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Studies on the operation of evaporated ZnS:Mn alternating-current thin-film electroluminescent devices provide evidence for electron-hole pair release by band-to-band impact ionization. Empirical field-clamping behavior, experimental and simulated charge transfer properties, interface distribution and Monte Carlo simulation substantiate the evidence. The holes generated by impact ionization are trapped near the phosphor/insulator interface, as suggested by lack of overshoot in capacitance-voltage and internal charge-phosphor field curves.

Experimental techniques help investigate the electroluminescence of standard and pseudomorphic (PM) InGaAs high-electron-mobility transistors between 0.7 and 1.6 eV at room and cryogenic temperatures. An interaction between the DX centers and hot holes in the AlGaAs barrier accounts for the broad band at 0.8-0.9 eV for PM transistors. A peak arises due to the GaAs substrate, while the InGaAs layer subbands account for the observed doublet in PM transistors.

Electroluminescence associated with ac voltage aging of polyolefins has been reported under divergent field configuration. Neither the mechanism of excitation nor the nature of luminescent centers are well understood in these polymers. Homogeneous field experiments are desirable since they are easier to run and more light can be collected, thereby allowing spectral analysis to be made. We describe a suitable experimental configuration for electroluminescence detection from polyethylene and polypropylene films submitted to a homogeneous field and report on surface roughness, field, and time dependence of the light emission. Field and time dependence of the light spectra are also investigated. It is shown that the light originates from the polymer bulk and is controlled by the surface roughness of the films. The light spectrum appears to consist of two components which exhibit different behavior as a function of field and stressing time. A tentative explanation is given in terms of competition between two different excitation processes.

Characterization of InGaAsP lasers by a near-field scanning optical microscope reveals irregularities and defects in the waveguide. The local and overheating of the laser assessed through shear force and near-field images enable better understanding of inhomogeneities in growth. This technique helps overcome carrier leakage and decrease in threshold current and does not require any particular kind of surrounding. All these facts make this method a favored one.

A newly developed electroluminescent diode consisting of a thin polymer layer and a thick molecular layer emits green, red and blue light simultaneously. The thin polymer layer is the poly(3-(4-octylphenyl)-2,2'-bithiophene) and the thick molecular layer is the 2-(4-biphenyl)-5-(4-tertbutyl-phenyl)1,3,5-oxadiazole. The light emission turn-on voltage is 7 volts. A 0.3% of quantum efficiency is exhibited for light conversion.

Pure poly(N-vinylcarbazole) (PVK) and its blends with a conjugated-nonconjugated multiblock copolymer (CNMBC) exhibit electroluminescence (EL) in a single active layer EL device with the structure of ITO/PVK/Al. The emission peak observed in the EL spectra of the blends of PVK and CNMBC originates from an exciplex produced by the two polymers. A PVK-rich blend produces a single bright emission peak.

Pulse excitation analysis of electroluminescence (EL) gold-coated porous silicon reveals that the EL decreases after 30 minutes of annealing and is independent of all ambients. The EL is completely eliminated above a temperature of 480 degrees Celsius. The EL peak wavelength does not undergo any spectral shift.

Circularly polarized photoluminescence excitation spectroscopy was used to observe the Stark effect in electroluminescence of AlGaAs/GaAs symmetric coupled quantum wells (CDQWs) contained in a p-i-n diode. An external electric field induces the quantum-restricted Stark effect in CDQWs used in several optoelectronic applications.

A sandwich structure that comprises two rough aluminum and indium tin oxide electrodes and a plasma-deposited hydrogenated carbon exhibits electroluminescence. Temperature-dependent emission efficiency and light spectra reveal the presence of surface plasmons during emission. Electroluminescence is a result of radiative decay of surface plasmons.

The negative resistance effect in thin-film electroluminescent devices involves variation of space charge in the phosphor layer. The simulation results of a numerical model are similar with other experimental results. Space charge decreases continuously in time and by recombination with transferred electrons.

Analysis of electrical mechanism of sulfide-based thin film electroluminescence devices reveals the presence of deep donors that transfer electrons to conduction band. Impact ionization and impact excitation are two methods of impurity excitation that produce light emissions. Radiative relaxation channel is studied using deexcitation yields of the films.

Ultraviolet (UV) radiation from an argon ion laser enhanced electroluminescent (EL) emission of a ZnS:Tb thin film near threshold, while weakening EL at higher voltages. These effects of EL emission were related to photogenerated carriers that modify the build up and transport of charge and the electric field.

Light-emitting porous Si that luminesce at room temperature exhibit a degradation of the electroluminescence with time and strong laser heating effects. Light emitting porous Si can be obtained by the anodic etching of p-type Si samples in a HF-ethanol solution, and its properties can be studied using an Auger or Raman spectroscopy. Photoluminescence is more efficient than electroluminescence.

Electroluminescence (EL) is caused by carrier injection through Au/porous silicon Schottky barrier and porous silicon/p-Si heterojunction into corrugated Si nanostructures, where the radiative recombination of carriers take place. The doubly injected short voltage method is used to study EL behavior in Au/porous silicon/silicon/aluminum structure. Quality of Au/porous silicon contact determines the delay time in light emitting diodes.

The analysis of light emission from GaAs metal-semiconductor field effect transistors and its impact on ionization gives information on the mechanisms needed for electroluminescence. The electron-hole pairs, produced by impact ionization in the device, are not dependent on bias conditions. The extra gate current indicates the electrical characteristics of the device in the preavalanche regime.

The electroluminescence observed during the anodic oxidation of porous silicon layers formed on highly P-doped substrates is investigated for determining its different characteristics. The characteristics of the emission are similar to those of photoluminescence found on the same porous layers, and both the phenomena use the same basic mechanisms. The passivation enhancement provided by the electrochemical oxidation explains the increase in emission intensity with oxidation.

Synthesis of a terpyridine ruthenium (II) complex containing a substituted and an unsubstituted terpyridine ligand is done and its luminescence properties are studied in a solid-state single-layer light-emitting electrochemical cell. The obtained devices emitted light of a very deep red colour at low external applied bias.

Room temperature 1.54 mum electro luminescence (EL) was observed from Au/SiO(sub 2):Er/n(super +)-Si and Au/SiO(sub x):Si:Er/n(super +)-Si diodes. A SiO(sub x):Si:Er film deposited on a n(super +)-Si substrate by the magnetron sputtering technique was revealed to be a promising material for efficient Er(super 3+) EL.

The application for full color displays of hybrid organic-inorganic GaN-based light-emitting diodes (LED) was examined. The LED was composed of two parts, namely, the GaN-based eletroluminescent part and the organic thin-film-based fluorescent part whose absorption of electroluminescence enabled fluorescing at a longer wavelength, thereby causing color conversion. Deposition at lower temperatures was also demonstrated to produce organic films with enhanced surface smoothness.

Aromatic compounds such as xylene are used as sources of carbon during deposition to produce amorphous silicon carbide which exhibits strong blue luminescence. The property of the strong blue luminescence is used to develop electroluminescent materials to manufacture flat-screen full-color displays. A combination of silicon carbide lattice with considerable amorphous silicon carbide constitutes the material.

The dependence of the voltage-controlled negative resistance and other characteristics of the Al-[Al.sub.2][O.sub.3]-Au diodes on the temperature is analyzed. The temperature dependent metal-nonmetal transition exhibited by the electroluminescence of the diodes is also discussed.

Equations describing effect of electronic nonuniformities on electroluminescence (EL) and the electron beam induced current (EBOC) images are analyzed on Cu(In,Ga)[Se.sub.2] solar cells. The samples have shown the largest variation in carrier collection function on a length scale of over 100 [micro]m while the band gap has varied almost linearly across the cell and the impact of shunt, series and stack resistances on EL images is discussed.

A blue light emitting diode (LED) is grown on top of a (Ga, In)N/GaN multiple quantum well (QW) acting as a light converter from blue to green-yellow wavelength. A very low blueshift is observed as a function of the injection current, which is explained by the fact that the carrier density per QW in the light converter has stayed relatively low when compared to the case of classical current-injected green LEDs.

Several experimental analyses are conducted to explain the mechanisms involved in the suppression of the roll-off characteristics of electroluminescence efficiency exhibited by the organic light emitting diodes at high current densities. At the current densities above 100 A/[cm.sup.2], the diodes are shown to exhibit the suppression with a balanced bipolar injection and transport.

A method for surface reconstruction of electron injection layers based on conjugated oligoelectrolytes atop an electroluminescent layer in the presence of air is described. The proposed mechanism involves hydration and concomitant increase of the interfacial energy with the underlying hydrophobic surface followed by dewetting via a nucleation process.

The article explains the synthesis and properties of the various ZnO-organic hybrid white light emitting diodes that are grown on flexible plastic via the low temperature aqueous chemical method. The various properties exhibited by these diodes are also studied.

A model is developed for predicting the performances of microscale Cu(In,Ga)[Se.sub.2] (CIGS) solar cells under concentrated sunlight, which is based on the analysis of the impact of the window spread sheet resistance. The model is used for extracting the value of the sheet resistance from simple current-voltage or electroluminescence measurements.

The electroluminescence (EL) characteristics of a set of InAs/GaInNAs quantum dot (QD) light-emitting diodes with varying In and N contents are studied. The studies have shown that the EL thermal quenching has an activation energy that is attributed to carrier escape from the QD to the capping layer.

The analysis of the electroluminescence (EL) intensity distribution has helped in obtaining the current density distribution under a certain current bias and the sheet resistance. Two-dimensional numerical simulation of the current density distribution is used to a GaInP cell and a reciprocity theorem is found for current spreading, which is used for interpreting the EL images.

The effect of rare-earth clustering in dielectric media on the electroluminescence (EL) intensity, the charge trapping and the EL quenching is examined by using Tb and Eu-implanted Si[O.sub.2] layers. It is shown that in the case of Eu-implanted Si[O.sub.2], the quenching of the main EL line of [Eu.sup.3+] is correlated with positive charge trapping in the bulk of the dielectric.

The article presents a new approach, which can be used for the modulated photocarrier radiometric imaging of the various multicrystalline Si solar cells. The methodology is shown to be extremely advantageous, as it exhibits the highest contrast, as well as sensitivity to the defects, hence giving extremely accurate results.

The article presents a complete analysis of the circularly polarized electroluminescence that is exhibited by the various InAs-based spin-light emitting diode structures. The results demonstrate the absence of any relationship between the optical and the spin polarization of such semiconductors.

Several studies are conducted to explain the reverse voltage current characteristics and the electroluminescence of the various 4H-SiC avalanche photodiodes. The excess leakage currents occurring in the diodes with edge or screw dislocations are also analyzed.

The delayed electroluminescence approach is employed to explain the triplet-triplet annihilation zone and annihilation systems. The application of the methodology for the detection of triplet exciton diffusion length is also analyzed.

An abnormal current amplification phenomenon appearing in high-quality chemical-vapor-deposited (CVD) diamond under high electric fields is examined by measuring current-voltage and electroluminescence (EL) characteristics of an asymmetric graphite-intrinsic-diamond-graphite (G-ID-G) structure specially prepared with a high-quality homoepitaxial CVD diamond layer. The field calculations using a finite element method has shown both injections from the G layer to the ID layer and high-field-induced excitations of valence electrons in the ID layer to the conduction bands by the impact of the current.

A self-consistent calculation is used for examining the feasibility of electroluminescent refrigeration and light emitting without heat generation in AlGaAs/GaAs heterstructures by considering the effects of various recombination processes. The studies have shown that a net cooling power and a high-power light emitting without heating are feasible and they need an overall efficiency of more than 90% that is achieved if the photon recycling efficiency is high.

The main energy loss mechanism is studied in electroluminescent (EL) processes in phosphor-sensitized fluorescent polymer light-emitting devices. The energy transfer from phosphorescent triplet state to the fluorescent triplet state has great negative impact on the phosphor-sensitized fluorescent process.

Several electroluminescence and photoluminescence measurements are conducted to analyze the reduced radiative recombination taking place in the low-well-number strain-balanced quantum well solar cells. The mechanisms leading to the reduction of the quasi-Fermi level separation (QFLS) in the devices are also discussed.

The synthesis, as well as the charging effects observed on the electroluminescence (EL) performance of the various nc-Si/a-Si[O.sub.2] films are discussed. The charging up of the trapping centers of the films is shown to lead to a significant decrease in the EL intensity.

Systematic evolution of the electroluminescence (EL) with increasing flash lamp annealing (FLA) temperature in an Er-doped Ge-rich metal-oxide semiconductor structure is described. The enhancement of the EL decay time with rising FLA temperature is associated with recrystallization of the damaged Ge clusters in the absence of Ge outdiffusion.

Near-infrared electroluminescence and optical amplification in semiconductor thin films based on a nonconjugated polymer doped with luminescent and electron-transport molecules are studied. The results have helped in the development of near-infrared polymer lasers and optical amplifiers.

Highly efficient white and nonwhite hybrid organic light-emitting diodes (OLEDs) in which singlet and triplet excited states are generated in the recombination zone for use in fluorescence and phosphorescence, respectively are demonstrated. The spectral analysis, time-resolved electroluminescence, magnetic field effect, and electron paramagnetic resonance verified the triplet-harvesting mechanism and material properties in all OLED devices.