43 research outputs found
Identification of main contributions to conductivity of epitaxial InN
Complex effect of different contributions (spontaneously formed In
nanoparticles, near-interface, surface and bulk layers) on electrophysical
properties of InN epitaxial films is studied. Transport parameters of the
surface layer are determined from the Shubnikov-de Haas oscillations measured
in undoped and Mg-doped InN films at magnetic fields up to 63 T. It is shown
that the In nanoparticles, near-interface and bulk layers play the dominant
role in the electrical conductivity of InN, while influence of the surface
layer is pronounced only in the compensated low-mobility InN:Mg films
Mie-resonances, infrared emission and band gap of InN
Mie resonances due to scattering/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 currently accepted 0.7 eV. Micro-cathodoluminescence
studies complemented by imaging of metallic In have shown that bright infrared
emission at 0.7-0.8 eV arises from In aggregates, and is likely associated with
surface states at the metal/InN interfaces.Comment: 4 pages, 5 figures, submitted to PR
Ultraviolet stimulated emission in AlGaN layers grown on sapphire substrates using ammonia and plasma-assisted molecular beam epitaxy
Ammonia and plasma‐assisted (PA) molecular beam epitaxy modes are used to grow AlN and AlGaN epitaxial layers on sapphire substrates. It is determined that the increase of thickness of AlN buffer layer grown by ammonia‐MBE from 0.32 μm to 1.25 μm results in the narrowing of 101 X‐Ray rocking curves whereas no clear effect on 002 X‐Ray rocking curve width is observed. It is shown that strong GaN decomposition during growth by ammonia‐MBE causes AlGaN surface roughening and compositional inhomogeneity, which leads to deterioration of its lasing properties. AlGaN layers grown by ammonia‐MBE at optimized temperature demonstrate stimulated emission (SE) peaked at λ = 330 nm, 323 nm, 303 nm and 297 nm with the SE threshold values of 0.7 MW cm−2, 1.1 MW cm−2, 1.4 MW cm−2 and 1.4 MW cm−2, respectively. In comparison to these, AlGaN layer grown using PA‐MBE pulsed modes (migration‐enhanced epitaxy, metal‐modulated epitaxy, and droplet elimination by thermal annealing) shows a SE with a relatively low threshold (0.8 MW cm−2) at the considerably shorter wavelength of λ = 267 nm
Использование новых технических средств, связанных со сканированием сложных 3D-объектов, в обучающем процессе технологических знаний
Материалы XI Междунар. науч. конф. студентов, аспирантов и молодых ученых, Гомель, 17-18 мая 2018 г