Strong electrically tunable MoTe2/graphene van der Waals heterostructures for high-performance electronic and optoelectronic devices
MoTe2 is an emerging two-dimensional layeredmaterial showing ambipolar/p-type conductivity, which makes it an important supplement to n-type two-dimensional layeredmaterial like MoS2. However, theproperties based on its van der Waals heterostructures have been rarely studied. Here, taking advantage of the strongFermi level tunability ofmonolayergraphene (G) and the feature of van der Waals interfaces that is free fromFermi level pinning effect, wefabricate G/MoTe2/G van der Waals heterostructures and systematically study the electronic and optoelectronicproperties. We demonstrate the G/MoTe2/GFETs with low Schottky barrier...
Source: Applied Physics Letters - November 8, 2016 Category: Physics Authors: Feng Wang, Lei Yin, Zhenxing Wang, Kai Xu, Fengmei Wang, Tofik Ahmed Shifa, Yun Huang, Yao Wen, Chao Jiang and Jun He Source Type: research
High-performance rectifiers fabricated on a flexible substrate
We report on the fabrication andtesting of metal-insulator-metal (MIM) diodes on a flexible substrate where the thin insulating layer self-assembles as a monolayer sandwiched between the two metal electrodes. The current-voltage characteristic has a strong asymmetry and non-linearity at zero-bias. The diodes have a typical zero-biasresistance of 80 kΩ, a zero-bias curvature coefficient of 5.5 V−1, and a voltage responsivity of 3.1 kV/W at a frequency of 1 GHz. The fabrication yield was over 90%, and an encapsulation method to prevent MIM junction degradation has also been developed. The diodes show no significan...
Source: Applied Physics Letters - November 8, 2016 Category: Physics Authors: David Etor, Linzi E. Dodd, David Wood and Claudio Balocco Source Type: research
Photothermal characterization of MoS2 emission coupled to a microdisk cavity
Integration of emerging two-dimensional direct bandgap semiconductors ontooptical microcavities is important for nanophotonic light sources. In most cases, to achieve high quality factors, suchmicrocavity designs require thermally isolated structures leading to pronouncedphotothermal effects. Here, we report experimental results on spectroscopic and time-domain characterization ofphotothermal response from MoS2monolayers coupled to microdiskresonators. We find that judicious utilization of pulsed laser excitation can circumvent irreversible photoabsorption inducedmaterial damage. Our results agree well with finite element ...
Source: Applied Physics Letters - November 8, 2016 Category: Physics Authors: Jason C Reed, Stephanie C. Malek, Fei Yi, Carl H. Naylor, A. T. Charlie Johnson and Ertugrul Cubukcu Source Type: research
Exciton spin relaxation in InAs/InGaAlAs/InP(001) quantum dashes emitting near 1.55 μm
Exciton spin and related opticalpolarization inself-assembled InAs/In0.53Ga0.23Al0.24As/InP(001) quantum dashes emitting at 1.55 μm are investigated by means of polarization- and time-resolvedphotoluminescence, as well asphotoluminescence excitation spectroscopy, at cryogenic temperature. We investigate the influence of highly non-resonant and quasi-resonant optical spin pumping conditions on spinpolarization and spin memory of the quantum dashground state. We show that a spin pumping scheme, utilizing the longitudinal-optical-phonon-mediated coherent scattering process, can lead to thepolarization degree above 50%. We...
Source: Applied Physics Letters - November 8, 2016 Category: Physics Authors: M. Syperek, Ł. Dusanowski, M. Gawełczyk, G. Sȩk, A. Somers, J. P. Reithmaier, S. Höfling and J. Misiewicz Source Type: research
Particle size selection in post-spark dusty plasma in non-uniform electric field
We report a strong size-selective effect of the non-uniform externalelectric field on unitary chargednanoparticles in a residualdusty plasma generated bysparkdischarge. It has been found that the field influences the outcome particle size distribution function considerably by expelling smaller particles out of the residualplasma cloud so that they cannot neutralize or agglomerate. Meantime, larger particles being dragged by theplasma cloud neutralize and disappear at walls; therefore, the particle size distribution function shifts to small sizes. We give a simple theory explaining the field effect and suggest its applicati...
Source: Applied Physics Letters - November 8, 2016 Category: Physics Authors: Woongsik Kim, Peter V. Pikhitsa and Mansoo Choi Source Type: research
Role of film stoichiometry and interface quality in the performance of (Ba,Sr)TiO3 tunable capacitors with high figures of merit
Parallel platecapacitors with quality factors exceeding 1000 were fabricated using Ba0.3Sr0.7TiO3 (BST) thinfilms grown by hybridmolecular beam epitaxy on epitaxial Pt bottomelectrodes. The influence offilmstoichiometry was investigated by varying the (Ba + Sr)/Ti ratio around thestoichiometric composition. The quality factor is highest forstoichiometricfilms, but (Ba + Sr)-richfilms can be biased to higher fields. Furthermore, two different processes were used todeposit the topelectrodes of the parallel platecapacitors. While the quality of the top contact/BST interface did not strongly affect thedevice quality factor, an...
Source: Applied Physics Letters - November 8, 2016 Category: Physics Authors: Christopher R. Freeze and Susanne Stemmer Source Type: research
Response to “Comment on ‘Catastrophic degradation of the interface of epitaxial silicon carbide on silicon at high temperatures’” [Appl. Phys. Lett. 109, 196101 (2016)]
(Source: Applied Physics Letters)
Source: Applied Physics Letters - November 8, 2016 Category: Physics Authors: Aiswarya Pradeepkumar, Neeraj Mishra, Atieh Ranjbar Kermany, John J. Boeckl, Jack Hellerstedt, Michael S. Fuhrer and Francesca Iacopi Source Type: research
Comment on “Catastrophic degradation of the interface of epitaxial silicon carbide on silicon at high temperatures” [Appl. Phys. Lett. 109, 011604 (2016)]
(Source: Applied Physics Letters)
Source: Applied Physics Letters - November 8, 2016 Category: Physics Authors: Sima Dimitrijev Source Type: research
Fully ALD-grown TiN/Hf0.5Zr0.5O2/TiN stacks: Ferroelectric and structural properties
Since the discovery of ferroelectricity (FE) in HfO2-basedthin films, they are gaining increasing attention as a viable alternative to conventional FE in the next generation of non-volatile memory devices. In order to further increase the density of elements in the integrated circuits, it is essential to adopt a three-dimensional design. Sinceatomic layer deposition(ALD) processes are extremely conformal,ALD is the favored approach in the production of 3Dferroelectric random access memory. Here, we report the fabrication of fully ALD-growncapacitors comprising a 10-nm-thick FE Hf0.5Zr0.5O2 layer sandwiched between TiNelect...
Source: Applied Physics Letters - November 8, 2016 Category: Physics Authors: Sergei Zarubin, Elena Suvorova, Maksim Spiridonov, Dmitrii Negrov, Anna Chernikova, Andrey Markeev and Andrei Zenkevich Source Type: research
Probing the exciton-phonon coupling strengths of O-polar and Zn-polar ZnO wafer using hard X-ray excited optical luminescence
Thetemperature-dependent hardX-ray excited optical luminescence (XEOL) spectroscopy was used to study theoptical properties of O andZn polarity of a c-plane single crystalZnO wafer. By analyzing the XEOL andXRD, we found an unprecedentedblue shift of the freeexciton transition with increasing the excited carrier density as tuning theX-ray energy across theZn K-edge, and the O-polar face possesses better crystal structure than the Zn-polar one. This spectralblue shift is attributed to the Coulomb screening of the spontaneous polarization by the excited free carriers that result in decreasing the exciton-phonon Fr öhlich in...
Source: Applied Physics Letters - November 8, 2016 Category: Physics Authors: Bi-Hsuan Lin, Huang-Yeh Chen, Shao-Chin Tseng, Jian-Xing Wu, Bo-Yi Chen, Chien-Yu Lee, Gung-Chian Yin, Shih-Hung Chang, Mau-Tsu Tang and Wen-Feng Hsieh Source Type: research
Imaging and manipulation of skyrmion lattice domains in Cu2OSeO3
Nanoscalechiralskyrmions in noncentrosymmetric helimagnets are promising binary state variables in high-density, low-energy nonvolatile memory.Skyrmions are ubiquitous as an ordered, single-domain lattice phase, which makes it difficult to write information unless they are spatially broken up into smaller units, each representing a bit. Thus, the formation and manipulation ofskyrmion lattice domains is a prerequisite for memory applications. Here, using an imaging technique based on resonant magneticx-ray diffraction, we demonstrate the mapping and manipulation ofskyrmion lattice domains in Cu2OSeO3. Thematerial is particu...
Source: Applied Physics Letters - November 8, 2016 Category: Physics Authors: S. L. Zhang, A. Bauer, H. Berger, C. Pfleiderer, G. van der Laan and T. Hesjedal Source Type: research
Critical role of W deposition condition on spin-orbit torque induced magnetization switching in nanoscale W/CoFeB/MgO
We study the spin-orbittorque induced magnetization switching in W/CoFeB/MgO heterostructures with Wdeposited under differentsputtering conditions. We show that the crystal structure andresistivity of W depend on the employedsputtering conditions. Switching current of nanoscale devices is smaller while effective anisotropy field is larger for the devices with moreresistive W channeldeposited at lowersputtering power and higher Ar gas pressure. The effective spin Hall angle evaluated from the switching probability varies by a factor of 2 –3 depending on the Wresistivity controlled by thesputtering conditions. (Source: App...
Source: Applied Physics Letters - November 8, 2016 Category: Physics Authors: C. Zhang, S. Fukami, K. Watanabe, A. Ohkawara, S. DuttaGupta, H. Sato, F. Matsukura and H. Ohno Source Type: research
Computational discovery and characterization of polymorphic two-dimensional IV –V materials
First-principles calculations predict the stability andproperties of two-dimensional (2D) group IV –V MX compounds (M = Si,Ge, Sn, Pb; X = P, As, Sb, Bi) in two distinct crystallographic configurations: a low symmetryCm layer inspired by the layered bulkstructures of SiP, SiAs, GeP, and GeAs, and a high symmetryP6¯m2structure previously predicted for 2D SiP. The calculations predict that theCmstructure is more stable for X = As, Sb, and Bi, and theP6¯m2structure for X = P. The electronicproperties of the twostructures are quite different. Specifically, theCmband gaps are systematically larger by abou...
Source: Applied Physics Letters - November 8, 2016 Category: Physics Authors: Michael Ashton, Susan B. Sinnott and Richard G. Hennig Source Type: research
Optical control of plasmonic heating effects using reversible photo-alignment of nematic liquid crystals
We demonstrate and characterize an optical control of theplasmonic heat delivered by a monolayer substrate of gold nanoparticles, obtained by modulating the effectiverefractive index of the neighboringdielectric medium. The effect, which exploits the dependence of thenematic liquid crystal(NLC)refractive index on the molecular director orientation, is realized by using apolarization dependent, light-induced molecular reorientation of a thin film of photo-alignment layer that theNLC is in contact with. For a suitable alignment,plasmonic pumping intensity values ranging from 0.25 W/cm2 to 6.30 W/cm2 can induce up to 17.4 ...
Source: Applied Physics Letters - November 8, 2016 Category: Physics Authors: Giovanna Palermo, Ugo Cataldi, Luciano De Sio, Thomas B ürgi, Nelson Tabiryan and Cesare Umeton Source Type: research
Modifications of plasma density profile and thrust by neutral injection in a helicon plasma thruster
Argon propellant is introduced from the upstream and downstream sides of a high powerhelicon plasma thruster. Theplasma density profile and the imparted thrust aremeasured for various upstream and downstream argonflow rates, where the total gasflow rate of 70 sccm and the resultant vacuum chamberpressure of 0.2 mTorr are maintained. It is observed that the imparted thrust increases with an increase in the downstream gasflow rate; simultaneously an upstream-peaking profile of theplasma density observed for the upstream gas injection becomes uniform for the downstream gas injection. The difference in the thrust between the u...
Source: Applied Physics Letters - November 7, 2016 Category: Physics Authors: Kazunori Takahashi, Yoshinori Takao and Akira Ando Source Type: research
