• Proceedings of the KIEE Conference
• /
• 2005.11a
• /
• pp.81-83
• /
• 2005

Photocurrent of a single-crystalline Si nanowire is investigated in this paper. Single-crystalline Si nanowires with amorphous $SiO_2$ shells were first synthesized from ball-milled SiO powders by thermal chemical vapor deposition, and then the amorphous $SiO_2$ shellswere etched out from the as-synthesized Si nanowires. For a single-crystalline Si nanowire, photocurrent-voltage curves taken in air at room temperature were non-linear, and rapid photoresponses were observed when the light was switched on and off. The photocurrent was not changed in intensity under the illumination. Photocurrent mechanism in the single-crystalline Si nanowire is discussed in this paper.

• Journal of the Korean institute of surface engineering
• /
• v.44 no.3
• /
• pp.89-94
• /
• 2011

In this study, the photocurrent characteristics of plasma sprayed $TiO_2$ coatings have been investigated according to additive transition metal (Fe, Mn, Nb powder) and heat treatment conditions. The plasma sprayed $TiO_2$ coatings by heat treatment at $400^{\circ}C$ and 90 min had the higher photocurrent at ultraviolet light, no photocurrent at visible light. The photocurrent of plasma sprayed $TiO_2$ coatings added by Fe, Mn, Nb (named by plasma sprayed $TiO_2$ composite coatings) was lower than that of plasma sprayed $TiO_2$ coatings at ultraviolet light, as was low in intensity ratio of XRD(101)/(110). and the atomic percentage of oxygen by plasma sprayed $TiO_2$ composite coatings was higher than that by plasma sprayed $TiO_2$ coatings. The photocurrent of plasma sprayed $TiO_2$ composite coatings in heat treatment at $400^{\circ}C$ and 90 min was higher than that of plasma sprayed $TiO_2$ coatings in same heat treatment conditions at ultraviolet and visible light, as was high in oxygen affinity by heat treatment.

• Journal of Photoscience
• /
• v.10 no.2
• /
• pp.199-202
• /
• 2003

The relationship between the morphology of nanostructured TiO$_2$ films and the photo-injected electron transport has been investigated using intensity-modulated photocurrent spectroscopy (IMPS). For this purpose, three different TiO$_2$ films with 5 ${\mu}{\textrm}{m}$ thickness are prepared: The rutile TiO$_2$ film with 500 nm-sized cluster-like spherical bundles composed of the individual needles (Tl), the rutile TiO$_2$ film made up of non-oriented, homogeneously distributed rod-shaped particles having a dimension of approximately 20${\times}$80 nm (T2), and the anatase TiO$_2$ film with 20 nm-sized spherically shaped particles (T3). Cross sectional scanning electron micrographs show that all of the TiO$_2$films have a quite different particle packing density: poorly packed Tl film, loosely packed T2 film and densely packed T3 film. The electron transport is found to be significantly influenced by film morphology. The effective electron diffusion coefficient D$_{eff}$ derived from the IMPS time constant is an order of magnitude lower for T2 than for T3, but the D$_{eff}$ for the Tl sample is much lower than T2. These differences in the rate of electron transport are ascribed to differences in the extent of interparticle connectivity associated with the particle packing density.ity.

• Journal of Electrical Engineering and Technology
• /
• v.7 no.6
• /
• pp.965-970
• /
• 2012

Structure and optical properties of cadmium sulphide-zinc oxide composite nanorods have been evaluated by suitable characterization techniques. The X-ray diffraction spectrum contains a series of peaks corresponding to reflections from various sets of lattice planes of hexagonal ZnO as well as CdS. The above observation is supported by the Micro-Raman spectroscopy result. The optical reflectance spectra of CdS-ZnO is compared with that of ZnO where we observe an enhanced absorption and hence diminished reflection from CdS-ZnO compared to that from only ZnO. A very small intensity of the visible photoluminescence peak observed at 550 nm proves that the ZnO nanorods have very low concentrations of point defects such as oxygen vacancies and zinc interstitials. The photocurrent in the visible region has been significantly enhanced due to deposition of CdS on the surface of the ZnO nanorods. CdS acts as a visible sensitizer because of its lower band gap compared to ZnO.

• Applied Chemistry for Engineering
• /
• v.22 no.5
• /
• pp.461-466
• /
• 2011

In this study, the fluorine doped $TiO_2$ was prepared as a photoelectrode in order to improve the efficiency of dye-sensitized solar cells and estimated the electrochemical characterizations. The energy conversion efficiency of the prepared dye-sensitized solar cells using fluorine doped $TiO_2$ was calculated from a current-voltage curve. The efficiency of prepared dye-sensitized solar cells was improved by about maximum three times by F-doping on $TiO_2$. It was suggested that the efficiency of dye-sensitized solar cells was improved by hybrid semiconductors of $TiO_2/TiOF_2$ in photoelectrode based on reduced $TiOF_2$ energy level via fluorine doping. It can be confirmed that the electron transport was faster but the electron recombination was slower by doping fluorine on $TiO_2$ in photoelectrode through intensity-modulated photocurrent spectroscopy and intensity-modulated photovoltage spectroscopy analysis.

• 전기의세계
• /
• v.17 no.2
• /
• pp.16-26
• /
• 1968

Cds is possible to add excess donors and to compensate partially using other group metals as acceptors. The impurities can ble incorporated either during crysta growth or by diffusion into a bulkcrystal. The addition of rimpurities leads also to the production of vacancies in a manner depending on the atmosphere surrounding the crystal during growth, during the diffusion process or using bulk. Cds of the mentioned above affects spectral sensitivity, speed of response, the variation on photocurrent, electron life time, and decay of photoconductivity with temperature and with intensity of illumination. In the work to be deseribed, these properties have been studied between liquid nitrogen and room temperature. In addition, the electron trap distribution has been correlated with speed of response, variation of photocurrent with temperature in various atmosphere. Four major trapping levels have been observed, and their identification with impurity and vacancy levels is discussed. And also the effects of lattice imperfections on the photoconductive properties CdS were investigated in detail.

• Transactions on Electrical and Electronic Materials
• /
• v.14 no.1
• /
• pp.16-19
• /
• 2013

Frequency filters with various filtering wavelengths were used in the photoelectric characterization of hydrogenated amorphous silicon thin film transistor (a-Si:H TFT) and the experimental results were described and analyzed in terms of the photon energy spectral characteristics calculated from the integration of the photon energy and the spectral intensity of transmitted backlight through the filters at each wavelength. From the comparison of the photocurrents and the calculated photon energy spectrums for the filtered ranges of wavelength, it was possible to conclude that the photocurrents are closely related to the photon energy spectrums of the backlight.

• Journal of the Korean Institute of Telematics and Electronics
• /
• v.25 no.9
• /
• pp.1068-1073
• /
• 1988

PIN-Photodiodes were fabricated with CO2 laser annealed SOI and their electric characteristics were measured. Dark current decreased and photocurrent-dark current ratio increased as the grain size of polycrystalline silicon in intrinsic region increased. In case of the largest grain, 10-20um, dark current was 30 n A (at - 4V) and photocurrent was proportional to light intensity.

• Journal of the Korean Applied Science and Technology
• /
• v.18 no.1
• /
• pp.49-54
• /
• 2001

Ultra-thin films of organic charge transfer complex were prepared on a hydrophilic substrate by Langmuir-Blodgett(LB) technique. In this study, the photoelectric properties of a LB film consisting of (N-docosyl quinolinium)-TCNQ(1:2) complex was investigated. The visible light(${\lambda}$ : 700 nm) of xenon lamp was illuminated on the LB films and light absorptivity and photoconductivity were observed. The photocurrent increased linearly and was saturated at the light intensity of 23 ${\mu}W/cm^{2}$.

• Journal of Sensor Science and Technology
• /
• v.18 no.1
• /
• pp.48-53
• /
• 2009

$Eu^{2+}$-doped ${SrAl_2}{O_4}$ and $Eu^{2+}$, $Dy^{3+}$ co-doped ${SrAl_2}{O_4}$ phosphors have been synthesized by conventional solid state method. Photocurrent properties of $Eu^{2+}$ doped ${SrAl_2}{O_4}$ and $Eu^{2+}$, $Dy^{3+}$ co-doped ${SrAl_2}{O_4}$ phosphors, in order to elucidate $Dy^{3+}$ co-doping effect, during and after ceasing ultraviolet-ray (UV) irradiation have been investigated. The photocurrent of $Eu^{2+}$, $Dy^{3+}$ co-doped ${SrAl_2}{O_4}$ phosphors during UV irradiation was 4-times lower than that of $Eu^{2+}$-doped ${SrAl_2}{O_4}$ during UV irradiation, and 7-times higher than that of $Eu^{2+}$-doped ${SrAl_2}{O_4}$ after ceasing UV irradiation. The photocurrent results indicated that holes of charge carriers captured in hole trapping center during the UV irradiation and liberated after-glow process, and made clear that $Dy^{3+}$ of co-dopant acted as a hole trap. The photocurrent of ${SrAl_2}{O_4}$ showed a good proportional relationship to UV intensity in the range of $1{\sim}5mW/cm^2$, and $Eu^{2+}$-doped ${SrAl_2}{O_4}$ was confirmed to be a possible UV sensor.