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Researchers investigated the growth of germanium (Ge) on partially gallium-terminated Si(111) substrates. They demonstrated that Ge growth causes redistribution of Ga into condensed and exhausted areas, and that this pattern influences the succeeding growth of Ge. The Ge continues to grow in layer-by-layer mode in the Ga-condensed areas and in Stranski-Krastanov mode in the other areas. The controlling influence is on alignment of Ge clusters rather than size of clusters.

A combined scanning reflection electron microscope/scanning tunneling microscope was employed in analyzing the selective thermal desorption (STD) of electron stimulated SiO2 films less than 1 nm thick. Results show that STD-formed clean Si open windows have uniform linewidth and atomically flat surface morphology. The surface morphology was also found to be dependent on desorption temperature, oxide film thickness and electron dose.

Modifications were made on a conventional transmission electron microscope operating with a cold field emission source to allow differential phase contrast mapping and observations of microscopic magnetic characteristics. Tests have shown that the Lorentz electron microscope is capable of providing information on the details of bits recorded on longitudinal recording media. In addition, it was useful for studying the effect of delineated bit profiles on device performance.

We succeeded in laser-induced magnesium (Mg) production from magnesium oxide (MgO) using Si-based agents, silicon (Si) and silicon monoxide (SiO). In these experiments, a cw CO2 laser irradiated a mixture of Mg and Si-based agents. Both experimental studies and theoretical analysis help not only understand the function of reducing agents but also optimize Mg extraction in laser-induced Mg production. The optimal energy efficiencies 12.1 mg/kJ and 4.5 mg/kJ of Mg production were achieved using Si and SiO, respectively. Besides, the possibility of recycling Si and SiO was preliminarily investigated without reducing agents but only with laser-irradiation. As for the Si-based agents recycling, we succeed in removing 36 mol % of oxygen fraction from SiO2, obtaining 0.7 mg/kJ of Si production efficiency as well as 15.6 mg/kJ of SiO one at the same time. In addition, the laser irradiation to MgO-SiO mixture produced 24 mg/kJ of Si with more than 99% purity. [ABSTRACT FROM AUTHOR]

High density of crystal defects is formed in Si layers during their growth on the nanostructured surface composed of dense arrays of Ge islands grown on oxidized Si substrates. Although these defect-rich Si layers exhibit intense photoluminescence only at low temperatures, the forward-biased diodes with the Si layers located in the region of the p-i-n+ junction can emit light at room temperature. The difference suggests that the influence of thermal emission of carriers from defect states on the light emission intensity is essentially reduced when the spatial distribution of carrier density is governed by the bias voltage and band bending. The results show that Si layers emitting light in the 1.4–1.7 μm range at room temperature can be prepared by means of growth. [ABSTRACT FROM AUTHOR]

Silicon layers grown on oxidized Si surfaces at temperatures between 400 and 500 °C exhibit intense photoluminescence (PL) in the D1 region after annealing at high temperatures (up to 1100 °C). This PL is associated with structural defects that are formed due to the mechanisms of Si growth and thermal relaxation. The growth proceeds through the nucleation of epitaxial and nonepitaxial Si islands. Their coalescence occurs with the formation of a number of interfacial defects, which propagate into the Si layer as it grows. Annealing modifies the structure of the defect and makes them efficient for optical emissions. These Si structures are able to produce PL in the D1 region from thin Si layers at room temperature. [ABSTRACT FROM AUTHOR]

The performance and efficiency of molecularly doped organic light-emitting devices (OLEDs) using voltage pulses have been investigated. The maximum current density and peak luminance have been found to depend on the pulse duration and device size, which was attributed to the heat effect in device. The self-quenching of dye molecules, especially at a high current density of ∼A/cm2, can be effectively inhibited using a low concentration of acceptor in donor system as a light-emitting layer (EML). For an OLED using a 0.4-mol % rubrene in Alq3 as an EML, a maximum peak luminance of 5.66×106 cd/m2 at 52.8 V can be sustained under the voltage pulses of duration of 5 μs. The current efficiency has been observed to decrease rapidly with the current density in device, which was believed to result from the annihilation of excitons. We have also investigated the performance of a pulsed OLED with an emitter layer of 4.0-mol % 1,4-bis[2-[4-[N,N-di(p-tolyl)amino]phenyl]vinyl]benzene in 4,4′-bis(9-carbazolyl)biphenyl, which has been known to exhibit low-amplified spontaneous emission under a pulsed nitrogen laser. [ABSTRACT FROM AUTHOR]

High density of crystal defects is formed in Si layers during their growth on the nanostructured surface, which is composed of dense arrays of Ge islands grown on oxidized Si substrates. The results have shown that Si layers emitting light in the 1.4-1.7 [micro]m range at room temperature is prepared by means of growth.

The performance and efficiency of molecularly doped organic light-emitting devices (OLEDs) using voltage pulses was investigated. The maximum current density and peak luminance was found to depend on the pulse duration and device size, which was attributed to the heat effect in device and the self-quenching of dye molecules, especially at a high current density of ~A/cm(sub 2), can be effectively inhibited using a low concentration of acceptor in donor system as a high-emitting layer.