High-Quality A-Si Films Prepared by the Direct Photo-Cvd Method

1989 ◽  
Vol 149 ◽  
Author(s):  
S. Nakano ◽  
K. Wakisaka ◽  
M. Kameda ◽  
M. Isomura ◽  
T. Matsuyama ◽  
...  
Keyword(s):  
High Efficiency ◽  
Defect States ◽  
Low Light ◽  
High Quality ◽  
Characteristic Energy ◽  
Area Efficiency ◽  
Cvd Method ◽  
Si Solar Cell ◽  
Si Films

ABSTRACTA high-efficiency integrated-type a-Si solar cell submodule with a size of 10cm × 10cm has been fabricated and a total area efficiency of 9.6% is obtained by using a high-quality p-layer doped with B(CH3)3 We have developed an advanced direct photo-CVD method. High-quallt” a-SI films with low tail characteristic energy and low light-induced degradation is prepared by this method. We have also studied the role of Si-H2 bonds on the light-induced effect. The result implies that Si-H bonds stabilize the defect states, resulting in a large light-induced degradation.

High-Quality a-Si-Based Alloys : a-SiGe Films Fabricated in a Super Chamber and Superlattice Structure a-Si Films Prepared by a Photo-CVD Method

1987 ◽  
Vol 95 ◽  
Author(s):  
Shinya Tsuda ◽  
Hisao Haku ◽  
Hisaki Tarui ◽  
Takao Matsuyama ◽  
Katsunobu Sayama ◽  
...  
Keyword(s):  
Conversion Efficiency ◽  
Photovoltaic Effect ◽  
High Vacuum ◽  
Reaction Chamber ◽  
Wide Bandgap ◽  
Ultra High Vacuum ◽  
High Quality ◽  
Cvd Method ◽  
Superlattice Structure ◽  
Si Films

AbstractIn order to improve the conversion efficiency of a-Si solar cells, high-quality a-Si based alloys of both narrow handgap and wide bandgap were studied.Concerning the narrow bandgap material, we found a particular dependence of film qualities on substrate temperature. In addition, high-quality a-SiGe:H films were obtained by using a super chamber (separated ultra-high vacuum reaction chamber).As for the high-quality wide bandgap material, a-Si/a-SiC superlattice structure films fabricated by a photo-CVD method were studied for the first time. From the analysis of their properties, we found that the superlattice structure p-layer was an active layer for photovoltaic effect. A conversion efficiency of 11.2% has been obtained for a pin a-Si solar cell whose player was of the superlattice structure.

High Quality a-Si Films and Superlattice Structure p-Layer a-Si Solar Cells

1986 ◽  
Vol 70 ◽  
Author(s):  
Shoichi Nakano ◽  
Shinya Tsuda ◽  
Hisaki Tarui ◽  
Tsuyoshi Takahama ◽  
Hisao Haku ◽  
...  
Keyword(s):  
Solar Cells ◽  
Conversion Efficiency ◽  
Reaction Chamber ◽  
High Quality ◽  
Cvd Method ◽  
Superlattice Structure ◽  
Si Solar Cells ◽  
New Material ◽  
Si Films ◽  
First Time

ABSTRACTAs a new preparation method for high-quality a-Si films, we have developed the super chamber, a separated UHV reaction chamber system. A low impurity concentration and excellent film properties were obtained by the super chamber. A conversion efficiency of 11.7% was obtained for an a-Si solar cell using a high-quality i-layer deposited by the super chamber, and a p-layer fabricated by a photo-CVD method.As a new material, amorphous superlattice structure films were fabricated by the photo-CVD method for the first time. Quantization effects and low damage to the interfaces were observed. Superlattice structure p-layer a-Si solar cells were fabricated for the first time, and a conversion efficiency of 10.5% was obtained.

Preparation of High-Quality poly-Si and μc-Si Films by the SPC Method

1989 ◽  
Vol 164 ◽  
Author(s):  
T. Matsuyama ◽  
M. Nishikuni ◽  
M. Kameda ◽  
S. Okamoto ◽  
M. Tanaka ◽  
...  
Keyword(s):  
Solar Cell ◽  
Conversion Efficiency ◽  
Solid Phase ◽  
Wavelength Region ◽  
Optical Transmittance ◽  
High Quality ◽  
Long Wavelength ◽  
Si Solar Cell ◽  
Si Films ◽  
P Type

AbstractWe have achieved the highest total area conversion efficiency for an integrated type 10cm × 10cm a-Si solar cell at 10.2%. This value is the world record for a 10cm × 10cm a-Si solar cell. For further improvement of conversion efficiency in a-Si solar cells, it is necessary to develop materials with high-photosensitivity in the long wavelength region and materials with high conductivity. We have developed a Solid Phase Crystallization (SPC) method of growing a Si crystal at temperatures as low as 600°C. Using this method, thin-film polycrystalline silicon (poly-Si) with higP-photosensitivity in the long wavelength region and Hall mobility of 70cm2/V sec was obtained and quantum efficiency in the range of 800,∼ lO00nm was achieved up to 80% in the n-type poly-Si with grain size of about 2μm. We also succeeded in preparing a device-quality p-type microcrystalline silicon (μc-Si) using the SPC method at 620°C for 3 hours from the conventional plasma-CVD p-type amorphous silicon (a-5i) withoul using any post-doping process. Obtained properties of μd=2 × 103 (.cm) and a high optical transmittance in the 2.0 ∼ 3.0 eV range are better as a window material than the conventional p-type μc-Si:H. Therefore, it was concluded that the SPC method is better as a new technique to prepare high-quality solar cell materials.

Achievement of More than 10% Efficiency for a Single-Junction 100cm2 a-Si Solar Cell and Development of a New-Type Module Structure

1990 ◽  
Vol 192 ◽  
Author(s):  
Yoshihiro Hishikawa ◽  
Michitoshe Ohnishi ◽  
Yukinori Kuwano
Keyword(s):  
Solar Cell ◽  
Output Power ◽  
Conversion Efficiency ◽  
High Efficiency ◽  
Module Structure ◽  
High Quality ◽  
Single Junction ◽  
Si Solar Cell ◽  
New Type

ABSTRACTA total area conversion efficiency of 10.2% has been achieved for a 1Ocm×1Ocm integrated-type single-junction amorphous silicon (a-Si) solar cell submodule. It is the highest conversion efficiency ever reported for an a-Si solar cell with an area of 100cm2, including multi-junction cells. The effective area conversion efficiency is as high as 11.3%. The high efficiency is obtained by improving the quality of the i-layer and the p/i buffer layer, as well as by utilizing a highly textured, high-quality transparent electrode. The quality of the i-layer plays a dominant role in the performance of a-Si solar cells, especially in high efficiency cells. Techniques that control the properties of the high-quality a-Si films for the i-layer are described. Electric conductivity, ESR spin density and the Raman spectra of high-quality a-Si:H films are investigated as well as their thickness-dependence and substrate-dependence.A Through-Hole Contact (THC) integrated-type submodule has been developed as a new-type a-Si solar cell module structure. Numerical simulations on the output power of the structure show that the output power can be significantly improved by the THC structure.

Surface-reduced Si-doped TiO2 nanotubes for high-efficiency photoelectrochemical water splitting

2019 ◽  
Vol 12 (06) ◽  
pp. 1940004
Author(s):  
Dawei Si ◽  
Zhenbiao Dong ◽  
Ting Li ◽  
Dongyan Ding ◽  
Congqin Ning
Keyword(s):  
Water Splitting ◽  
High Efficiency ◽  
Photocurrent Density ◽  
Reduction Reaction ◽  
Photoelectrochemical Water Splitting ◽  
Defect States ◽  
Photogenerated Electrons ◽  
Long Time ◽  
Si Doped

TiO2 is a promising photocatalyst in the reaction of water splitting for hydrogen. Here, we used NaBH4 reduction reaction to introduce [Formula: see text]/VO defect states into Si-doped TiO2 nanotubes and investigated the photoelectrochemical water splitting properties. It was found that the photocatalytic activity was improved through NaBH4 reduction because of the existence of [Formula: see text]/VO. The defect states ([Formula: see text]/VO) could play a role of capture trap and accelerate the separation of photogenerated electrons and holes. The photocurrent density of the Si-doped TiO2 nanotubes reduced for 3[Formula: see text]h was 1.5[Formula: see text]mA/cm2 compared to 0.7[Formula: see text]mA/cm2 of the unreduced nanotubes. The conversion efficiency was 0.7%, which was almost 4 times than that of pure TiO2. On the other hand, reduction for a long time would generate excess defect states and thus cause the decrease of photocurrent density. Excess defect states could act as the recombination centers of photogenerated electrons and holes.

Photoluminescence and Photoluminescence Excitation Spectroscopy of Cu(In,Ga)Se2 Thin Films

2009 ◽  
Vol 1165 ◽  
Author(s):  
Damon N. Hebert ◽  
Julio A. N. T. Soares ◽  
Angus A. Rockett
Keyword(s):  
Thin Films ◽  
Radiative Recombination ◽  
High Efficiency ◽  
Photoluminescence Excitation ◽  
Defect States ◽  
Band Tail ◽  
Shallow Defect ◽  
Shallow State

AbstractThe role of intrinsic point defects on radiative recombination in Cu(In,Ga)Se2 thin films was investigated by photoluminescence (PL) and photoluminescence excitation (PLE) spectroscopies. Experiments were performed on device-grade polycrystalline layers and single crystal thin films. PL transitions identified by others as indicating a shallow state with an ionization energy of ∼16 meV is proposed to be a transition into band tail states rather than a distinct shallow defect. The presence of deep levels contributing to radiative recombination does not necessarily preclude the material from producing a high efficiency device and may suggest the absence of dominant non-radiative recombination pathways. The band edge width as measured by PLE and the separation of this edge from defect states are suggested to be potentially effective indicators of the quality of a material. Luminescence that appears to be connected with the absence of Na in the growth process persists in high Ga alloy, Na containing materials, suggesting that Na may become ineffective in passivating or eliminating certain defects in high Ga material.

Sub-gap Photoconductivity in Germanium-silicon Films Deposited by Low Frequency Plasma

2010 ◽  
Vol 1245 ◽  
Author(s):  
Andrey Kosarev ◽  
Francisco Avila
Keyword(s):  
Photon Energy ◽  
Low Frequency ◽  
Chemical Vapor ◽  
Defect States ◽  
Constant Intensity ◽  
Characteristic Energy ◽  
Frequency Plasma ◽  
Device Applications ◽  
Si Films ◽  
Germanium Silicon

Abstract(GexSi1-x:H) films are of much interest for many device applications because of narrow band gap and compatibility with films deposited by plasma. However, electronic properties of GexSi1-x:H films for high Ge content x > 0.5 have been studied less than those of Si films. In this work, we present a study of sub-gap photoconductivity (σpc) in GexSi1-x:H films for x = 1 and x = 0.97 deposited by low frequency plasma enhanced chemical vapor deposition (LF PECVD) with both various H-dilution (RH) during growth (non-doped films) and boron (B) incorporation in the films. Spectra of sub-gap photoconductivity σpc(hν) were measured in the photon energy range of hν = 0.6 to 1.8 eV. σpc(hν) spectra were normalized to constant intensity. For hν < Eg two regions in σpc(hν) can be distinguished: “A”, where σpc is related to transitions between tail and extended states, and “B”, where photoconductivity is due to defect states. σpc(hν) in ”A” region showed exponential behavior that could be described by some characteristic energy EUPC similar to Urbach energy EU in spectral dependence of optical absorption. EUPC > EU was observed in all the films studied. This together with higher relative values (i.e. normalized by the maximum value at hν = Eg) for photoconductivity comparing with those for α means that mobility-lifetime product (μτ) depends on photon energy μτ = f(hν) that was determined from α(hν)and σpc(hν). μτ(hν) increases by factor of 20 to 40 depending on the sample with reducing hν from 1.1 to 0.7 eV. In some samples, this dependence was monotonous, while in others demonstrated maxima related to both interference and density of states. Effects of both RH and boron incorporation have been found and are discussed.

Making Movies and Community of Talent

2019 ◽  
Vol 10 (11) ◽  
pp. 1057-1064
Author(s):  
Katsuhiko Hirasawa ◽  
Keyword(s):  
Shop Floor ◽  
High Quality ◽  
Democratic Leadership ◽  
Staff Members

Staff members at a movie company Daiei, known for presumably the world’s best film technology, continued to produce movies for several months even after the company went bankrupt. It was because they desired to make outstanding films. A director can create a high-quality film by combining the skills and ideas of such staff. Akira Kurosawa named the group that could produce excellent works the “Community of Talents”. By using research on a community as a clue, this paper aims to highlight how the “Community of Talents” is organized. First I point out that a “Community of Talents” is formulated primarily by the labor of the staff based on Kumazawa’s “Community on the Shop Floor”. The paper subsequently refers to research by Heinrich Nicklish, a representative researcher on the study of community in Germany, in an attempt to verify that the community is a group of people established on functions. Lastly, the paper explores Guido Fisher’s research to reveal the role of democratic leadership centered on the director who transforms the objectified staff in the organization into an independently-minded presence and help them prove their abilities. The paper continues to emphasize the significance of leadership in the formation of the “Community of Talents”.

Clustering-Triggered Efficient Room Temperature Phosphorescence from Nonconventional Luminophores

2019 ◽  
Author(s):  
Shuyuan Zheng ◽  
Taiping Hu ◽  
Xin Bin ◽  
Yunzhong Wang ◽  
Yuanping Yi ◽  
...  
Keyword(s):  
Room Temperature ◽  
High Efficiency ◽  
Spin Orbit Coupling ◽  
Design Rationale ◽  
Emission Mechanism ◽  
Room Temperature Phosphorescence ◽  
Electronic Interactions ◽  
Energy Gaps ◽  
Theoretical Results

Pure organic room temperature phosphorescence (RTP) and luminescence from nonconventional luminophores have gained increasing attention. However, it remains challenging to achieve efficient RTP from unorthodox luminophores, on account of the unsophisticated understanding of the emission mechanism. Here we propose a strategy to realize efficient RTP in nonconventional luminophores through incorporation of lone pairs together with clustering and effective electronic interactions. The former promotes spin-orbit coupling and boost the consequent intersystem crossing, whereas the latter narrows energy gaps and stabilizes the triplets, thus synergistically affording remarkable RTP. Experimental and theoretical results of urea and its derivatives verify the design rationale. Remarkably, RTP from thiourea solids with unprecedentedly high efficiency of up to 24.5% is obtained. Further control experiments testify the crucial role of through-space delocalization on the emission. These results would spur the future fabrication of nonconventional phosphors, and moreover should advance understanding of the underlying emission mechanism.<br>

When Do Auditors Use Specialists' Work to Improve Problem Representations of and Judgments about Complex Estimates?

2017 ◽  
Vol 93 (4) ◽  
pp. 177-202 ◽  
Author(s):  
Emily E. Griffith
Keyword(s):  
Pattern Recognition ◽  
Situational Factors ◽  
Situational Factor ◽  
High Quality ◽  
Quality Audit ◽  
Domain Specific ◽  
Epistemic Motivation ◽  
Specific Expertise ◽  
Problem Representations

ABSTRACT Auditors are more likely to identify misstatements in complex estimates if they recognize problematic patterns among an estimate's underlying assumptions. Rich problem representations aid pattern recognition, but auditors likely have difficulty developing them given auditors' limited domain-specific expertise in this area. In two experiments, I predict and find that a relational cue in a specialist's work highlighting aggressive assumptions improves auditors' problem representations and subsequent judgments about estimates. However, this improvement only occurs when a situational factor (e.g., risk) increases auditors' epistemic motivation to incorporate the cue into their problem representations. These results suggest that auditors do not always respond to cues in specialists' work. More generally, this study highlights the role of situational factors in increasing auditors' epistemic motivation to develop rich problem representations, which contribute to high-quality audit judgments in this and other domains where pattern recognition is important.

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