Alexey A. Toropov

High-Output-Power Ultraviolet Light Source from Quasi-2D GaN Quantum Structure.

Quasi-2D GaN layers inserted in an AlGaN matrix are proposed as a novel active region to develop a high-output-power UV light source. Such a structure is successfully achieved by precise control in molecular beam epitaxy and shows an amazing output power of ≈160 mW at 285 nm with a pulsed electron-beam excitation. This device is promising and competitive in non-line-of-sight communications or the sterilization field.

Plasmonic effects in In(Ga)N

This paper reports on two plasmonic systems based on III-Nitrides: (i) InGaN - Au nanoparticles; (ii) InN with spontaneously formed buried In nanoparticles. By using NSOM and μ-PL studies we established necessary conditions for the efficient interaction of localized plasmons excited in a gold nanoparticle with localized excitons situated near the InGaN surface. The tens-fold PL intensity enhancement was observed for ~100 nm Au nanoparticles. The narrow lines of single excitons have been registered at low temperature. Due to specific thermodynamic properties of InN, its optical properties are strongly influenced by plasmons in spontaneously formed In nanoparticles. The μ-CL study of MBE grown InN/In structures with intentional periodic 0-48 ML In insertions has shown that the bright CL spots (peaked spectrally at ~0.7eV) coincide always with the agglomerates of In nanoparticles. The intensity increase by the factor of ~102 is in good agreement with calculations of the average enhancement factor in InN/In nanocomposites comprising the nanoparticles of an arbitrary shape and orientation. Time-resolved PL studies have demonstrated pronounced Purcell effect, i.e. significant shortening of spontaneous recombination rate, in both systems. Terahertz emission (~3 THz) observed in InN epilayers under electrical pumping is ascribed to surface plasmon polariton waves coupled to electromagnetic field at quasi-periodical structural imperfections.

Electron Spin Alignment in InSb Type‐II Quantum Dots in an InAs Matrix

Electronic spin polarization up to 100 % has been observed in type‐II narrow‐gap heterostructures with InSb quantum dots in an InAs matrix via investigation of circular‐polarized photoluminescence at external magnetic field applied in Faraday geometry. Energy spectrum of holes confined in monolayer scale InSb/InAs quantum well is calculated using tight‐binding approach. The observed effect is explained in terms of strong Zeeman splitting of electrons in InAs matrix due to their large intrinsic g‐factor and corresponding optical transition selection rules. Temperature dependence of polarization degree well fit obtained data providing its experimental verification of suggested model.

GaAs in GaSb: a new type of heterostructure emitting at 2 μm wavelength

We report growth as well as optical and structural studies of a new type of a GaAs/GaSb heterostructure, with 1–3 monolayer thick GaAs layers embedded within unstrained GaSb. In such structures the GaAs layer is under tensile stress, in contrast to the situation in which self-organized growth of quantum dots is commonly observed. The structure emits light in the 2xa0μm wavelength range. The emission characteristics are explained by a combination of quantum confinement effects and localization on nanoscale potential fluctuations.