Related papers: Room-temperature excitonic absorption in quantum w…
Excitonic effects in 1D semiconductors can be qualitatively different from those in higher dimensions. In particular, the Sommerfeld factor, the ratio of the above-band-edge excitonic continuum absorption to free electron-hole pair…
The second part of this thesis is concerned with properties of excitons and modelling of excitonic lasing in quasi-one-dimensional quantum wires. I develop a very general numerical method of calculating the properties of wires with…
We ascertain the anisotropic thermal conductivity of alumina passivated black phosphorus (BP), a reactive 2D nanomaterial with strong in-plane anisotropy. We measure the room temperature thermal conductivity by time-domain thermoreflectance…
Thermal conductivity is a critical material property in numerous applications, such as those related to thermoelectric devices and heat dissipation. Effectively modulating thermal conductivity has become a great concern in the field of heat…
We derive fundamental per-channel bounds on angle-integrated absorption and thermal radiation for arbitrary bodies---for any given material susceptibility and bounding region---that simultaneously encode both the per-volume limit on…
We investigate the nonlinear optical response of a commercial extended-wavelength In$_{0.81}$Ga$_{0.19}$As photodetector. Degenerate two-photon absorption in the mid-infrared range is observed at room temperature using a quantum cascade…
The study is focused on the dispersion properties of a wire medium formed by a rectangular lattice of parallel wires at the frequencies close to its plasma frequency. While the effective medium theory predicts isotropic behaviour of…
We present a 21-cm emission-absorption study towards extragalactic sources in the Canadian Galactic Plane Survey (CGPS). We have analyzed HI spectra towards 437 sources with S > 150 mJy, giving us a source density of 0.6 sources per square…
We study the effect of thermal equilibration on the transport properties of a weakly interacting one-dimensional electron system. Although equilibration is severely suppressed due to phase-space restrictions and conservation laws, it can…
The Lloyd model is extended to the exciton problem in quasi one-dimensional structures to study the interplay between the Coulomb attraction and disorder scattering. Within this model the averaging and resummation of the locator series can…
Temperature influences the performance of two-dimensional materials in optoelectronic devices. Indeed, the optical characterization of these materials is usually realized at room temperature. Nevertheless most {\it ab-initio} studies are…
High resolution X-ray spectroscopy of the warm absorber in the nearby quasar, MR2251-178 (z = 0.06398) is presented. The observations were carried out in 2011 using the Chandra High Energy Transmission Grating and the XMM-Newton Reflection…
We study stimulated emission and absorption of gravitons in a squeezed vacuum state immersed in a thermal radiation bath. Employing one-loop interaction-picture perturbation theory, we track the time evolution of the graviton number…
A quantum absorption refrigerator driven by noise is studied with the purpose of determining the limitations of cooling to absolute zero. The model consists of a working medium coupled simultaneously to hot, cold and noise baths. Explicit…
We present the analysis of a new broad-band X-ray spectrum (0.6-180.0 keV) of the radio-quiet quasar MR 2251-178 which uses data obtained with both Suzaku and the Swift/BAT. In accordance with previous observations, we find that the general…
Optical spectroscopy of ultimately thin materials has significantly enhanced our understanding of collective excitations in low-dimensional semiconductors. This is particularly reflected by the rich physics of excitons in atomically thin…
Owing to their small binding energies, excitons in bulk semiconductors typically exhibit a sharp optical peak at low temperatures only. This limitation can be overcome by single-walled carbon nanotubes (SWCNTs) and other low-dimensional…
thermal radiation emitted by a %hot cobalt wire in the temperature range from \(T\approx 400\,\)K up to melting. The radiation is linearly polarized perpendicular to the wire. \(P\) decreases from \(30\,\%\) just above room temperature down…
The thermal conductivity and thermoelectric power of a single carbon nanotube were measured using a microfabricated suspended device. The observed thermal conductivity is more than 3000 W/K m at room temperature, which is two orders of…
To translate electrical into optical signals one uses the modulation of either the refractive index or the absorbance of a material by an electric field. Contemporary electroabsorption modulators (EAMs) employ the quantum confined Stark…