings are included. Piezoelectric scattering in the compounds without inversion symmetry is also taken into account. We found that out of the 14 compounds, WSe2, PtS2 and PtSe2, are promising regarding to the possible high electron mobility and finite band gap. The phonon limited mobility in PtSe2 reaches about 3000 cm 2V 1s 1 at room temperature which is the highest among the compounds. The bandgap under the local density approximation is 1.25 eV. Our results can be a guide for experiments to search for better two dimensional materials for future semiconductor devices. a email to: xwzhang@uestc.edu.cn 1 ar X iv :1 50 5. 05 69 8v 1 co nd m at .m tr lsc i] 2 1 M ay 2 01 5
author_names: Zhishuo Huang

Wenxu Zhang

Wanli Zhang

Yanrong Li
title: Screening for Two dimensional MX$_2$ semiconductors with possible high room temperature mobility
year: 2015

abstract: Neither of the two typical two dimensional materials, graphene and single layer MoS2, are good enough for developing semiconductor logical devices. We calculated the electron mobility of 14 two dimensional semiconductors with composition of MX2, where M =Mo, W, Sn, Hf, Zr and Pt) are transition metals, and Xs are S, Se and Te. We approximated the electron phonon scattering matrix by deformation potentials, within which long wave longitudinal acoustical and optical phonon scatterings were included. Piezoelectric scattering in the compounds without inversion symmetry is also taken into account. We found that out of the 14 compounds, WS2, PtS2 and PtSe2 are promising for logical devices regarding the possible high electron mobility and finite band gap. Especially, the phonon limited electron mobility in PtSe2 reaches about 4000 cm2*V 1*s 1 at room temperature, which is the highest among the compounds with an indirect bandgap of about 1.25 eV under the local density approximation. Our results can be the first guide for experiments to synthesize better two dimensional materials for future semiconductor devices.
author_names: Zhishuo Huang

Wenxu Zhang

Wanli Zhang
title: Computational Search for Two Dimensional MX2 Semiconductors with Possible High Electron Mobility at Room Temperature
venue: Materials
year: 2016

abstract: A possible failure mechanism of n channel MOSFETs exposed to ionizing radiation are leakage currents between source and drain. This leakage begins to occur at relatively low radiation doses, and can seriously degrade the performance of an otherwise hardened CMOS device. In the present paper, we demonstrate by the observation of quantum oscillations in the magnetoresistance that by room temperature irradiation with high energy electrons an inversion layer is generated under the field oxide, which gives rise to leakage currents. Magnetoresistance oscillations may be observed, if in a degenerate electron gas the carrier mobility is sufficiently high to allow quantization of the electron movement in a magnetic field and the thermal energy is much smaller than the cyclotron energy. This oscillatory behaviour of the electrical resistance as a function of a magnetic field the Shubnikov de Haas effect is a valuable tool to investigate the electronic parameters of bulk semiconductors and surface channels. Such experiments not only give firm evidence about the existence of a bypass inversion layer, but also yield information about the carrier density in the radiation induced channel. It turns out that the electrons behave like a two dimensional free electron gas the density of which is independent of the gate voltage. Moreover, the experiments give knowledge about the influence of trapped charges, caused by the irradiation at the interface.
author_names: M Roos

Gottfried Landwehr
title: Shubnikov De Haas Oscillations Caused by a Two Dimensional Leakage Channel on Silicon Mosfets Induced by Electron Irradiation
venue: IEEE Transactions on Nuclear Science
year: 1978

abstract: Abstract Recently, Bi2O2Se is discovered as a promising two dimensional (2D) semiconductor for next generation electronics because of its stability in air, high Hall mobility and on/off ratio at room temperature. Using first principles calculations, we predict half metallicity in Mn doped monolayer Bi2O2Se. The magnetism enhancement from 4.0 to 6.0 uB and half metal to magnetic semiconductor transition of monolayer Bi2O2Se are realizable by applying biaxial tensile strain. The symmetry reduction at the elastic plastic transition is the key factor in controlling the magnetic coupling order between the Mn and the neighboring Se atoms. The results imply a possible way to achieve two dimensional magnetic semiconductors that have great potential applications in spintronic devices.
author_names: Y J Zhu

Xiaogang Wei

Yan Ming Song

Qi Wei

Changqing Lin

Nannan Han

Wenbo Mi

Yingchun Cheng

Wei Huang
title: Half metal to magnetic semiconductor transition in Mn doped monolayer Bi2O2Se tuned by strain
venue: Journal of Magnetism and Magnetic Materials
year: 2019

abstract: In this paper, we report high performance monolayer thin film transistors (TFTs) based on a variety of two dimensional layered semiconductors such as MoS2, WS2, and MoSe2 which were obtained from their corresponding bulk counterparts via an anomalous but high yield and low cost electrochemical corrosion process, also referred to as electro ablation (EA) at room temperature. These monolayer TFTs demonstrated current ON OFF ratios in excess of 107 along with ON currents of 120 mA/mm for MoS2, 40 mA/mm for WS2, and 40 mA/mm for MoSe2 which clearly outperform the existing TFT technologies. We found that these monolayers have larger Schottky barriers for electron injection compared to their multilayer counterparts, which is partially compensated by their superior electrostatics and ultra thin tunnel barriers. We observed an Anderson type semiconductor to metal transition in these monolayers and also discussed possible scattering mechanisms that manifest in the temperature dependence of the electron mobility. Finally, our study suggests superior chemical stability and electronic integrity of monolayers even after being exposed to extreme electro oxidation and corrosion processes which is promising for the implementation of such TFTs in harsh environment sensing. Overall, the EA process proves to be a facile synthesis route offering higher monolayer yields than mechanical exfoliation and lower cost and complexity than chemical vapor deposition methods.
author_names: Daniel S Schulman

Amritanand Sebastian

Drew Buzzell

Yu-ting Huang

Andrew J Arnold

Saptarshi Das
title: Facile Electrochemical Synthesis of 2D Monolayers for High Performance Thin Film Transistors.
venue: ACS applied materials interfaces
year: 2017

abstract: Two dimensional (2D) materials have attracted wide attention due to their exotic properties. In particular, the lack of dangling bonds makes it possible to build highly lattice mismatched heterostructures composed of 2D materials and conventional semiconductors. Here, we report that by simply stacking a chemical vapor deposition grown monolayer WS2 film onto the surface of a room temperature sputtered ZnO film, significant enhanced ultra violet (UV) photoresponse can be achieved. In this heterostructure of ZnO WS2, the ZnO film acts as a light harvesting layer while the WS2 monolayer functions as a carrier transport layer which facilitates the photocarrier transport and reduces its recombination. Such a mechanism was confirmed by the observation of further photoresponsivity improvement of the ZnO WS2 heterostructure under vacuum which removes the surface absorbates and thereby increases the carrier mobility of WS2. The strategy presented here can be applied to other wide band gap semiconductors, shedding light on high sensitivity and flexible UV photodetectors based on van der Waals heterostructures.
author_names: Changyong Lan

Chun Li

Shuaihao Wang

Yi Yin

Huayang Guo

Nishuang Liu

Yong Liu
title: ZnO WS2 heterostructures for enhanced ultra violet photodetectors
year: 2016

abstract: The recent discovery of graphene (Novoselov et al. 2004) a single atomic sheet of graphite, has ignited intense research activities to explore the electronic properties of this novel twodimensional (2D) electronic system. Charge transport in graphene differs from that in conventional 2D electronic systems as a consequence of the conical energy dispersion relation near the charge neutrality (Dirac) point in the electronic band structure (Zhang et al. 2005) Field effect mobility as high as 15 000 cm2/V.s and a Fermi velocity of ~108 cm/s have been demonstrated at room temperature (Geim Novoselov 2007) These properties make graphene a possible candidate for electronic devices in the future. The major benefit of graphene frequently quoted is superior electron/hole mobility compared to other semiconductors, but as Fig. 1 shows, this is not experimentally the case yet when compared to narrow bandgap III V semiconductors for comparable carrier densities. In addition, the lack of a bandgap limits the usage of two dimensional graphene for digital switching, where high on/off ratios are necessary. However, several potential advantages may be listed: the perfect 2D confinement of carriers, electron/hole symmetry originating from a conical bandstructure, and the possibility of opening bandgaps lithographically by fabricating graphene nanoribbons (GNRs) In Section 2, high field characteristics of 2D exfoliated graphene are reported on both short channel and longchannel back gated field effect transistors (FETs) We will elaborate on the problem of metal contact formation and high field transport of 2D graphene. The comparison of fabricated devices based on exfoliated, epitaxial and chemical vapour deposited (CVD) graphene will follow. The large area graphene opens the possibility to make 2D graphene devices for RF/analog amplification (Lin et al. 2010) Superior frequency performance of such devices makes it a promising application of 2D graphene FETs. The real advantage of graphene, however, can be highlighted from a novel proposed device architecture that is yet to be demonstrated (Zhang et al. 2008) If GNRs are made by lithographic patterning, and are either chemically or electrostatically doped into GNR p n junctions, then the planar form yields to a tunnelling field effect transistor (TFET) Towards the realization of the GNR TFET we designed a single but tuneable junction structure to demonstrate the operational principle. We discuss these GNR p n junction transistors in Section 3 along with the developed analytical and device models used to explain the measured transistor characteristics.
author_names: Kristof Tahy

Tian Fang

Pei Zhao

Aniruddha Konar

Chuanxin Lian

Michelle M Kelly

Debdeep Jena
title: 20 Graphene Transistors
year: 2012

abstract: To obtain room temperature ferromagnetic semiconductors is one of big challenges in science, and also premises essentially to realize room temperature quantum anomalous Hall effect (QAHE) both of which are quite expected for a long time. Here we report that, based on first principles calculations, PdBr3, PtBr3, PdI3 and PtI3 monolayers are ferromagnetic semiconductors with possible high temperature QAHE. Monte Carlo simulations give Curie temperatures 350 K and 375 K for PdBr3 and PtBr3 monolayers, respectively. These two dimensional (2D) materials are Chern insulators. The band gaps of PdBr3 and PtBr3 are 58.7 meV and 28.1 meV with GGA and 100.8 meV and 45 meV with HSE06, respectively, quite well in favor of observing room temperature QAHE. The large band gaps were unveiled from multi orbital electron correlations. By carefully checking the stability, PdBr3, PtBr3, and PtI3 monolayers are all predicted to be feasible in experiment. The present work sheds new light on developing promising spintronic devices by using the room temperature ferromagnetic semiconductors, and dissipationless devices by applying room temperature QAHE.
author_names: Jing-Yang You

Zhen Zhang

Bo Gu

Gang Su
title: Two Dimensional Room Temperature Ferromagnetic Semiconductors with Quantum Anomalous Hall Effect
venue: Physical Review Applied
year: 2019

abstract: Atomically thin (two dimensional, 2D) semiconductors have shown great potential as the fundamental building blocks for next generation electronics. However, all the 2D semiconductors that have been experimentally made so far have room temperature electron mobility lower than that of bulk silicon, which is not understood. Here, by using first principles calculations and reformulating the transport equations to isolate and quantify contributions of different mobility determining factors, we show that the universally low mobility of 2D semiconductors originates from the high "density of scatterings," which is intrinsic to the 2D material with a parabolic electron band. The density of scatterings characterizes the density of phonons that can interact with the electrons and can be fully determined from the electron and phonon band structures without knowledge of electron phonon coupling strength. Our work reveals the underlying physics limiting the electron mobility of 2D semiconductors and offers a descriptor to quickly assess the mobility.
author_names: Long Cheng

Chenmu Zhang

Yuanyue Liu
title: Why Two Dimensional Semiconductors Generally Have Low Electron Mobility.
venue: Physical review letters
year: 2020