Related papers: Excitons under strain: light absorption and emissi…
The signature of defects in the optical spectra of hexagonal boron nitride (BN) is investigated using many body perturbation theory. A single BN-sheet serves as a model for different layered BN- nanostructures and crystals. In the sheet we…
We show that the optical absorption spectra of boron nitride (BN) nanotubes are dominated by strongly bound excitons. Our first-principles calculations indicate that the binding energy for the first and dominant excitonic peak depends…
The optical properties of silicon can be greatly tuned by applying strain and opening new perspectives, particularly in applications where infrared is key. In this work, we use a recent model for the indirect light absorption of silicon and…
Low temperature photoluminescence spectra of a color center in hexagonal boron nitride are analyzed. The acoustic phonon sideband can be described by a deformation coupling proportional to strain to a phonon bath that is effectively two…
We calculate the binding energy, transition energies, oscillator strength, and absorption coefficient of indirect excitons in transition metal dichalcogenide (TMDC) double layers separated by an integer number of hexagonal boron nitride…
Biased bilayer graphene (BBG) is a variable band gap semiconductor, with a strongly field-dependent band gap of up to $300 \, \text{meV}$, making it of particular interest for graphene-based nano-electronic and -photonic devices. The…
The two-dimensional material hexagonal boron nitride (hBN) hosts luminescent centres with emission energies of 2 eV which exhibit pronounced phonon sidebands. We investigate the microscopic origin of these luminescent centres by combining…
The isotopic mass of constituent elements of materials has a well-known effect on the energy of vibrational modes. By means of monochromated scanning transmission electron microscopy we have experimentally studied the phonon bandstructure…
Strongly anisotropic media where the principal components of the dielectric tensor have opposite signs are called hyperbolic. Such materials length exhibit unique nanophotonic properties enabled by the highly directional propagation of…
Polarization-dependent two-dimensional Fourier-transform spectroscopy (2DFTS) is performed on excitons in strained bulk GaAs layers probing the coherent response for differing amounts of strain. Biaxial tensile strain lifts the degeneracy…
Hexagonal boron nitride (hBN) has been attracting great attention because of its strong excitonic effects. Taking into account few-layer systems, we investigate theoretically the effects of the number of layers on quasiparticle energies,…
Accessing mid-infrared radiation is of great importance for a range of applications, including thermal imaging, sensing, and radiative cooling. Here, we study light interaction with hexagonal boron nitride nanocavities and reveal strong and…
We observe a series of sharp resonant features in the differential conductance of graphene-hexagonal boron nitride-graphene tunnel transistors over a wide range of bias voltages between $\sim$10 and 200 mV. We attribute them to electron…
Excitons -- elementary excitations formed by bound electron-hole pairs -- govern the optical properties and excited-state dynamics of materials. In two-dimensions (2D), excitons are theoretically predicted to have a linear energy-momentum…
Polaritons in two-dimensional materials provide extreme light confinement that is difficult to achieve with metal plasmonics. However, such tight confinement inevitably increases optical losses through various damping channels. Here we…
A quantitative analysis of the excitonic luminescence efficiency in hexagonal boron nitride (hBN) is carried out by cathodoluminescence in the ultraviolet range and compared with zinc oxide and diamond single crystals. A high quantum yield…
The photoluminescence (PL) spectrum of transition metal dichalcogenides (TMDs) shows a multitude of emission peaks below the bright exciton line and not all of them have been explained yet. Here, we study the emission traces of…
Phonon-assisted photoluminescence (PL) in molybdenum-based two-dimensional dichalcogenides is typically weak due to the dormant phonon coupling with optically inactive momentum-dark (intervalley) excitons, unlike in tungsten-based…
Optical properties of heterostructures composed of layered 2D materials, such as transition metal dichalcogenides (TMDs) and graphene, are broadly explored. Of particular interest are light-induced energy transfer mechanisms in these…
The effects of the electron-phonon interaction on optical excitations can be understood in terms of exciton-phonon coupling, and require a careful treatment in low-dimensional materials with strongly bound excitons or strong electron-hole…