98 research outputs found
Implementation of a national guideline for analgesia and sedation: how often can a RASS of 0 to -2 be achieved?
Comparison of the RAMSAY score and the Richmond Agitation Sedation Score for the measurement of sedation depth
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Origin of a-plane (Al,Ga)N formation on patterned c-plane AIN/sapphire templates
a-plane (Al,Ga)N layers can be grown on patterned c-plane AlN/sapphire templates with a ridge direction along [1bar 100]Al2O3. Scanning nanobeam diffraction reveals that the formation of a-plane layers can be explained by nucleation of c-plane (Al,Ga)N with [11bar 20](Al,Ga)N[0001]Al2O3 at the ridge sidewalls. Faster growth of the top (11bar 20)(Al,Ga)N facet in the vertical direction leads to the overgrowth of c-plane (Al,Ga)N nucleated on the horizontal ridge and trench surfaces. Phase separation into binary GaN and AlN takes place during the first growth stages. However, this fades out and does not influence the composition of the final thick a-plane (Al,Ga)N layer
Band gap renormalization in photoexcited semiconductor quantum wire structures in the GW approximation
We investigate the dynamical self-energy corrections of the electron-hole
plasma due to electron-electron and electron-phonon interactions at the band
edges of a quasi-one dimensional (1D) photoexcited electron-hole plasma. The
leading-order dynamical screening approximation is used in the calculation
by treating electron-electron Coulomb interaction and electron-optical phonon
Fr\"{o}hlich interaction on an equal footing. We calculate the
exchange-correlation induced band gap renormalization (BGR) as a function of
the electron-hole plasma density and the quantum wire width. The calculated BGR
shows good agreement with existing experimental results, and the BGR normalized
by the effective quasi-1D excitonic Rydberg exhibits an approximate
one-parameter universality.Comment: 11 pages, 3 figure
Precision determination of band offsets in strained InGaAs/GaAs quantum wells by C-V-profiling and Schroedinger-Poisson self-consistent simulation
The results of measurements and numerical simulation of charge carrier
distribution and energy states in strained quantum wells In_xGa_{1-x}As/GaAs
(0.06 < x < 0.29) by C-V-profiling are presented. Precise values of conduction
band offsets for these pseudomorphic QWs have been obtained by means of
self-consistent solution of Schroedinger and Poisson equations and following
fitting to experimental data. For the conduction band offsets in strained
In_xGa_{1-x}As/GaAs - QWs the expression DE_C(x) = 0.814x - 0.21x^2 has been
obtained.Comment: 9 pages, 12 figures, RevTeX
Shifted Excitation Raman Difference Spectroscopy Applied to Extraterrestrial Particles Returned from the Asteroid Itokawa
Two extraterrestrial particles from the asteroid Itokawa are investigated applying Shifted Excitation Raman Difference Spectroscopy (SERDS). These particles were returned by the Hayabusa mission of the Japanese Space Agency JAXA. For SERDS a diode laser based microsystem light source at 488 nm is used for excitation. It has been found that fluorescence signals masking the Raman spectral features of interest can be substantially separated by applying SERDS. Therefore, SERDS improves the information obtained from the Raman spectra and enables a reliable analysis for investigations on extraterrestrial samples
Ultrahigh-brightness 850 nm GaAs/AlGaAs photonic crystal laser diodes
This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This article appeared in Appl. Phys. Lett. 93, 221102 (2008) and may be found at https://doi.org/10.1063/1.3040322.One-dimensional photonic crystal lasers emitting in the 850 nm range show high internal quantum efficiencies of 93% and very narrow vertical beam divergence of 7.1° (full width at half maximum). 50m broad area lasers with unpassivated facets exhibit a high total output power of nearly 20 W in pulsed mode with a divergence of 9.5°Ă11.3° leading to a record brightness of 3Ă108Wcmâ2srâ1, being presently the best value ever reported for a single broad area laser diode. 100m broad devices with unpassivated facets show continuous wave operation with an output power of 1.9 W.DFG, 43659573, SFB 787: Halbleiter - Nanophotonik: Materialien, Modelle, Bauelement
Extraordinary carrier multiplication gated by a picosecond electric field pulse
The study of carrier multiplication has become an essential part of many-body physics and materials science as this multiplication directly affects nonlinear transport phenomena, and has a key role in designing efficient solar cells and electroluminescent emitters and highly sensitive photon detectors. Here we show that a 1-MVcmâ1 electric field of a terahertz pulse, unlike a DC bias, can generate a substantial number of electronâhole pairs, forming excitons that emit near-infrared luminescence. The bright luminescence associated with carrier multiplication suggests that carriers coherently driven by a strong electric field can efficiently gain enough kinetic energy to induce a series of impact ionizations that can increase the number of carriers by about three orders of magnitude on the picosecond time scale
EPR, ENDOR, and Special TRIPLE measurements of Pâą+ in wild type and modified reaction centers from Rb. sphaeroides
Compound Semiconductors 1999. Proceedings of the 26th International Symposium on Compound Semiconductors: Berlin, Germany, 22 - 26 August 1999
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