Search

The authors demonstrate a potential application of quantum dots for the detection of photons, showing that the Coulomb interaction resulting from the capture of photoexcited carriers by quantum dots produces a detectable change in the source-drain resistance of the transistor. This quantum effect is more pronounced with higher illumination, displaying staircase quantum steps with ΔV=4 mV on the I-V characteristics at room temperature, implying that the photocurrent is increased as the light intensity is increased. The responsitivity of device is R∼3.98×106 A/W for Vd=0.18 V, and external quantum efficiency is more than 8.6%. [ABSTRACT FROM AUTHOR]

The authors report here the enhanced luminescence properties of SrSi2O2N2 doped with Eu and M (M=Ce, Dy, and Mn). The Eu and Eu, Mn-codoped powders were prepared by a solid state reaction at temperatures between 1400 and 1600 °C under H2 (25%)–N2 (75%) atmosphere. The Eu, M-codoped Sr1-x-ySi2N2O2 phosphors have the monoclinic structure with lattice parameters a∼15.6 Å, b∼16.2 Å, c∼9.4 Å, and β∼91°. The phosphors can be efficiently excited in the UV to visible region, making them attractive as conversion phosphors for a light emitting diode application. A green-yellow emission was observed for Eu,M-codoped Sr1-x-ySi2N2O2. The addition of M in the Eu site in SrSi2O2N2 remarkably enhances the luminescent intensity by the factor of 144%, 148%, and 168% for Ce, Dy, and Mn, respectively. [ABSTRACT FROM AUTHOR]

A novel blue phosphor based on phosphate host matrix, KSrPO4 doped with Eu2+, was prepared by solid state reaction. The phosphor invariably emits blue luminescence with a peak wavelength at 424 nm under ultraviolet excitation at 360 nm. Eu2+-doped KSrPO4 phosphors show higher thermally stable luminescence which was found to be better than commercially available Y3Al5O12:Ce3+ phosphor at temperature higher than 225 °C. [ABSTRACT FROM AUTHOR]

A three-band white light-emitting diode (LED) was fabricated using an InGaN-based blue LED chip that emits 455 nm blue light, and green phosphor SrSi2O2N2:Eu and red phosphor CaSiN2:Ce that emit 538 nm green and 642 nm red emissions, respectively, when excited by the 455 nm blue light. The luminous efficacy of this white LED is about 30 lm/W at a dc of 20 mA. With increasing dc from 5.0 to 60 mA, both the coordinates x and y of the white LED tend to be the same, and consequently the Tc is the same and the Ra increases to 92.2. [ABSTRACT FROM AUTHOR]

In this letter, we shall describe a method, utilizing the proximity effect in electron beam lithography, suitable for fabricating silicon dots and devices, and demonstrate the electronic characteristics of the Si single-electron transistor. The drain current (Id) of the device oscillates against gate voltage. The electrical characteristics of the single-electron transistor were observed to be consistent with the expected behavior of electron transport through gated quantum dots, at up to 150 K. The dependence of the electrical characteristics on the dot size reveals that the Id oscillation follows from the Coulomb blockade by poly-Si grains in the poly-Si dot. The method of fabrication of this device is completely compatible with complementary metal–oxide–semiconductor technology, raising the possibility of manufacturing large-scale integrated nanoelectronic systems. [ABSTRACT FROM AUTHOR]