Do you want to publish a course? Click here

Rigid platform for applying large tunable strains to mechanically delicate samples

203   0   0.0 ( 0 )
 Added by Clifford Hicks
 Publication date 2020
  fields Physics
and research's language is English




Ask ChatGPT about the research

Response to uniaxial stress has become a major probe of electronic materials. Tuneable uniaxial stress may be applied using piezoelectric actuators, and so far two methods have been developed to couple samples to actuators. In one, actuators apply force along the length of a free, beam-like sample, allowing very large strains to be achieved. In the other, samples are affixed directly to piezoelectric actuators, allowing study of mechanically delicate materials. Here, we describe an approach that merges the two: thin samples are affixed to a substrate, that is then pressurized uniaxially using piezoelectric actuators. Using this approach, we demonstrate application of large elastic strains to mechanically delicate samples: the van der Waals-bonded material FeSe, and a sample of CeAuSb$_2$ that was shaped with a focused ion beam.



rate research

Read More

The realization of ordered strain fields in two-dimensional crystals is an intriguing perspective in many respects, including the instauration of novel transport regimes and the achievement of enhanced device performances. In this work, we demonstrate the possibility to subject micrometric regions of atomically-thin molybdenum disulphide (MoS2) to giant strains with the desired ordering. Mechanically-deformed MoS2 membranes can be obtained by proton-irradiation of bulk flakes, leading to the formation of monolayer domes containing pressurized hydrogen. By pre-patterning the flakes via deposition of polymeric masks and electron beam lithography, we show that it is possible not only to control the size and position of the domes, but also to create a mechanical constraint. Atomic force microscopy measurements reveal that this constraint alters remarkably the morphology of the domes, otherwise subject to universal scaling laws. Upon the optimization of the irradiation and patterning processes, unprecedented periodic configurations of large strain gradients -- estimated by numerical simulations -- are created, with the highest strains being close to the rupture critical values (> 10 %). The creation of such high strains is confirmed by Raman experiments. The method proposed here represents an important step towards the strain engineering of two-dimensional crystals.
Several pn junctions were constructed from mechanically exfoliated ultrawide bandgap (UWBG) beta-phase gallium oxide (b{eta}-Ga2O3) and p-type gallium nitride (GaN). The mechanical exfoliation process, which is described in detail, is similar to that of graphene and other 2D materials. Atomic force microscopy (AFM) scans of the exfoliated b{eta}-Ga2O3 flakes show very smooth surfaces with average roughness of 0.647 nm and transmission electron microscopy (TEM) scans reveal flat, clean interfaces between the b{eta}-Ga2O3 flakes and p-GaN. The device showed a rectification ratio around 541.3 (V+5/V-5). Diode performance improved over the temperature range of 25{deg}C and 200{deg}C, leading to an unintentional donor activation energy of 135 meV. As the thickness of exfoliated b{eta}-Ga2O3 increases, ideality factors decrease as do the diode turn on voltages, tending toward an ideal threshold voltage of 3.2 V as determined by simulation. This investigation can help increase study of novel devices between mechanically exfoliated b{eta}-Ga2O3 and other materials.
We develop a thermally tunable hybrid photonic platform comprising gallium arsenide (GaAs) photonic crystal cavities, silicon nitride (SiN$_x$) grating couplers and waveguides, and chromium (Cr) microheaters on an integrated photonic chip. The GaAs photonic crystal cavities are evanescently connected to a common bus waveguide, separating the computation and communication layers. The microheaters are designed to continuously and reversibly tune distant photonic crystal cavities to a common resonance. This architecture can be implemented in a coherent optical network for dedicated optical computing and machine learning.
The use of natural or bioinspired materials to develop edible electronic devices is a potentially disruptive technology that can boost point-of-care testing. The technology exploits devices which can be safely ingested, along with pills or even food, and operated from within the gastrointestinal tract. Ingestible electronics could potentially target a significant number of biomedical applications, both as therapeutic and diagnostic tool, and this technology may also impact the food industry, by providing ingestible or food-compatible electronic tags that can smart track goods and monitor their quality along the distribution chain. We hereby propose temporary tattoo-paper as a simple and versatile platform for the integration of electronics onto food and pharmaceutical capsules. In particular, we demonstrate the fabrication of all-printed Organic Field-Effect Transistors (OFETs) on untreated commercial tattoo-paper, and their subsequent transfer and operation on edible substrates with a complex non-planar geometry.
The recent advent of two-dimensional monolayer materials with tunable optoelectronic properties and high carrier mobility offers renewed opportunities for efficient, ultra-thin excitonic solar cells alternative to those based on conjugated polymer and small molecule donors. Using first-principles density functional theory and many-body calculations, we demonstrate that monolayers of hexagonal BN and graphene (CBN) combined with commonly used acceptors such as PCBM fullerene or semiconducting carbon nanotubes can provide excitonic solar cells with tunable absorber gap, donor-acceptor interface band alignment, and power conversion efficiency, as well as novel device architectures. For the case of CBN-PCBM devices, we predict the limit of power conversion efficiencies to be in the 10 - 20% range depending on the CBN monolayer structure. Our results demonstrate the possibility of using monolayer materials in tunable, efficient, polymer-free thin-film solar cells in which unexplored exciton and carrier transport regimes are at play.
comments
Fetching comments Fetching comments
Sign in to be able to follow your search criteria
mircosoft-partner

هل ترغب بارسال اشعارات عن اخر التحديثات في شمرا-اكاديميا