Studying the atomic structure of intrinsic defects in two-dimensional transition-metal dichalcogenides is difficult since they damage quickly under the intense electron irradiation in transmission electron microscopy (TEM). However, this can also lead to insights into the creation of defects and their atom-scale dynamics. We first show that MoTe2 monolayers without protection indeed quickly deg...

VCSELs with two-sided emission have been presented in the literature long times ago (see, e.g., [1]). In the common AlGaAs material system on GaAs substrates, this is most easily achieved with the use of compressively strained InGaAs quantum wells (QWs) which have a reduced bandgap energy and with current supply through a top ring contact and a bottom ring contact at the back side of the substr...

We report on the effect of GaN buffer threading dislocation (TD) optimization and InGaN/GaN quantum well (QW) hydrogen ðH2Þ treatment on the efficiency of GaN light emitting diodes (LEDs) operating in the spectral range from 400 to 500 nm. A tenfold reduction of the TD density in the GaN buffer increased the efficiency of blue LEDs operating at high current density, while in green LEDs it had v...

In existing flip-chip LED simulations, the light extraction efficiency is related to multiple quantum well (MQW) metal reflector distance because of optical interference. We calculate contrast using several typical intensity distributions among QWs in MQW. The coherence obtained analytically. When luminosity each QW equal, ∼0, meaning incoherent, contrary traditional studies. spatial important ...

The search for methods to produce structures highly organized at the atomic scale during epitaxy is an active research area since it holds the promise for basic discoveries and novel technological applications. Along with the well known kinetic and thermodynamic parameters, it was recently found that Quantum Size Effects can play a crucial role during epitaxial growth [1-3]. For instance, metal...

Stacking Faults (SFs) are important crystal defects in 4H-SiC [1]. They can be electrically active and, in this case, behave as deep quantum well (QW) traps for electrons [2]. This leads to the degradation of high voltage bipolar diodes [3]. The basic origin of SFs in SiC is the small total energy difference between two different polytypes. The net consequence is that they can appear spontaneou...

A new approach for enhancing the exciton absorption and increasing the saturation limit in quantum wells (QWs), using tensile strain, is proposed. Because of the valence-band mixing in a strained QW, the in-plane hole mass can become very large or negative. This leads to a heavy electron-hole reduced mass (exciton mass), and therefore to a small exciton radius. Exciton absorption is substantial...

A discrete-time Quantum Walk (QW) is essentially an operator driving the evolution of a single particle on the lattice, through local unitaries. Some QWs admit a continuum limit, leading to well-known physics partial differential equations, such as the Dirac equation. We show that these simulation results need not rely on the grid: the Dirac equation in (2+1)–dimensions can also be simulated, t...

Efficiency droop is a major obstacle facing high-power application of InGaN/GaN quantum-well (QW) light-emitting diodes (LEDs). In this paper, we report the suppression of efficiency droop induced by the process of density-activated defect recombination in nanorod structures of a-plane InGaN/GaN QWs. In the high carrier density regime, the retained emission efficiency in a dry-etched nanorod sa...

We calculate the energy dispersion relations in Si quantum wells (QW), E(k2D), and quantum wires (QWR), E(k1D), focusing on the regions with negative effective mass (NEM) in the valence band. The existence of such NEM regions is a necessary condition for the current oscillations in ballistic quasineutral plasma in semiconductor structures. The frequency range of such oscillations can be extende...