Persistent photoconductivity in highly porous ZnO films

2007 ◽  
Vol 101 (1) ◽  
pp. 013709 ◽  
Author(s):  
Jens Reemts ◽  
Achim Kittel
Keyword(s):  
Zno Films ◽  
Persistent Photoconductivity ◽  
Highly Porous

Ultra-rapid synthesis of highly porous and robust hierarchical ZnO films for dye sensitized solar cells

Solar Energy ◽  
2016 ◽  
Vol 136 ◽  
pp. 553-559 ◽  
Author(s):  
Antonio Tricoli ◽  
Noushin Nasiri ◽  
Hongjun Chen ◽  
Anna S. Wallerand ◽  
Marco Righettoni
Keyword(s):  
Solar Cells ◽  
Dye Sensitized Solar Cells ◽  
Zno Films ◽  
Rapid Synthesis ◽  
Dye Sensitized ◽  
Sensitized Solar Cells ◽  
Highly Porous

Effect of annealing and hydrogen plasma treatment on the luminescence and persistent photoconductivity of polycrystalline ZnO films

2017 ◽  
Vol 121 (24) ◽  
pp. 245303 ◽  
Author(s):  
Kh. A. Abdullin ◽  
G. Cicero ◽  
L. V. Gritsenko ◽  
S. E. Kumekov ◽  
A. A. Markhabaeva
Keyword(s):  
Plasma Treatment ◽  
Hydrogen Plasma ◽  
Zno Films ◽  
Persistent Photoconductivity

SYNTHESIS AND PHOTOSENSITIVE PERFORMANCE OF NANOSTRUCTURED ZnO/DYE HYBRID FILM FOR ENERGY CONVERSION

2013 ◽  
Vol 22 ◽  
pp. 18-23
Author(s):  
MAMTA RANI ◽  
S. K. TRIPATHI
Keyword(s):  
Hybrid Film ◽  
Collection Efficiency ◽  
Uv Spectroscopy ◽  
Dye Sensitized Solar Cells ◽  
Decisive Role ◽  
Zno Films ◽  
Zno Film ◽  
Structure Directing Agent ◽  
Doctor Blade ◽  
Highly Porous

The ZnO film prepared by doctor blade method are highly porous in presence of structure directing agent PEG and then can be easily sensitized by various molecules. In the present work, the nanostructured ZnO /dye hybrid film prepared by doctor blade method has been investigated in conductivity and photoconductivity measurements in view of applications in dye-sensitized solar cells (DSSC) and in optoelectronics, since electron transport in these devices plays a decisive role for the electron collection efficiency and therefore for the overall efficiency. The absorption of ZnO film sensitized by Rose Bengal dye (RB) has been studied by UV spectroscopy which indicates that after the dye is adsorbed on the ZnO electrode, its absorption spectra showed red-shift in the peak position compared to the absorbance spectra of dye in ethanol. Highly porous ZnO films are found to have high dark conductivity, probably because of a higher n-doping, which is due to higher concentration of Zn atoms in the film. On the other hand, ZnO /RB hybrid film is found to show a much higher sensitivity to illumination with visible light in photoconductivity measurements due to a higher absolute photoconductivity and lower conductivity in the dark.

Use of fractals to describe microstructures of porous thick-film platinum electrodes

1992 ◽  
Vol 50 (1) ◽  
pp. 314-315
Author(s):  
Steven D. Toteda
Keyword(s):  
Fractal Dimension ◽  
Power Plants ◽  
Electrical Response ◽  
Cubic Phase ◽  
Platinum Electrodes ◽  
Fine Grained ◽  
Impedance Response ◽  
Platinum Particles ◽  
Energy Surfaces ◽  
Highly Porous

Zirconia oxygen sensors, in such applications as power plants and automobiles, generally utilize platinum electrodes for the catalytic reaction of dissociating O2 at the surface. The microstructure of the platinum electrode defines the resulting electrical response. The electrode must be porous enough to allow the oxygen to reach the zirconia surface while still remaining electrically continuous. At low sintering temperatures, the platinum is highly porous and fine grained. The platinum particles sinter together as the firing temperatures are increased. As the sintering temperatures are raised even further, the surface of the platinum begins to facet with lower energy surfaces. These microstructural changes can be seen in Figures 1 and 2, but the goal of the work is to characterize the microstructure by its fractal dimension and then relate the fractal dimension to the electrical response. The sensors were fabricated from zirconia powder stabilized in the cubic phase with 8 mol% percent yttria. Each substrate was sintered for 14 hours at 1200°C. The resulting zirconia pellets, 13mm in diameter and 2mm in thickness, were roughly 97 to 98 percent of theoretical density. The Engelhard #6082 platinum paste was applied to the zirconia disks after they were mechanically polished ( diamond). The electrodes were then sintered at temperatures ranging from 600°C to 1000°C. Each sensor was tested to determine the impedance response from 1Hz to 5,000Hz. These frequencies correspond to the electrode at the test temperature of 600°C.

Microstructural observations of the “Wustite-Spinel” coexistence following quenching of cation-excess spinels, Ni2(1+x)Ti1-xO4

1990 ◽  
Vol 48 (4) ◽  
pp. 1058-1059
Author(s):  
Ian M. Anderson ◽  
Arnulf Muan ◽  
C. Barry Carter
Keyword(s):  
Film Growth ◽  
Spinel Phase ◽  
Model Systems ◽  
Ion Milling ◽  
Coexistence Of Phases ◽  
Nonequilibrium Conditions ◽  
Diffraction Patterns ◽  
Spinel Structures ◽  
Highly Porous ◽  
Standard Techniques

Oxide mixtures which feature a coexistence of phases with the wüstite and spinel structures are considered model systems for the study of solid-state reaction kinetics, phase boundaries, and thin-film growth, and such systems are especially suited to TEM studies. (In this paper, the terms “wüstite” and “spinel” will refer to phases of those structure types.) The study of wüstite-spinel coexistence has been limited mostly to systems near their equilibrium condition, where the assumptions of local thermodynamic equilibrium are valid. The cation-excess spinels of the type Ni2(1+x)Ti1-xO4, which reportedly exist only above 1375°C4, provide an excellent system for the study of wüstite-spinel coexistence under highly nonequilibrium conditions. The nature of these compounds has been debated in the literature. X-ray and neutron powder diffraction patterns have been used to advocate the existence of a single-phase, non- stoichiometric spinel. TEM studies of the microstructure have been used to suggest equilibrium coexistence of a stoichiometric spinel, Ni2TiO4, and a wüstite phase; this latter study has shown a coexistence of wüstite and spinel phases in specimens thought to have been composed of a single, non- stoichiometric spinel phase. The microstructure and nature of this phase coexistence is the focus of this study. Specimens were prepared by ball-milling a mixture of NiO and TiO2 powders with 10 wt.% TiO2. The mixture was fired in air at 1483°C for 5 days, and then quenched to room temperature. The aggregate thus produced was highly porous, and needed to be infiltrated prior to TEM sample preparation, which was performed using the standard techniques of lapping, dimpling, and ion milling.

Analysis of Sputtered Zinc Oxide Films

1980 ◽  
Vol 38 ◽  
pp. 416-417
Author(s):  
T. A. Emma ◽  
M. P. Singh
Keyword(s):  
Electron Microscopy ◽  
Zinc Oxide ◽  
Piezoelectric Materials ◽  
Oxide Films ◽  
Optical Quality ◽  
Zno Films ◽  
Rf Power ◽  
X Ray Diffraction ◽  
Sputtered Films ◽  
Zinc Oxide Films

Optical quality zinc oxide films have been characterized using reflection electron diffraction (RED), replication electron microscopy (REM), scanning electron microscopy (SEM), and X-ray diffraction (XRD). Significant microstructural differences were observed between rf sputtered films and planar magnetron rf sputtered films. Piezoelectric materials have been attractive for applications to integrated optics since they provide an active medium for signal processing. Among the desirable physical characteristics of sputtered ZnO films used for this and related applications are a highly preferred crystallographic texture and relatively smooth surfaces. It has been found that these characteristics are very sensitive to the type and condition of the substrate and to the several sputtering parameters: target, rf power, gas composition and substrate temperature.

Persistent photoconductivity in uniforndy and selectively silicon doped AlAs / GaAs short period superlattices

1991 ◽  
Vol 1 (4) ◽  
pp. 503-510 ◽  
Author(s):  
P. Jeanjean ◽  
J. Sicart ◽  
J. L. Robert ◽  
F. Mollot ◽  
R. Planel
Keyword(s):  
Persistent Photoconductivity ◽  
Short Period ◽  
Short Period Superlattices ◽  
Silicon Doped

Persistent Photoconductivity And Thermal Recovery Kinetics Of Low Energy Ar + Bombarded GaAs

1991 ◽  
Vol 223 ◽  
Author(s):  
A. Vaseashta ◽  
L. C. Burton
Keyword(s):  
Deep Level Transient Spectroscopy ◽  
Deep Level ◽  
Thermal Recovery ◽  
Low Energy ◽  
Persistent Photoconductivity ◽  
Transport Parameters ◽  
Excellent Correlation ◽  
Proposed Model ◽  
Transient Spectroscopy ◽  
Kinetics Of

ABSTRACTKinetics of persistent photoconductivity, photoquenching, and thermal and optical recovery observed in low energy Ar+ bombarded on (100) GaAs surfaces have been investigated. Rate and transport equations for these processes were derived and simulated employing transport parameters, trap locations and densities determined by deep level transient spectroscopy. Excellent correlation was obtained between the results of preliminary simulation and the experimentally observed values. The exponential decay of persistent photoconductivity response curve was determined to be due to metastable electron traps with longer lifetime and is consistent with an earlier proposed model.

Low Temperature Deposition of Zinc Oxide Films

2003 ◽  
Vol 763 ◽  
Author(s):  
H. W. Lee ◽  
Y. G. Wang ◽  
S. P. Lau ◽  
B. K. Tay
Keyword(s):  
Zinc Oxide ◽  
Carrier Concentration ◽  
Vacuum Arc ◽  
Zno Films ◽  
Al Alloy ◽  
Pure Zinc ◽  
Zinc Oxide Films ◽  
Alloy Target ◽  
Temperature Deposition ◽  
Filtered Cathodic Vacuum Arc

AbstractA detailed study of zinc oxide (ZnO) films prepared by filtered cathodic vacuum arc (FCVA) technique was carried out. To deposit the films, a pure zinc target was used and O2 was fed into the chamber. The electrical properties of both undoped and Al-doped ZnO films were studied. For preparing the Al-doped films, a Zn-Al alloy target with 5 wt % Al was used. The resistivity, Hall mobility and carrier concentration of the samples were measured. The lowest resistivity that can be achieved with undoped ZnO films was 3.4×10-3 Ωcm, and that for Al-doped films was 8×10-4 Ωcm. The carrier concentration was found to increase with Al doping.

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