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Terahertz quantum cascade laser sources based on intra-cavity difference frequency generation from mid-IR devices are an important asset for applications in rotational molecular spectroscopy and sensing, beingthe only electrically pumped…
Silicon-germanium heterostructures have successfully hosted quantum dot qubits, but the intrinsic near-degeneracy of the two lowest valley states poses an obstacle to high fidelity quantum computing. We present a modification to the Si/SiGe…
A study of the mechanisms responsible for the infra-red to near infra-red up-conversion in Tm3+-doped silica fibers is presented. Upconversion luminescence was observed from the 3H4 level of Tm3+ under 1586 nm pumping into the 3F4 level.…
2DEG states of Al/$\delta$-GaAs structures were investigated in the persistent tunneling photoconductivity (PTPC) regime at low temperatures. "Thickening" of the unoccupied subbands to the ground state of 2DEG was observed at $T=4.2$~$K$.…
Bubble formation in liquid xenon underneath a Thick Gaseous Electron Multiplier (THGEM) electrode immersed in liquid xenon was observed with a CCD camera. With voltage across the THGEM, the appearance of bubbles was correlated with that of…
In this work we investigate the effect of gamma and ultraviolet radiations on the thermoluminescence of Brazilian calcite. The irradiated samples presented three TL peaks at 150, 245 and 320^oC (at a linear heating rate of 1.8^oC/s), with a…
Van der Waals heterostructures comprised of two-dimensional (2D) materials offer a platform to obtain materials by design with unique electronic properties. Franckeite (Fr) is a naturally occurring van der Waals heterostructure comprised of…
Issues of Ge hut array formation and growth at low temperatures on the Ge/Si(001) wetting layer are discussed on the basis of explorations performed by high resolution STM and in-situ RHEED. Data of HRTEM studies of multilayer Ge/Si…
Fe K-edge and Se K-edge x-ray absorption near edge structure (XANES) measurements are used to study FeSe$_{1-x}$Te$_{x}$ electronic structure of chalcogenides. An intense Fe K-edge pre-edge peak due to Fe 1s$\to$3d (and admixed Se/Te $p$…
Electron spin qubits in Si/SiGe quantum wells are limited by the small and variable energy separation of the conduction band valleys. While sharp quantum well interfaces are pursued to increase the valley splitting energy deterministically,…
SiAlON is a prominent example of systems suitable as hosts for creating materials for light-emitting diodes (LEDs). In this work, the electronic structure of a series of semiordered and disordered SiAlON systems is investigated by means of…
The low-energy band-structure of electrons propagating on a lateral surface of a heterostructure consisting of three dimensional topological insulator (TI) and magnetic insulator layers has been calculated. The energy spectrum is highly…
Spectroscopic identification of distinct nonlinear photocurrents unveils quantum geometric properties of electron wavefunctions and the momentum-space topological structures. This is especially interesting, but still puzzling, for chiral…
The p-n diodes represent the most fundamental device building block for diverse optoelectronic functions, but are difficult to achieve in atomically thin transition metal dichalcogenides (TMDs) due to the inability to selectively dope them…
An ab-initio pseudopotential calculation using density functional theory within the local density approximation has been performed to investigate the electronic properties of TlSe which is of chain-like crystal geometry. The energy bands…
For designing an efficient terahertz (THz) emitter, the defect density of the semiconductors is smartly increased to reduce carrier lifetime, which subsequently lowers the overall power output of the semiconductor. To overcome this…
We demonstrate laser frequency stabilization to excited state transitions using cascade electromagnetically induced transparency (EIT). Using a room temperature Rb vapor cell as a reference, we stabilize a first diode laser to the D2…
We have fabricated highly-luminescent samples with erbium-doped amorphous silicon sub-oxide (a-SiOx<Er>) layers on SiO2/Si substrates. The layers are designed to provide a resonance with large modal overlap with the active material and with…
Electronic structure calculations for layered zincblende semiconductors are described within a restricted basis formalism which naturally and non-perturbatively accomodates both crystalline inversion asymmetry and cubic anisotropy. These…
The structural and optical properties of 3 different kinds of GaAs nanowires with 100% zinc-blende structure and with an average of 30% and 70% wurtzite are presented. A variety of shorter and longer segments of zinc-blende or wurtzite…