Blog
- CuInSe2 Quantum Dots Grown By Molecular Beam Epitaxy On Amorphous SiO2 surfaces 13/08/2019 The currently most efficient polycrystalline solar cells are based on the Cu(In,Ga)Se2 compound as a light absorption layer. However, in view of new concepts of nanostructured solar cells, CuInSe2 nanostructures are of high interest. In this work, we report CuInSe2 nanodots grown through a vacuum-compatible co-evaporation growth process on an amorphous surface. The density, mean size, and peak optical emission energy of the nanodots can be controlled by changing the growth temperature. Scanning transmission electron microscopy measurements confirmed the crystallinity of the nanodots as well as chemical composition and structure compatible with tetragonal CuInSe2. Photoluminescence measurements of CdS-passivated nanodots showed that the nanodots are optoelectronically active with a broad emission extending to energies above the CuInSe2 bulk bandgap and in agreement with the distribution of sizes. A blue-shift of the luminescence is observed as the average size of the nanodots gets smaller, evidencing quantum confinement in all samples. By using simple quantum confinement calculations, we correlate the photoluminescence peak emission energy with the average size of the nanodots
- This One 'Anomaly' Is Driving Physicists To Search For Light Dark Matter 12/08/2019 We buy our own products and put them under the same testing methodology so that you can easily compare them.
- Synthesizing Single-Crystalline Hexagonal Graphene Quantum Dots 12/08/2019 The Korea Advanced Institute of Science and Technology (KAIST).
- Large-grain MBE-grown GaSe on GaAs With A Mexican Hat-Like Valence Band Dispersion 11/08/2019 Atomically thin GaSe has been predicted to have a non-parabolic, Mexican hat-like valence band structure due to the shift of the valence band maximum (VBM) near the Γ point which is expected to give rise to novel, unique properties such as tunable magnetism, high effective mass suppressing direct tunneling in scaled transistors, and an improved thermoelectric figure of merit. However, the synthesis of atomically thin GaSe remains challenging. Here, we report on the growth of atomically thin GaSe by molecular beam epitaxy (MBE) and demonstrate the high quality of the resulting van der Waals epitaxial films. The full valence band structure of nominal bilayer GaSe is revealed by photoemission electron momentum microscopy (k-PEEM), confirming the presence of a distorted valence band near the Γ point. Our results open the way to demonstrating interesting new physical phenomena based on MBE-grown GaSe films and atomically thin monochalcogenides in general.
- Researchers Build Quantum Vibration Sensor That Can Measure The Smallest Units Of Sound 10/08/2019 A system that can distinguish phonons, the smallest units of sound, marks an important milestone in the development of more advanced quantum computers.
- Quantum Supremacy Is Coming: Here’s What You Should Know 08/08/2019 Researchers are getting close to building a quantum computer that can perform tasks a classical computer can’t. Here’s what the milestone will mean.
- Quantum Computers To Clarify The Connection Between The Quantum And Classical Worlds 06/08/2019 "The quantum-to-classical transition occurs when you add more and more particles to a quantum system".
- New Research Reveals How Electrons Interact In Twisted Graphene 04/08/2019 With our study, we may have gotten closer to solving the problem of high-temperature superconductivity.
- Scientists Built A Tiny Version Of The Sun In Wisconsin 31/07/2019 What we can learn about our star by using the 'Big Red Ball.'
- Tunnel Barrier Disappears In A Topological Superconducting State 29/07/2019 Researchers have seen Klein tunnelling – a rare relativistic phenomenon in which a tunnel barrier disappears – in a topological superconducting state for the first time.
- Giant Vortex Clusters Appear In 2D Superfluids 27/07/2019 In a classical fluid, such as water or air, flow can be described by a dimensionless number known as the Reynolds number, which expresses the ratio of inertial and viscous forces in the fluid.