A method that can be used to predict the growth of earthquake faults also aids prediction of the tiniest of phenomena--how arrays of "artificial atoms," or quantum dots, assemble and stack themselves on semiconductor materials, National Institute of Standards and Technology (NIST) researchers report in the July 15 issue of Physical Review B.
The insight could aid development of more reliable methods for fabricating lasers, sensors and other devices that exploit quantum dots special electronic properties -- the result of confining electrons in the space of a few nanometers. The minuscule structures already are the basis for some lasers. Yet, difficulties in making quantum dots of uniform size and precisely positioning them on a substrate remain formidable. These obstacles stand in the way of an array of faster, more powerful electronic and photonic devices that require only small inputs of energy to spring into action.
NISTs Bo Yang and Vinod Tewary borrowed a mathematical concept that explains how cracks grow in a solid, such as the Earths crust or an airplane wing. The concept, called the elastic energy release rate, accounts for how energy is apportioned as a crack advances. The scientists found that the rate also accounts for how self-assembling quantum dots, which strain the systems lattice-like atomic geometry, will position and align themselves among their neighbors--those next door and those living below. For cube-shaped quantum dots, at least, the equation predicts the most "energetically favorable" location for a quantum dot. The NIST pair says their theory can be used, for example, to predict the optimal depth for embedding quantum dots that will be overlain by another array of dots.
Mark Bello | EurekAlert!
'Frequency combs' ID chemicals within the mid-infrared spectral region
16.03.2018 | American Institute of Physics
Fraunhofer HHI have developed a novel single-polarization Kramers-Kronig receiver scheme
16.03.2018 | Fraunhofer-Institut für Nachrichtentechnik, Heinrich-Hertz-Institut, HHI
Animal photoreceptors capture light with photopigments. Researchers from the University of Göttingen have now discovered that these photopigments fulfill an...
On 15 March, the AWI research aeroplane Polar 5 will depart for Greenland. Concentrating on the furthest northeast region of the island, an international team...
The world’s second-largest ice shelf was the destination for a Polarstern expedition that ended in Punta Arenas, Chile on 14th March 2018. Oceanographers from...
At the 2018 ILA Berlin Air Show from April 25–29, the Fraunhofer Institute for Laser Technology ILT is showcasing extreme high-speed Laser Material Deposition (EHLA): A video documents how for metal components that are highly loaded, EHLA has already proved itself as an alternative to hard chrome plating, which is now allowed only under special conditions.
When the EU restricted the use of hexavalent chromium compounds to special applications requiring authorization, the move prompted a rethink in the surface...
At the ILA Berlin, hall 4, booth 202, Fraunhofer FHR will present two radar sensors for navigation support of drones. The sensors are valuable components in the implementation of autonomous flying drones: they function as obstacle detectors to prevent collisions. Radar sensors also operate reliably in restricted visibility, e.g. in foggy or dusty conditions. Due to their ability to measure distances with high precision, the radar sensors can also be used as altimeters when other sources of information such as barometers or GPS are not available or cannot operate optimally.
Drones play an increasingly important role in the area of logistics and services. Well-known logistic companies place great hope in these compact, aerial...
16.03.2018 | Event News
13.03.2018 | Event News
08.03.2018 | Event News
16.03.2018 | Earth Sciences
16.03.2018 | Physics and Astronomy
16.03.2018 | Life Sciences