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Conduction electron spins interacting with magnetic impurity spins can lead to an indirect exchange interaction between magnetic impurities in nonmagnetic metals or semiconductors, namely, RKKY interaction. In general, this RKKY coupling is too weak to apply on devices. In this paper, we find that when a laser field of appropriate frequency irradiates the nanosystems, it can greatly strengthen the RKKY interaction. This is the so-called optical resonant RKKY interaction. We give the resonant frequencies for different size samples, and calculate the exchange integrals for these samples on the near- resonant conditions. This optical resonant RKKY coupling may be strong enough to guarantee its application on spintronic devices. PACS Nos.: 75.30.Hx, 75.78.Jp, 75.30.Et, 72.25.Rb, 78.67.Uh. L'interaction des spins des electrons de conduction avec les spins d'impuretes magnetiques peut mener a une interaction d'echange indirect entre les impuretes magnetiques dans des metaux non magnetiques ou des semi-conducteurs, nommement l'interaction RKKY. En general, cette interaction RKKY est trop faible pour avoir des applications dans des dispositifs. Nous trouvons ici que l'illumination laser du nano-systeme a une frequence appropriee peut fortement augmenter l'interaction RKKY. Cet effet s'appelle l'interaction RKKY en resonance optique. Nous donnons ici les frequences de resonance pour differentes grosseurs d'echantillon et calculons les integrales d'echange pour ces echantillons en situation pres de la resonance. Ce couplage de RKKY en resonance optique peut etre assez fort pour permettre son utilisation dans les dispositifs de spintronique. [Traduit par la Redaction], 1. Introduction Conduction electron spins interacting with the magnetic impurity spins can mediate an indirect exchange interaction between two localized impurity spins in bulk metals [1-14] and bulk semiconductors [15-19], [...]

As a kind of Na-incorporating control method, NaF co-evaporation or soda-lime glass thin films (SLGTFs) are useful to improve the photovoltaic performance of Cu(In, Ga)[Se.sub.2] (CIGS) cells fabricated on low-Na substrates. X-ray diffraction (XRD) patterns and scanning electron microscope pictures demonstrate that the grain size of CIGS thin film is reduced with the addition of Na. In addition, a variance of the preferred orientation is found by XRD patterns in terms of SLGTF samples. By a use of 100 nm thick SLGTF as a Na source, the best CIGS solar cell with an efficiency of 13.42% has been obtained. [c] 2010 Optical Society of America OCIS codes: 160.6000, 310.6845.

Owing to their unique optical properties, quantum dots (QDs) with different colors have been applied for simultaneous detection of multiple analytes. However, the use of single QD for multiplex detection of analytes with single-molecule detection has not been explored. Here we report a single QD-based nanosensor for multiplex detection of HIV-1 and HIV-2 at single-molecule level in a homogeneous format. In this single QD-based nanosensor, the QD functions not only as a fluorescence pair for coincidence detection and as a fluorescence-resonance-energy-transfer (FRET) donor for FRET detection but also as a local nanoconcentrator which significantly amplifies the coincidence-related fluorescence signals and the FRET signals. This single-QD-based nanosensor takes advantage of a simple 'mix and detection' assay with extremely low sample consumption, high sensitivity, and short analysis time and has the potential to be applied for rapid point-of-care testing, gene expression studies, high-throughput screening, and clinical diagnostics. 10.1021/ac9026675

We have obtained a simple numerical model that explains the temperature behavior of multi-quantum-dot (QD) nanophotonic devices whose operations are based on optical near-field (ONF) interactions between any two resonant QDs that are in thermal equilibrium. This model involves a set of coupled rate equations that govern the temporal behavior of the QDs' energy level occupancies. Under a certain operating condition, this simple model can substitute for the more complex density matrix (DM) approach in modeling the temperature dependence of the ONF energy transfer rate ([R.sub.ONF]) between any two resonant QDs in thermal equilibrium. The same applies for modeling the system state-filling time ([[tau].sub.S]). Applying our simple model to a two-QD system, we have derived analytical formulas for the interdot and the intradot transfer rates at finite temperatures (T [greater than or equal to] 0). Furthermore, by assuming a unidirectional energy transport operating condition, we have also derived an analytic formula for calculating [[tau].sub.S] for a two-QD system. To the best of our knowledge, this work is the first instance of reporting such analytic equations. Approximated values of [[tau].sub.S] obtained from our simple analytic equation are in reasonable agreements with those calculated by the DM approach. [c] 2010 Optical Society of America OCIS codes: 350.4238, 230.5590.

A systematic study is conducted to modulate the photoresponse of quantum dot solar cells by varying the size and shape of semiconductor nanostructures. The results have highlighted the ability to tune the photoelectrochemical response and photoconversion efficiency via size control of CdSe quantum dots and improvement in the photoconversion efficiency by facilitating the charge transport through Ti[O.sub.2] nanotube architecture.

Total reflection X-ray fluorescence (TXRF) analysis is a well-established method to monitor lowest level contamination on semiconductor surfaces. Even light elements on a wafer surface can be excited effectively when using high-flux synchrotron radiation in the soft X-ray range. To meet current industrial requirements in nondestructive semiconductor analysis, the Physikalisch-Technische Bundesanstalt (PTB) operates dedicated instrumentation for analyzing light element contamination on wafer pieces as well as on 200- and 300-mm silicon wafer surfaces. This instrummentation is also suited for grazing incidence X-ray fluorescence analysis and conventional energy-dispersive X-ray fluorescence analysis of buried and surface nanolayered structures, respectively. The most prominent features are a high-vacuum load-lock combined with an equipment front end module and a UHV irradiation chamber with an electrostatic chuck mounted on an eight-axis manipulator. Here, the entire surface of a 200or a 300-mm wafer can be scanned by monochromatized radiation provided by the plane grating monochromator beamline for undulator radiation in the PTB laboratory at the electron storage ring BESSY II. This beamline provides high spectral purity and high photon flux in the range of 0.078-1.86 keV. In addition, absolutely calibrated photodiodes and Si(Li) detectors are used to monitor the exciting radiant power respectively the fluorescence radiation. Furthermore, the footprint of the excitation radiation at the wafer surface is well-known due to beam profile recordings by a CCD during special operation conditions at BESSY II that allow for drastically reduced electron beam currents. Thus, all the requirements of completely reference-free quantitation of TXRF analysis are fulfilled and are to be presented in the present work. The perspectives to arrange for reference-free quantitation using X-ray tube-based, table-top TXRF analysis are also addressed.

A numerical and analytical solution is described for the operation of linear optical amplifier. The maximum gain is seen at the cavity mode position.

The influence of lateral fluctuations of the fundamental band gap on the macroscopic light absorptance and emission spectra of spatially inhomogeneous semiconductors is examined. The studies have shown alloy disorder as one possible source of band gap inhomogeneities and the length scale of the fluctuations is smaller than the minority carrier diffusion length.

The theory of control of a set of dots spins through cavity quantum electrodynamics and the quantum basis for the control of decoherence of the electron spin interacting with the nuclei in the quantum dot are elucidated. The case for control of electron spin is used to restore the coherence lost due to the interaction with the nuclear spins in the dot as the mesoscopic shield from the larger environment.

The addition of spectral filtering has shown that entangled photon pairs are emitted from a biexciton decay cascade of a single quantum dots. The density matrix of the polarization state of the photon pair emitted from a continuously pumped quantum dot has satisfied the Peres criterion for entanglement.

The electronic and optical properties of germanium-rich Si/SiGe quantum wells grown on [Si.sub.0.5][Ge.sub.0.5] substrates are examined by a nearest neighbor tight-binding Hamiltonian. The results for group IV conduction intersubband transitions might help in the project of devices for terahertz applications.

A simple quasithermodynamic model is described for the observed anomalies in the temperature dependence of the photoluminescence (PL) spectra of self-assembled quantum dots. The model is extended to quantum dots ensembles with both unimodal and bimodal size distributions.

The photoluminescence yield of undoped semiconductors strongly depending on the excitation power and the intensity distribution is discussed. A simple cylindrical model based on nonlinear recombination and ambipolar carrier diffusion serving to simulate the photoluminescence yield is presented.

A numerical model is described for the calculation of the opto-electronic properties of a semiconductor InAs-InAlGaAs quantum dash active material including the presence of wetting layer (WL) and the quantum mechanical coupling among dashes. The results reveal that WL plays a role in limiting the gain performance such as the maximum gain, the differential gain and the optical gain bandwidth.

The time evolution of gallium nitride quantum dots luminescence is recorded in situ in a scanning electron microscope and electrons of 10keV are injected in a scanning electron microscope during 30 min. All the results are coherently interpreted by an enhanced diffusion of nonradiative effects promoted by nonradiative recombinations.

Single crystals of many semiconductors are grown and the dependence of their physical properties on isotopic composition is investigated. The most conspicuous effects observed deal with the dependence of phonon frequencies and linewidths on isotopic composition.

A set of simple equations that can be used to predict the separation between the primary and secondary Laue spots as a function of sample dimensions, beam position on the sample, and incident-beam energy assuming a pseudoparallel incident beam is presented. These equations can be used to identify the peaks from the back-surface of the sample.

Room temperature photoluminescence (PL) measurements of IV-VI semiconductor multiple quantum well (MQW) structures using diode laser optical pumping at two different excitation wavelengths, 2.5 and 0.91mumicrometer, are described. Active region temperatures during continuous-wave optical pumping were determined from blueshifts in PL emission energies.

The optical absorption of GaAs nanorings under dc and ac electric fields with frequency at the tetrahertz range applied in the plane containing the nanoring is investigated. The applied lateral electric fields change the optical absorption spectra prominently and in the presence of tetrahertz electric fields, the optical spectra may be very different for diferent frequencies.

Two representative methods, namely free carrier absorption and laser deflection measurements, are theoretically investigated. A consistent evaluation rule for extracting carrier and temperature gradients from the detector signals of deflection measurements is derived.

Developing materials with a large optical nonlinearity is important for many device applications such as optical limiters/filters, switches, communications, optical data storage, and biophotonics. The optical nonlinearity depends on the semiconductor, the dot size, and the dot-to-dot spacing.

Research describes the syntheses and photophysical characterization of four Ru(sup)II-polypyridyl compounds containing tripodal ligands. Data indicate that the Ru centers are between 15-17 angstroms from the surface and are attached via an incompletely conjugated bridge, which facilitates unchanged redox and steady-state optical properties upon attachment of nanoparticles.

Broadband low-loss semiconductor satuable absorber mirrors (SESAM) in the 1.55 micrometer wavelength range have been monolithically grown by solid-source molecular-beam epitaxy using a Burstein-Moss blue-shifted distributed Bragg reflector. Reliable operation is demonstrated, without pulse break-up, with pulse energy of over 250 pJ.

The steady state nonlinear optical absorption in small semiconductor quantum dots is studied. However, results show that the larger gains are seen in bigger quantum dots.

Efficient control of millimeter-waves in a slot line on an Si and GaAs substrate is discussed both theoretically and experimentally. The spectral-domain method is used to estimate the propagation and the attenuation constants in the slot line with the density of the optically induced plasma as a parameter. Experiments in the millimeter-wave range of 35-50 GHz are carried out using high-resistivity Si and GaAs wafers with the dimension of 15 mm x 30 mm x 600 [mu]m. The slot-width could be varied from 0.5 to 2 mm. The attenuation of millimeter waves by over 20 dB can be controlled by optical means using light-emitting diodes with 870-nm wavelength and 68-mW optical power. The experimental results agree considerably well with the theory. The response of millimeter waves with pulsed optical illumination is also examined using a high-power laser diode of 20-W optical power and a pulsewidth less than 100 ns. High-speed response due to optically induced plasma is confirmed for the slot line on GaAs substrate. Index Terms--GaAs, millimeter waves, optical control, Si, slot line, solid-state plasma.

Studies of electrical conductivities of ZnS(sub 0.05)Se(sub 0.95) films deposited on quartz substrates indicated that the low temperature conductivity could be explained by hopping of the charge carriers in the Coulomb gap while at elevated room temperature Mott hopping is the predominant mode of conductance in these films which is a distinct cross over from Efros-Shklovoskii hopping. It was observed that the absorption behavior of these films could not be explained from level to level transitions due to size quantization only and significant contributions from inhomogeneity and phonon broadening effects along with optical losses due to scattering must be considered to explain the observed absorption behavior.

It is reported that conducting polymers opened the way to progress in understanding the fundamental chemistry and physics of pi-bonded macromolecules. A new generation of polymers is founded that exhibit the electrical and optical properties of metals or semiconductors and that retain the attractive mechanical properties and processing advantages of polymers.

Research into the photoluminescence excitation (PLE) spectra of CuInS2 crystals produced by the travelling heater technique and the iodine vapor transport technique is presented. The travelling heater samples showed many peaks and dips in their PLE spectra near the band edge. Iodine vapor transport crystals showed only free exciton peaks.

A new study compares the results of small-angle x-ray scattering and Raman scattering measurements of nanocrystals in semiconductor doped silicate glasses.

A new study uses positron annihilation, photoluminescence and x-ray diffraction to study the defects and strain relaxation in GaAs/InxGa1-xAs/GaAs heterostructures, where x= 0.05 to 0.3.

It has been established that photoluminescence from CdSe substrates can be reversibly modulated by adsorption of adenine, guanine, thymine and cytosine and their complementary base pairs. In dimethyl sulfoxide, especially, the CdSe surface seems to encourage the formation of complementary base pairs .

Results are presented of an analysis of nanoscale compositional fluctuations in InGaAs/GaAs quantum wires.

Research was conducted to examine the CuInSe2 (CIS) epitaxial layers on a GaAs substrate (001) grown by molecular beam epitaxy via piezoelectric photoacoustic (PPA) spectroscopy between liquid helium and room temperatures for the dependence of the optical characterization in the CIS samples on the Cu/In ratios. Results indicate that the PPA measurements were effective in analyzing the defect levels and the band gap energy in the CIS/GaAs thin films.

The effect of rapid thermal annealing on bulk GaInp and GaInP/AlGaInP quantum wells grown by solid source molecular beam epitaxy is investigated using deep level transient spectroscopy and time resolved photoluminescence. After the rapid thermal annealing, decreases in the concentration of several deep level traps became apparent. Results also suggest that the defect labeled N3, 0.83 eV, below the conduction band, is the dominant recombination center.

Photoluminescence is used to analyze the optical properties of AlGaN/GaN quantum wells (QW) grown by molecular beam epitaxy (MBE) on sapphire. MBE of group-III nitrides is found to be appropriate for growing such quantum structures due to the well-resolved QW luminescence peaks and the possibility of controlling the Al composition and well thickness exhibited by the photoluminescence spectra.

Research was conducted to synthesize nanocrystalline europium doped yttria using a chemical vapor method. X-ray diffraction, transmission electron microscopy and ultraviolet spectroscopy were used to characterize the powder. Results demonstrate for the first time the possibility of obtaining single phase Y2O3:Eu nanoparticles crystallized in the cubic structure with an average particle size of only 10 nm.

Research was conducted to demonstrate high accuracy measurements of gain, loss and transparency energy in long-wavelength semiconductors based on a hybrid approach using the fundamental relationship between the gain and the spontaneous emission spectra. The approaches alleviates several problems related to the poor signal to noise ratio in the amplified spontaneous emission (ASE) near and below the band edge. Results validate the high reliability of he correlated gain and spontaneous emission spectra.

Algorithms of deducing the refractive index of h-GaN from the optical spectra of heteroepitaxial films were critically analyzed. A one-layer model applied in most works was observed to be insufficient for real nitride films which conventionally are grown using a low temperature buffer layer or/and possess a nonabrupt substrate/film interface and surface defects. A method to characterize nitride layered structures using reflectivity studies over a wide spectral region is presented.

Research was conducted to examine the optical and structural properties of strained InAlAs/InAs(sub x)P(sub 1-x) heterostructures grown by solid source molecular beam epitaxy. X-ray diffraction and photoluminescence measurements were used to analyze the incorporation of As4 into strained InAsP. Results reveal that the photoluminescence properties of the InAlAs/InAsP multiquantum wells were highly dependent on growth conditions.

Research was conducted to measure and model the transition energies and linewidths of various InAlGaAs/AlGaAs quantum wells grown on GaAs substrate. It was possible to make a calibration of the In growth rate and the chemical energies of the In segregation using two reference samples with InGaAs/GaAs quantum wells grown under the same conditions. Results are inn agreement with the broadening expected from random alloy fluctuations and well width fluctuations with an effective interface roughness of 1.1 ML.