AlGaN-based ultraviolet (UV) light sources have recently attracted much research interest due to their potential candidate to replace excimer and mercury lamps. However, their output power is limited by the inefficient p-type doping at high Al composition AlGaN. In this talk, we will report on the electron-beam-pumped UV light sources, where multiple ultrathinGaN wells are used to enhance the internal quantum efficiency and to reach deep UV range such as 230 nm. And UV light source with wavelength varing from 285-232 nm with corresponded output power of 23-160 mW have been achieved under pulse mode.
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.
We report the molecular beam epitaxial growth of InSb quantum dots (QD) inserted as sub-monolayers in an InAs matrix
and grown using Sb2 and As2 fluxes. These InSb QD nanostructures exhibit intense mid-infrared photoluminescence up
to room temperature. The nominal thickness of the sub-monolayer insertions can be controlled by the growth
temperature (TGr = 450-320 °C) which gives rise to the variation of the emission wavelength within the 3.6-4.0 μm range
at room temperature. Light emitting diodes where fabricated using ten InSb QD sheets and were found to exhibit bright
electroluminescence with a single peak at 3.8 μm at room temperature. A comparative analysis of the optical properties
of the structures grown using (Sb2,As2) and (Sb4,As4) is also presented.
KEYWORDS: Semiconductor lasers, Semiconductors, Electron beams, Stereolithography, Quantum wells, Near field optics, Optical pumping, Waveguides, Near field, Cladding
Characteristics of low-threshold ZnSe-based room-temperature green semiconductor alsers are studied in detail as dependent on transverse size (h) of an active region. It is shown that the efficiency increases with increasing h, then passes through a maximum, and gradually falls down when h exceeds the cavity length L. The effect can be explained by taking into account the excitation of different transversal modes.
Optical properties of ZnO doped with Mn and V were studied. Zn(Mn)O layers were grown by peroxide MBE, and Zn(V)O was prepared by high-dose ion implantation of bulk ZnO prepared by hydrothermal technique. The Zn(Mn)O layers containing up to 50% of Mn were characterized by high-resolution x-ray diffraction, photoluminescence, and optical absorption. A blue shift of the band edge revealed from optical absorption measurements points to the incorporation of at least a part of Mn atoms on the lattice sites. An increase in the Zn(Mn)O band gap and an enhancement of the broad below band gap absorption associated with Mn ions were observed with increasing Mn composition. Correlating structural and optical transmission data, we suggest that the band edge of Zn(Mn)O rises linearly with the amount of Mn ions substituting Zn on the lattice sites. Photoluminescence of ZnO moderately doped with Mn shows several emission lines (the strongest ones are located at 3.34 and 3.36 eV). Surprisingly, no shift in the near-band-edge emission (3.36 eV) was detected in the photoluminescence data. Photoluminescence excitation studies revealed that the near-band-edge peak and the peak centered around 3.34 eV have different origin. Most probably, the second line is due to Mn intracenter transitions. Photoluminescence studies of ZnO bulk samples implanted with V+ have revealed that thermal annealing at 800 °C restores to a large extent the optical quality of the material. A new emission line centered at 3.307 eV has been found in the photoluminescence spectrum of the highly conductive samples implanted with a V dose of 1 × 1016 cm-2.
AlGaAsSb/AlGaSb heterostructures offer the ability to realize high-performance devices for 1550 nm high-speed optical interconnect applications. In this context, we present the design, fabrication, integration and characterization of 10 GHz p-i-n photodetectors in this material system. This effort has involved an investigation into inductively coupled plasma (ICP) etching of these materials and the development of a novel process for their conductive polymer based flip chip die attach.
The intensive up-conversion photoluminescence (UPL) was observed at low temperatures in CdSe/ZnSe structures with single CdSe inserts of a nominal thickness of 1.5 and 0.6 ML. The quadratic-like dependence of UPL intensity on the excitation power was obtained. UPL mechanism was interpreted on the basis of non-linear process of two-step two-photon absorption (TS-TPA) through deep defect states including cation vacancies localized at the barier-nanoisland heterointerface.
The photoluminescence (PL) and PL excitation (PLE) spectra of quantum wells (QWs) formed by CdSe insertions in ZnSe matrix reveal the states of heavy and light excitons localized in CdSe-rich islands, and the energy EME which is associated with the percolation threshold over the entire lateral plane of QW. The model calculations are performed which result in evaluation of the island mean size and composition of ZnCdSe solid solution within and outside of islands.
V. Davydov, A. Klochikhin, Vadim Emtsev, A. Sakharov, S. Ivanov, V. Vekshin, Friedhelm Bechstedt, J. Furthmueller, Jochen Aderhold, Jurgen Graul, A. Mudryi, H. Harima, A. Hashimoto, A. Yamamoto, J. Wu, Henning Feick, Eugene Haller
We present results of photoluminescence studies of the band gap of non-intentionally doped single-crystalline hexagona InN layers and In-rich InxGa1-xN alloy layers (0.36 < x < 1). The band gap of InN is found to be close to 0.7 eV. This is much smaller than the values of 1.8 eV to 2.1 eV cited in the current literature. A bowing parameter of b ≈ 2.5 eV allows one to reconcile our and the literature data for the band gap values of InxGa1-xN alloys in the entire composition region.
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