Controlling Structural Evolution by VHF Power Profiling Technique for High-efficiency Microcrystalline Silicon Solar Cells at High Deposition Rate

2009 ◽  
Vol 1153 ◽  
Author(s):  
Guofu Hou ◽  
Xiaoyan Han ◽  
Changchun Wei ◽  
Xiaodan Zhang ◽  
Guijun Li ◽  
...  
Keyword(s):  
Solar Cells ◽  
Solar Cell ◽  
Deposition Rate ◽  
High Efficiency ◽  
Structural Evolution ◽  
High Rate ◽  
High Deposition Rate ◽  
Microcrystalline Silicon ◽  
Solar Cell Performance ◽  
Power Profiling

AbstractHigh rate deposition of hydrogenated microcrystalline silicon (μc-Si:H) films and solar cells were prepared by very high frequency plasma enhanced chemical vapor deposition (VHF-PECVD) process in a high power and high pressure regime. The experiment results demonstrate that in high-rate deposited μc-Si:H films, the structural evolution is much more dramatic than that in low-rate deposited μc-Si:H films. A novel VHF power profiling technique, which was designed by dynamically decreasing the VHF power step by step during the deposition of μc-Si:H intrinsic layers, has been developed to control the structural evolution along the growth direction. Another advantage of this VHF power profiling technique is the reduced ion bombardments on growth surface because of decreasing the VHF power. Using this method, a significant improvement in the solar cell performance has been achieved. A high conversion efficiency of 9.36% (Voc=542mV, Jsc=25.4mA/cm2, FF=68%) was obtained for a single junction μc-Si:H p-i-n solar cell with i-layer deposited at deposition rate over 10 �/s.

High-Rate Plasma Process for Microcrystalline Silicon: Over 9% Efficiency Single Junction Solar Cells

2004 ◽  
Vol 808 ◽  
Author(s):  
Takuya Matsui ◽  
Akihisa Matsuda ◽  
Michio Kondo
Keyword(s):  
High Pressure ◽  
Solar Cells ◽  
Solar Cell ◽  
High Efficiency ◽  
Dominant Role ◽  
Short Circuit ◽  
Chemical Vapor ◽  
High Rate ◽  
Microcrystalline Silicon ◽  
Deposition Pressure

ABSTRACTThis paper presents microcrystalline silicon (μ c-Si:H) p-i-n (superstrate-type) solar cells fabricated by 100 MHz plasma-enhanced chemical vapor deposition (PECVD) at i-layer deposition rates of >2 nm/s. Under high-rate conditions, in particular, the deposition pressure is found to play a dominant role in determining short circuit current (Jsc) of solar cell. With anincrease in deposition pressure from 3 to 7-9 Torr, Jsc increases by more than 50% due to a significant improvement in the long wavelength (>600 nm) responses, which essentially leads to high efficiency (∼8%) solar cells in the 2-3 nm/s deposition rate range. Further progress in solar cell efficiency has been made by the improvement of TCO/p and p/i interfaces. As a result, efficiency reaches 9.13% (Jsc=23.7 mA/cm2,Voc=0.528 V,FF=0.73) with a 2.3μm-thick i-layer grown at 2.3 nm/s. Transmission electron microscopy and secondary-ion mass spectroscopy studies reveal that samples prepared at lower pressure (∼4 Torr) comprise many grain boundaries due to disordered grain growth, which induces an anomalous incorporation of atmospheric impurities (predominantly oxygen) after exposing sample to air. In contrast, the high-pressure process (<7 Torr) provides denser grain columns coalesced with [110]-oriented crystallites, which in turn inhibits impurities from penetrating deeper in the film. Based on above results, we propose that the less post-oxidation behavior associated with the denser microstructure of high-pressure-grown μc-Si:H is responsible for the excellent charge collection in p-i-n solar cells.

Growth of Thin μc-Si:H on Intrinsic a-Si:H for Solar Cells Application

1996 ◽  
Vol 452 ◽  
Author(s):  
P. Pemet ◽  
M. Goetz ◽  
H. Keppner ◽  
A. Shah
Keyword(s):  
Stainless Steel ◽  
Solar Cells ◽  
Solar Cell ◽  
High Efficiency ◽  
Solar Cell Performance ◽  
Hydrogenated Silicon ◽  
Boron Doped ◽  
High Efficiency Solar Cells ◽  
Amorphous Substrates ◽  
Interface Treatment

AbstractThe <p> μc-SiC:H / <i> a-Si:H junction can be considered to be a sub-system of a n/i/p solar cell. Optimised performance of this junction can be assumed to be a key feature for obtaining high efficiency solar cells.In this paper the authors present results on the conductivity of boron doped microcrystalline hydrogenated silicon (<p> μc-Si:H) thin films deposited on amorphous substrates (e.g. glass or glass/<i> a-Si:H). It is shown that, without any treatment of the substrate or of the underlying surface, the <p> layers showed a strongly reduced conductivity. This indicates either a bad nucleation or a poor microcrystalline behaviour. By using an appropriate surface treatment of the substrate, a gain in photoconductivity of about three orders of magnitude could be obtained (σ > 3 S/cm at a layer thickness of 400Å). We conclude from this, that for thin <p> type μc-Si:H layers the nucleation conditions are essential for obtaining best electric properties of the film w.r.t. solar cell performance.Based on these results, interface treatment was successfully implemented in n/i/p solar cells deposited on TCO coated glass and stainless steel. The results of these experiments are also presented.

Amorphous Silicon Alloy Materials and Solar Cells Near the Threshold of Microcrystallinity

1999 ◽  
Vol 557 ◽  
Author(s):  
J. Yang ◽  
S. Guha
Keyword(s):  
Solar Cells ◽  
Solar Cell ◽  
Amorphous Silicon ◽  
Triple Junction ◽  
High Efficiency ◽  
Spectral Response ◽  
High Quality ◽  
Silicon Alloys ◽  
Solar Cell Performance ◽  
Hydrogen Dilution

AbstractOne of the most effective techniques used to obtain high quality amorphous silicon alloys is the use of hydrogen dilution during film growth. The resultant material exhibits a more ordered microstructure and gives rise to high efficiency solar cells. As the hydrogen dilution increases, however, a threshold is reached, beyond which microcrystallites begin to form rapidly. In this paper, we review some of the interesting features associated with the thin film materials obtained from various hydrogen dilutions. They include the observation of linear-like objects in the TEM micrograph, a shift of the principal Si TO band in the Raman spectrum, a sharp, low temperature peak in the H2 evolution spectrum, a shift of the wagging mode in the IR spectrum, and a narrowing of the Si (111) peak in the X-ray diffraction pattern. These spectroscopic tools have allowed us to optimize deposition conditions to near the threshold of microcrystallinity and obtain desired high quality materials. Incorporation of the improved materials into device configuration has significantly enhanced the solar cell performance. Using a spectral-splitting, triple-junction configuration, the spectral response of a typical high efficiency device spans from below 350 nm to beyond 950 nm with a peak quantum efficiency exceeding 90%; the triple stack generates a photocurrent of 27 mA/cm2. This paper describes the effect of the improved materials on various solar cell structures, including a 13% active-area, stable triple-junction device.

High-deposition-rate of microcrystalline silicon solar cell by using VHF PECVD

2006 ◽  
Vol 506-507 ◽  
pp. 33-37 ◽  
Author(s):  
Youji Nakano ◽  
Saneyuki Goya ◽  
Toshiya Watanabe ◽  
Nobuki Yamashita ◽  
Yoshimichi Yonekura
Keyword(s):  
Solar Cell ◽  
Deposition Rate ◽  
Silicon Solar Cell ◽  
High Deposition Rate ◽  
Microcrystalline Silicon

Band Discontinuity Effect on a-Si:H and a-SiGe:H Solar Cells

1995 ◽  
Vol 377 ◽  
Author(s):  
X. Xu ◽  
A. Banerjee ◽  
J. Yang ◽  
S. Guha ◽  
K. Vasanth ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Solar Cells ◽  
Solar Cell ◽  
Valence Band ◽  
Cell Performance ◽  
Experimental Results ◽  
Microcrystalline Silicon ◽  
Solar Cell Performance ◽  
Single Junction ◽  
P Type

ABSTRACTThe electrical bandgap of microcrystalline silicon (μc-Si:H) p type layers used in a-Si:H alloy solar cells and the band edge discontinuities between μc-Si:H and a-Si:H alloys have been determined by internal photoemission measurements. The bandgap of μc-Si:H is found to be in the range of 1.50 to 1.57 eV, and the discontinuities at the conduction and the valence band edges are 0 to 0.07 and 0.26 to 0.35 eV, respectively. Use of these parameters in the numerical simulation of single-junction a-Si:H and a-SiGe:H alloy solar cells is found to predict experimental results of solar cell performance.

scholarly journals N-type window layer and its application in high deposition rate microcrystalline silicon solar cells

2009 ◽  
Vol 58 (7) ◽  
pp. 5041
Author(s):  
Zhang Xiao-Dan ◽  
Zhao Ying ◽  
Sun Fu-He ◽  
Wang Shi-Feng ◽  
Han Xiao-Yan ◽  
...  
Keyword(s):  
Solar Cells ◽  
Deposition Rate ◽  
Window Layer ◽  
Silicon Solar Cells ◽  
High Deposition Rate ◽  
Microcrystalline Silicon

High-Efficiency Microcrystalline Silicon and Microcrystalline Silicon-Germanium Alloy Solar Cells

2011 ◽  
Vol 1321 ◽  
Author(s):  
Takuya Matsui ◽  
Michio Kondo
Keyword(s):  
Solar Cells ◽  
Solar Cell ◽  
Silicon Germanium ◽  
High Efficiency ◽  
Chemical Vapor ◽  
Microcrystalline Silicon ◽  
Cell Parameters ◽  
Germanium Alloy ◽  
Doping Technique ◽  
Material Studies

ABSTRACTThis paper presents our material studies on hydrogenated microcrystalline silicon (μc-Si:H) and microcrystalline silicon-germanium alloy (μc-Si1-xGex:H) thin films for the development of high efficiency p-i-n junction solar cells. In μc-Si:H solar cells, we have evaluated the structural properties of the intrinsic μc-Si:H layers grown by plasma-enhanced chemical vapor deposition at high deposition rates (>2 nm/s). Several design criteria for the device grade μc-Si:H are proposed in terms of crystallographic orientation, grain size and grain boundary passivation. Meanwhile, in μc-Si1-xGex:H solar cells, we have succeeded in boosting the infrared response of solar cell upon Ge incorporation up to x∼0.2. Nevertheless, a degradation of solar cell parameters is observed for large Ge contents (x>0.2) and thick i-layers (> 1 μm), which is attributed to the influence of the Ge dangling bonds that act as acceptorlike states in undoped μc-Si1-xGex:H. To improve the device performance, we introduce an oxygen doping technique to compensate the native defect acceptors in μc-Si1-xGex:H p-i-n solar cells.

Preparation of Large Size Pyramidal Texture on N-Type Monocrystalline Silicon Using TMAH Solution for Heterojunction Solar Cells

2012 ◽  
Vol 476-478 ◽  
pp. 1815-1819 ◽  
Author(s):  
Jing Wei Chen ◽  
Lei Zhao ◽  
Su Zhou ◽  
Hong Wei Diao ◽  
Ye Hua Tang ◽  
...  
Keyword(s):  
Solar Cells ◽  
Solar Cell ◽  
Metal Ion ◽  
High Efficiency ◽  
Crystalline Silicon ◽  
Silicon Layer ◽  
Monocrystalline Silicon ◽  
Solar Cell Performance ◽  
Large Size ◽  
Tetra Methyl Ammonium Hydroxide

Pyramidal texture is one traditional method to realize antireflection for c-Si solar cells, due to its low cost and simplicity. As one high efficiency silicon solar cell, amorphous/crystalline silicon heterojunction (SHJ) solar cell has attracted much attention all over the world. The heterojunction interface with very low defects and interface states is critical to the SHJ solar cell performance. In order to obtain high quality interface passivation by depositing a very thin intrinsic amorphous silicon layer on the textured Si conformally, large size pyramidal texture with no metal ion contamination is required. In this work, we utilized tetra-methyl ammonium hydroxide (TMAH) instead of NaOH in the alkaline etching to prepare pyramidal texture on N-type monocrystalline silicon to avoid the possible Na+ contamination. By optimizing the etching conditions, uniform large size pyramidal texture with pyramid size of about 10 μm was fabricated successfully. Furthermore, excellent antireflection performance was demonstrated on such textured Si surface. The average reflectance was lower than 10% in the visible and near infrared spectrum range. Such pyramidally textured Si wafers will be very suitable for SHJ solar cells.

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