933 research outputs found
Television in India : satellites, politics, and cultural change
No full textIntroduction: satellite television, identity and globalisation in contemporary India / Nalin Mehta - The Mahatma didn’t like the movies and why it matters: Indian broadcasting policy, 1920s–1990s / Robin Jeffrey - India talking: politics, democracy and news television / Nalin Mehta - Politics without television: the BSP and the Dalit counter-public sphere / Maxine Loynd - Muslims on television: news and representation on satellite channels / Roshni Sengupta - ‘Give me a vote, and I will give you a TV set’: television in Tamil Nadu politics / Maya Ranganathan - Soaps, serials and the CPI(M), cricket beats them all: cricket and television in contemporary India / Boria Majumdar - Bowling with the wind: a television producer’s view on cricket and satellite TV in contemporary India / Peter HuttonPETER - Changing contexts, new texts: ‘‘inserting’’ TV into the transforming text of post-1980 Bengali cinema / Sharmistha Goopt
Unravelling stacking order in epitaxial bilayer MX<sub>2</sub>using 4D-STEM with unsupervised learning
No full textFollowing an extensive investigation of various monolayer transition metal dichalcogenides (MX2), research interest has expanded to include multilayer systems. In bilayer MX2, the stacking order strongly impacts the local band structure as it dictates the local confinement and symmetry. Determination of stacking order in multilayer MX2 domains usually relies on prior knowledge of in-plane orientations of constituent layers. This is only feasible in case of growth resulting in well-defined triangular domains and not useful in-case of closed layers with hexagonal or irregularly shaped islands. Stacking order can be discerned in the reciprocal space by measuring changes in diffraction peak intensities. Advances in detector technology allow fast acquisition of high-quality four-dimensional datasets which can later be processed to extract useful information such as thickness, orientation, twist and strain. Here, we use 4D scanning transmission electron microscopy combined with multislice diffraction simulations to unravel stacking order in epitaxially grown bilayer MoS2. Machine learning based data segmentation is employed to obtain useful statistics on grain orientation of monolayer and stacking in bilayer MoS2.sponsorship: J.V. acknowledges funding from FLAG-ERA JTC2017 project 'Graph-Eye'. N.G. acknowledges funding from GOA project 'Solarpaint' of the University of Antwerp. This project has received funding from the European Union's Horizon 2020 research and innovation programme under Grant Agreement No. 823717-ESTEEM3. 4D STEM data was acquired on a hybrid pixel detector funded with a Hercules fund 'Direct electron detector for soft matter TEM' from the Flemish Government. M. N. acknowledges funding from a Marie Curie Fellowship agreement No 838001. We thank Dr Jiongjiong Mo and Dr Benjamin Groven for developing the CVD-MoS2 growth on sapphire and providing the material used in this article. (FLAG-ERA JTC2017 project 'Graph-Eye', GOA project 'Solarpaint' of the University of Antwerp, European Union's Horizon 2020 research and innovation programme|823717-ESTEEM3, Hercules fund 'Direct electron detector for soft matter TEM' from the Flemish Government, Marie Curie Fellowship|838001, Marie Curie Actions (MSCA)|838001)status: Publishe
Unravelling Grain Orientation and Stacking Order in Bilayer MoS2 Using Electron Diffraction
No full textC. C. Mehta
No full textOn the life and works of Chandravadan Chimanlal Mehta, b. 1901, Gujarati author
High-Density Patterning of InGaZnO by CH<sub>4</sub>: a Comparative Study of RIE and Pulsed Plasma ALE
No full text
Chemical vapor deposition of monolayer-thin WS2 crystals from the WF6 and H2S precursors at low deposition temperature
No full textMonolayer-thin WS2 with (0002) texture grows by chemical vapor deposition (CVD) from gas-phase precursors WF6 and H2S at a deposition temperature of 450 °C on 300 mm Si wafers covered with an amorphous Al2O3 starting surface. We investigate the growth and nucleation mechanism during the CVD process by analyzing the morphology of the WS2 crystals. The CVD process consists of two distinct growth regimes. During (i) the initial growth regime, a fast and self-limiting reaction of the CVD precursors with the Al2O3 starting surface forms predominantly monolayer-thin WS2 crystals and AlF3 crystals that completely cover the starting surface. During (ii) the steady-state growth regime, a much slower, anisotropic reaction on the bottom, first WS2 layer proceeds with the next WS2 layer growing preferentially in the lateral dimensions. We propose that the precursor adsorption reaction rate strongly diminishes when the precursors have no more access to the Al2O3 surface as soon as the WS2 layer completely covers the Al2O3 surface and that the WS2 crystal basal planes and AlF3 crystals have a low reactivity for WF6 adsorption at 450 °C. Nonetheless, a second layer of WS2 starts to form before the first WS2 layer completely covers the starting surface, albeit the surface coverage of the second layer is low (<20%, after 25 min of CVD reaction). During the steady-state growth regime, predominantly the WS2 crystals in the second monolayer continue to grow in lateral dimensions up to ∼40 nm. These crystals reach larger lateral dimensions compared to the crystals in the bottom, first layer due to low reactivity for WF6 adsorption on the WS2 basal plane compared to Al2O3. Presumably, they grow laterally by precursor species that adsorb on and diffuse across the WS2 surface, before being incorporated at the more reactive edges of the WS2 crystals in the second layer. Such a process proceeds slowly with only up to 40% surface coverage of the second WS2 layer after 150 min of CVD reaction. The CVD reaction is mediated by the starting surface: WF6 precursor preferentially adsorbs on Al2O3, whereas adsorption is not observed on SiO2. Nevertheless, WS2 grows on SiO2 in close proximity to Al2O3 in 90 nm pitch Al2O3/SiO2 line patterns. Hence, functionalization of the starting surface (e.g., SiO2 with Al2O3) can provide opportunities to grow monolayer-thin WS2 crystals at predetermined locations by selective, lateral growth with tunable crystal size, even at low deposition temperatures.sponsorship: The authors acknowledge Johan Meersschaut, Thomas Nuytten, Thierry Conard, Danielle Vanhaeren, and Christa Vrancken for RBS, Raman and PL, XPS, AFM, and SEM measurements, respectively. We are grateful to the Agency for Science and Innovation in Flanders (VLAIO, former IWT) under Project No. 141640 and the imec Industrial Affiliation Beyond CMOS program for the financial support. (Agency for Science and Innovation in Flanders (VLAIO)|141640, imec Industrial Affiliation Beyond CMOS program)status: Publishe
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