Two-Dimensional Excitons in Multiple GaN/AlN Monolayer Quantum Wells

JETP Letters - The decay kinetics of low-temperature exciton photoluminescence in a heterostructure with multiple GaN/AlN monolayer quantum wells, which is prepared by molecular beam epitaxy, is...     

Multifunction metal-semiconductor nanocomposites

The basic properties of metal-semiconductor nanocomposites were investigated using InN/In with In clusters as an example. Inconsistencies in the characteristic energies of optical processes occurring in these materials were revealed, and a model is proposed to describe the averaged enhancement by localized plasmons. The possibility of obtaining intense emission in the near infrared and terahertz ranges is demonstrated.     

AlGaN nanostructures with extremely high quantum yield at 300 K

Theoretical optimization of a quantum well heterostructure based on AlGaN solid solutions is implemented in order to attain the maximum charge carrier activation energy and the maximum exciton binding energy at a radiation wavelength of ~300 nm. An optimized structure sample with the radiative recombination dominating over the temperature range of 5 to 300 K and the room temperature internal quantum yield as high as 80% of the value measured at 5 K has been manufactured via plasma-assisted molecular beam epitaxy.     

Growth of thick AlN epilayers with droplet-free and atomically smooth surface by plasma-assisted molecular beam epitaxy using laser reflectometry monitoring

Low-temperature (<750 °C) growth of thick AlN epilayers on c-sapphire by plasma-assisted molecular-beam epitaxy under the Al-rich conditions (F_Al/F_N?<1.4) is reported here. Short periodic Al-flux interruptions controlled precisely by laser reflectometry ensure continuous growth of droplet-free and atomically smooth AlN films (rms<2 ML over 4 μm²) with a growth rate governed by the activated nitrogen flux. Lateral spreading of small accumulated Al clusters with their subsequent incorporation into the AlN layer during the Al-flux interruptions is supposed to be facilitated by activated nitrogen radicals. Strong influence of the remaining Al droplets on the subsequent growth of AlGaN/AlN superlattices is also demonstrated.     

Mie resonances, infrared emission, and the band gap of InN

Mie resonances due to scattering or absorption of light in InN-containing clusters of metallic In may have been erroneously interpreted as the infrared band gap absorption in tens of papers. Here we show by direct thermally detected optical absorption measurements that the true band gap of InN is markedly wider than the currently accepted 0.7 eV. Microcathodoluminescence studies complemented by the imaging of metallic In have shown that bright infrared emission at 0.7-0.8 eV arises in a close vicinity of In inclusions and is likely associated with surface states at the metal/InN interfaces.