143 research outputs found
Anisotropic optical gain in m-plane InxGa1-xN/GaN multiple quantum well laser diode wafers fabricated on the low defect density freestanding GaN substrates
Improvements in quantum efficiency of excitonic emissions in ZnO epilayers by the elimination of point defects
科研費報告書収録論文(課題番号:18350092/研究代表者:大友明/高効率酸化亜鉛系青色・紫外発光素子の開発
Light polarization characteristics of m-plane AlxGa1-xN films suffering from in-plane anisotropic tensile stresses
Effects of macroscopic polarization in III-V nitride multi-quantum-wells
Huge built-in electric fields have been predicted to exist in wurtzite III-V
nitrides thin films and multilayers. Such fields originate from heterointerface
discontinuities of the macroscopic bulk polarization of the nitrides. Here we
discuss the background theory, the role of spontaneous polarization in this
context, and the practical implications of built-in polarization fields in
nitride nanostructures. To support our arguments, we present detailed
self-consistent tight-binding simulations of typical nitride QW structures in
which polarization effects are dominant.Comment: 11 pages, 9 figures, uses revtex/epsf. submitted to PR
Optical properties of nearly stacking-fault-free m-plane GaN homoepitaxial films grown by metal organic vapor phase epitaxy on low defect density freestanding GaN substrates
Improved characteristics and issues of m-plane InGaN films grown on low defect density m-plane freestanding GaN substrates by metalorganic vapor phase epitaxy
Electron-phonon renormalization of the absorption edge of the cuprous halides
Compared to most tetrahedral semiconductors, the temperature dependence of
the absorption edges of the cuprous halides (CuCl, CuBr, CuI) is very small.
CuCl and CuBr show a small increase of the gap with increasing
temperature, with a change in the slope of vs. at around 150 K: above
this temperature, the variation of with becomes even smaller. This
unusual behavior has been clarified for CuCl by measurements of the low
temperature gap vs. the isotopic masses of both constituents, yielding an
anomalous negative shift with increasing copper mass. Here we report the
isotope effects of Cu and Br on the gap of CuBr, and that of Cu on the gap of
CuI. The measured isotope effects allow us to understand the corresponding
temperature dependences, which we also report, to our knowledge for the first
time, in the case of CuI. These results enable us to develop a more
quantitative understanding of the phenomena mentioned for the three halides,
and to interpret other anomalies reported for the temperature dependence of the
absorption gap in copper and silver chalcogenides; similarities to the behavior
observed for the copper chalcopyrites are also pointed out.Comment: 14 pages, 5 figures, submitted to Phys. Rev.
Recombination dynamics of a 268nm emission peak in Al0.53In0.11Ga0.36N∕Al0.58In0.02Ga0.40N multiple quantum wells
Recombination dynamics of the 268 nm photoluminescence (PL) peak in a quaternary Al0.53In0.11Ga0.36N/Al0.58In0.02Ga0.40N multiple quantum well (MQW) grown on relaxed AlGaN templates were studied. Although the polarization field in the compressively strained Al0.53In0.11Ga0.36N wells was as high as 1.6 MV/cm, the value of integrated PL intensity at 300 K divided by that at 8 K (eta(int)) was as high as 1.2%. The value was similar to that obtained for the 285 nm PL peak in an Al0.30Ga0.70N/Al0.70Ga0.30N MQW (1.3%), though the A1N molar fraction in the wells was higher by a factor of 1.7. According to these results and the fact that time-resolved PL signal exhibited a stretched exponential decay shape, the improved eta(int) of the AlInGaN wells was attributed to a beneficial effect of the exciton localization as is the case with InGaN alloys; doping or alloying with InN was confirmed to work also on AlGaN in improving eta(int) to realize deep UV optoelectronic devices
Quantum-confined Stark effects in the m-plane In0.15Ga0.85N/GaN multiple quantum well blue light-emitting diode fabricated on low defect density freestanding GaN substrate
Free and bound exciton fine structures in AlN epilayers grown by low-pressure metalorganic vapor phase epitaxy
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