Influence of Surface Electrode on Luminescent Properties of Nanocrystalline Silicon Electroluminescent Device

2007 ◽  
Vol 7 (2) ◽  
pp. 653-657 ◽  
Author(s):  
Keisuke Sato ◽  
Kenji Hirakuri
Keyword(s):  
Film Thickness ◽  
Indium Tin Oxide ◽  
Luminescent Properties ◽  
Nanocrystalline Silicon ◽  
Surface Electrode ◽  
High Brightness ◽  
Au Electrode ◽  
Ito Electrode ◽  
Order Of Magnitude ◽  
Red Luminescence

We describe the electrical and luminescence properties of nanocrystalline silicon (nc-Si) based red electroluminescent (EL) devices using an indium tin oxide (ITO) and/or gold (Au) films as a surface electrode, and the variation in the transmittance and resistivity of two electrodes with various film thicknesses. The increase in the film thickness from 50 to 200 nm of the ITO electrode led to the lowering of resistivity from 2.0 × 10−3 to 9.1 × 10−4 Ω cm and almost the same value (83–92%) of transmittance in the red region. On the other hand, the Au electrode was lowered the resistivity from 1.8 × 10−4 to 1.6 × 10−5 Ωcm and the transmittance in the red region from 42 to 1.8% with increasing the film thickness from 10 to 80 nm. Moreover, the red luminescence from the EL devices using the ITO and/or Au electrodes having thickness of 200 and 10 nm, respectively, obtained by applying the direct current forward voltage above 4.5 and 2.5 V and/or by flowing the forward current density above 53 and 38 mA/cm2, respectively. However, the luminescence intensity of EL device with the ITO electrode strengthened more than about one order of magnitude in comparison to that of the EL device with the Au electrode. This was due to the high value of transmittance in the red region of the ITO electrode. We suggest that the ITO electrode is an optimum surface electrode for the realization of nc-Si based EL device with the high brightness.

Improvement of Operating Voltage and Luminescent Properties in Nanocrystalline Silicon Electroluminescent Device

2004 ◽  
Vol 832 ◽  
Author(s):  
K. Sato ◽  
K. Hirakuri ◽  
T. Izumi
Keyword(s):  
Silicon Dioxide ◽  
Hydrofluoric Acid ◽  
Luminescent Properties ◽  
Nanocrystalline Silicon ◽  
Operating Voltage ◽  
Si Substrate ◽  
Naked Eye ◽  
Order Of Magnitude ◽  
Red Luminescence ◽  
Nanocrystalline Si

ABSTRACTWe have investigated direct current (DC) operating voltage and luminescence properties of electroluminescent (EL) devices with and/or without a silicon dioxide (SiO2) layer in nanocrystalline Si (nc-Si) region/Si substrate interface. The device with the SiO2 layer showed red luminescence with a peak at 670 nm by applying the DC operating voltage above 4.0 V. When the SiO2 layer in the device was completely removed by the hydrofluoric acid (HF) treatment, the red luminescence from the device was observed at the DC operating voltage of 2.0 V. Moreover, the luminescent intensity was also increased more than one order of magnitude, because carriers were efficiently and easily injected into the nc-Si region by the removal of SiO2 layer. The red luminescence from the device could be clearly seen with the naked eye under the DC operating voltage above 3.0 V. These results indicate that the removal of SiO2 layer leads to the lowering of DC operating voltage and increase of luminance for the nc-Si based EL device.

Influence of Oxidized Layer on Operating Voltage and Luminance of Nanocrystalline Silicon Electroluminescent Device

2006 ◽  
Vol 6 (1) ◽  
pp. 200-204 ◽  
Author(s):  
Keisuke Sato ◽  
Kenji Hirakuri
Keyword(s):  
Luminescence Intensity ◽  
Luminescence Property ◽  
Radiative Recombination ◽  
Nanocrystalline Silicon ◽  
Operating Voltage ◽  
Si Substrate ◽  
Order Of Magnitude ◽  
Recombination Centers ◽  
Red Luminescence ◽  
Nanocrystalline Si

A direct current (DC) operating voltage and luminescence property of red electroluminescent (EL) devices with and/or without a silicon dioxide (SiO2) layer at interface between nanocrystalline Si(nc-Si) region and Si substrate has investigated. The removal of SiO2 layer in the EL device led to the lowering of DC operating voltage from 4.0 up to 2.0 V and the increase of luminescence intensity more than one order of magnitude. The external quantum efficiency of red luminescence from the EL device without the SiO2 layer at the DC operating voltage of 3.0 V was 0.5%. These were realized by the efficient and easy injection of carriers to the radiative recombination centers in the nc-Si region due to the removal of SiO2 layer. These results indicate that the removal of SiO2 layer is drastically improved the DC operating voltage and luminescence intensity for the nc-Si based EL device.

Steady State Photoconductivity in Conjugated Polymers

2001 ◽  
Vol 665 ◽  
Author(s):  
C. D. Sitch ◽  
D. P. Halliday ◽  
A. P. Monkman
Keyword(s):  
Steady State ◽  
Conjugated Polymers ◽  
Tin Oxide ◽  
Indium Tin Oxide ◽  
Bulk Polymer ◽  
Au Electrode ◽  
Ito Electrode

ABSTRACTVisible and ultraviolet photoconductivity (PC) measurements have been performed on thick (7[.proportional]m) and thin (170nm) films of poly[2-methoxy, 5 ethyl (2' hexyloxy) paraphenylenevinylene] (MEH-PPV) sandwiched between indium tin oxide (ITO) and semitransparent gold (Au) electrodes. PC spectra were obtained for samples under different bias polarities and for illumination through the ITO electrode and through the Au electrode. The results obtained indicate that the absorbed photons form excitons that dissociate extrinsically at or near the electrodes to form hole polarons or intrinsically at higher photon energies in the bulk polymer.

Giant Anisotropy of Conductivity in Hydrogenated Nanocrystalline Silicon Thin Films

1998 ◽  
Vol 536 ◽  
Author(s):  
A. B. Pevtsov ◽  
N. A. Feoktistov ◽  
V. G. Golubev
Keyword(s):  
Thin Films ◽  
Film Thickness ◽  
Percolation Theory ◽  
Nanocrystalline Silicon ◽  
Spatial Light Modulators ◽  
Light Emitting ◽  
Light Modulators ◽  
Silicon Thin Films ◽  
Longitudinal Conductivity ◽  
Transverse Conductivity

AbstractThin (<1000 Å) hydrogenated nanocrystalline silicon films are widely used in solar cells, light emitting diodes, and spatial light modulators. In this work the conductivity of doped and undoped amorphous-nanocrystalline silicon thin films is studied as a function of film thickness: a giant anisotropy of conductivity is established. The longitudinal conductivity decreases dramatically (by a factor of 109 − 1010) as the layer thickness is reduced from 1500 Å to 200 Å, while the transverse conductivity remains close to that of a doped a- Si:H. The data obtained are interpreted in terms of the percolation theory.

High-Density Memristor-CMOS Ternary Logic Family

2020 ◽  
Author(s):  
Xiaoyuan Wang ◽  
Pengfei Zhou ◽  
Jason Eshraghian ◽  
Chih-Yang Lin ◽  
Herbert Ho-Ching Iu ◽  
...  
Keyword(s):  
Indium Tin Oxide ◽  
Practical Implementation ◽  
Switching Speed ◽  
High Data ◽  
Fast Switching ◽  
Data Density ◽  
Order Of Magnitude ◽  
High Transconductance ◽  
Logic Functions ◽  
Magnitude Improvement

<div>This paper presents the first experimental demonstration</div><div>of a ternary memristor-CMOS logic family. We systematically</div><div>design, simulate and experimentally verify the primitive</div><div>logic functions: the ternary AND, OR and NOT gates. These are then used to build combinational ternary NAND, NOR, XOR and XNOR gates, as well as data handling ternary MAX and MIN gates. Our simulations are performed using a 50-nm process which are verified with in-house fabricated indium-tin-oxide memristors, optimized for fast switching, high transconductance, and low current leakage. We obtain close to an order of magnitude improvement in data density over conventional CMOS logic, and a reduction of switching speed by a factor of 13 over prior state-of-the-art ternary memristor results. We anticipate extensions of this work can realize practical implementation where high data density is of critical importance.</div>

scholarly journals Optoelectronic Properties of Ultrathin Indium Tin Oxide Films: A First-Principle Study

Crystals ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 30
Author(s):  
Xiaoyan Liu ◽  
Lei Wang ◽  
Yi Tong
Keyword(s):  
Film Thickness ◽  
Tin Oxide ◽  
Indium Tin Oxide ◽  
Density Functional ◽  
Optoelectronic Properties ◽  
Surface Strain ◽  
Strain Effect ◽  
First Principle ◽  
Electrical Resistivities ◽  
Ito Films

First-principle density functional theory simulations have been performed to predict the electronic structures and optoelectronic properties of ultrathin indium tin oxide (ITO) films, having different thicknesses and temperatures. Our results and analysis led us to predict that the physical properties of ultrathin films of ITO have a direct relation with film thickness rather than temperature. Moreover, we found that a thin film of ITO (1 nm thickness) has a larger absorption coefficient, lower reflectivity, and higher transmittance in the visible light region compared with that of 2 and 3 nm thick ITO films. We suggest that this might be due to the stronger surface strain effect in 1 nm thick ITO film. On the other hand, all three thin films produce similar optical spectra. Finally, excellent agreement was found between the calculated electrical resistivities of the ultrathin film of ITO and that of its experimental data. It is concluded that the electrical resistivities reduce along with the increase in film thickness of ITO because of the short strain length and limited bandgap distributions.

scholarly journals Performance of GaN-Based LEDs with Nanopatterned Indium Tin Oxide Electrode

2016 ◽  
Vol 2016 ◽  
pp. 1-7
Author(s):  
Zhanxu Chen ◽  
Wenjie Liu ◽  
Wei Wan ◽  
Gengyan Chen ◽  
Yongzhu Chen ◽  
...  
Keyword(s):  
Tin Oxide ◽  
Indium Tin Oxide ◽  
Ohmic Contacts ◽  
Three Dimensional ◽  
Light Output ◽  
Light Extraction Efficiency ◽  
Experimental Result ◽  
Indium Tin Oxide Electrode ◽  
Light Emitting ◽  
Ito Electrode

The indium tin oxide (ITO) has been widely applied in light emitting diodes (LEDs) as the transparent current spreading layer. In this work, the performance of GaN-based blue light LEDs with nanopatterned ITO electrode is investigated. Periodic nanopillar ITO arrays are fabricated by inductive coupled plasma etching with the mask of polystyrene nanosphere. The light extraction efficiency (LEE) of LEDs can be improved by nanopatterned ITO ohmic contacts. The light output intensity of the fabricated LEDs with nanopatterned ITO electrode is 17% higher than that of the conventional LEDs at an injection current of 100 mA. Three-dimensional finite difference time domain simulation matches well with the experimental result. This method may serve as a practical approach to improving the LEE of the LEDs.

scholarly journals Fabrication of New Liquid Crystal Device Using Layer-by-Layer Thin Film Process

Processes ◽  
2018 ◽  
Vol 6 (8) ◽  
pp. 108 ◽  
Author(s):  
Gitae Moon ◽  
Wonjun Jang ◽  
Intae Son ◽  
Hyun Cho ◽  
Yong Park ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Indium Tin Oxide ◽  
Film Growth ◽  
Mechanical Stability ◽  
Liquid Crystal Display ◽  
Layer By Layer ◽  
Transparent Electrodes ◽  
Ito Electrode ◽  
Display Performance ◽  
Layer Thin Film

Indium tin oxide (ITO) transparent electrodes are troubled with high cost and poor mechanical stability. In this study, layer-by-layer (LBL)-processed thin films with single-walled carbon nanotubes (SWNTs) exhibited high transparency and electrical conductivity as a candidate for ITO replacement. The repetitive deposition of polycations and stabilized SWNTs with a negative surfactant exhibits sufficiently linear film growth and high optoelectronic performance to be used as transparent electrodes for vertically aligned (VA) liquid crystal display (LCD) cells. The LC molecules were uniformly aligned on the all of the prepared LBL electrodes. VA LCD cells with SWNT LBL electrodes exhibited voltage-transmittance (V-T) characteristics similar to those with the conventional ITO electrodes. Although the response speeds were slower than the LCD cell with the ITO electrode, as the SWNT layers increased, the display performance was closer to the LCD cells with conventional ITO electrode. This work demonstrated the good optoelectronic performance and alignment compatibility with LC molecules of the SWNT LBL assemblies, which are potential alternatives to ITO films as transparent electrodes for LCDs.

scholarly journals Different electrode anodes used in OLED devices Diferentes eletrodos anodos usados em dispositivos OLEDs

2021 ◽  
Author(s):  
Emerson Roberto Santos ◽  
Thiago de Carvalho Fullenbach ◽  
Marina Sparvoli Medeiros ◽  
Luis da Silva Zambom ◽  
Roberto Koji Onmori ◽  
...  
Keyword(s):  
Thin Films ◽  
Tin Oxide ◽  
Threshold Voltage ◽  
Indium Tin Oxide ◽  
Light Emitting Diode ◽  
Electrical Current ◽  
High Threshold ◽  
Diamond Coatings ◽  
Ito Thin Films ◽  
Order Of Magnitude

Transparent conductive oxides (TCOs) known as indium tin oxide (ITO) and fluorine tin oxide (FTO) deposited on glass were compared by different techniques and also as anodes in organic light-emitting diode (OLED) devices with same structure. ITO produced at laboratory was compared with the commercial one manufactured by different companies: Diamond Coatings, Displaytech and Sigma-Aldrich, and FTO produced at laboratory was compared with the commercial one manufactured by Flexitec Company. FTO thin films produced at laboratory presented the lowest performance measured by Hall effect technique and also by I-V curve of OLED device with low electrical current and high threshold voltage. ITO thin films produced at laboratory presented elevated sheet resistance in comparison with commercial ITOs (approximately one order of magnitude greater), that can be related by a high number of defects as discontinuity of the chemical lattice or low crystalline structure. In the assembly of OLED devices with ITO and FTO produced at laboratory, neither presented luminances. ITO manufactured by Sigma-Aldrich company presented better electrical and optical characteristics, as low electrical resistivity, good wettability, favorable transmittance, perfect physicalchemical stability and lowest threshold voltage (from 3 to 4.5 V) for OLED devices.

Optimization of p-type Nanocrystalline Silicon Thin Films for Solar Cells and Photodiodes

2009 ◽  
Vol 1153 ◽  
Author(s):  
Yuri Vygranenko ◽  
Ehsanollah Fathi ◽  
Andrei Sazonov ◽  
Manuela Vieira ◽  
Gregory Heiler ◽  
...  
Keyword(s):  
Thin Films ◽  
Film Thickness ◽  
Chemical Vapor ◽  
Percolation Cluster ◽  
Nanocrystalline Silicon ◽  
Film Structure ◽  
Silicon Thin Films ◽  
Low Leakage ◽  
In Doping ◽  
P Type

AbstractWe report on structural, electronic, and optical properties of boron-doped, hydrogenated nanocrystalline silicon (nc-Si:H) thin films deposited by plasma-enhanced chemical vapor deposition (PECVD) at a substrate temperature of 150°C. Film properties were studied as a function of trimethylboron-to-silane ratio and film thickness. The film thickness was varied in the range from 14 to 100 nm. The conductivity of 60 nm thick films reached a peak value of 0.07 S/cm at a doping ratio of 1%. As a result of amorphization of the film structure, which was indicated by Raman spectra measurements, any further increase in doping reduced conductivity. We also observed an abrupt increase in conductivity with increasing film thickness ascribed to a percolation cluster composed of silicon nanocrystallites. The absorption loss of 25% at a wavelength of 400 nm was measured for the films with optimized conductivity deposited on glass and glass/ZnO:Al substrates. A low-leakage, blue-enhanced p-i-n photodiode with an nc-Si p-layer was also fabricated and characterized.

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