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.

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.

Microcrystalline Silicon Thin-Film Solar Cells Prepared at Low Temperature

2001 ◽  
Vol 664 ◽  
Author(s):  
Y. Nasuno ◽  
M. Kondo ◽  
A. Matsuda
Keyword(s):  
Solar Cells ◽  
Low Temperature ◽  
High Efficiency ◽  
Short Circuit ◽  
High Rate ◽  
Rf Plasma ◽  
Microcrystalline Silicon ◽  
Silicon Thin Film ◽  
Low Temperature Deposition ◽  
Temperature Deposition

ABSTRACTHydrogenated microcrystalline silicon (µc-Si:H) p-i-n solar cells have been prepared using a conventional RF plasma-enhanced chemical vapor deposition (PECVD) method at a low process temperature of 140 °C. The low temperature deposition of µc-Si:H has been found to be effective to suppress the formation of oxygen-related donors that cause a reduction in open circuit voltage (Voc) due to shunt leakage. We demonstrate the improvement of Voc by lowering the deposition temperature down to 140, while suppressing the reduction in high short circuit current density (Jsc) and fill factor (FF). A high efficiency of 8.9% was obtained using an Aasahi-U substrate. Furthermore, by optimizing textured structures on ZnO transparent conductive oxide (TCO) substrates, an efficiency of 9.4% (Voc=0.526V, Jsc=25.3mA/cm2, FF=0.710) was obtained. In addition, relatively high efficiency of 8.1% was achieved using VHF (60MHz) plasma at a deposition rate of 12 Å/s. Thus, this low temperature deposition technique for µc-Si:H is promising for both high efficiency and high rate deposition of µc-Si:H solar cells.

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.

17.8%-efficient Amorphous Silicon Heterojunction Solar Cells on p-type Silicon Wafers

2006 ◽  
Vol 910 ◽  
Author(s):  
Qi Wang ◽  
Matt P. Page ◽  
Eugene Iwancizko ◽  
Yueqin Xu ◽  
Yanfa Yan ◽  
...  
Keyword(s):  
Solar Cells ◽  
Solar Cell ◽  
Amorphous Silicon ◽  
High Efficiency ◽  
Short Circuit ◽  
Open Circuit ◽  
Layer Growth ◽  
Surface Recombination Velocity ◽  
Back Contact ◽  
P Type

AbstractWe have achieved an independently-confirmed 17.8% conversion efficiency in a 1-cm2, p-type, float-zone silicon (FZ-Si) based heterojunction solar cell. Both the front emitter and back contact are hydrogenated amorphous silicon (a-Si:H) deposited by hot-wire chemical vapor deposition (HWCVD). This is the highest reported efficiency for a HWCVD silicon heterojunction (SHJ) solar cell. Two main improvements lead to our most recent increases in efficiency: 1) the use of textured Si wafers, and 2) the application of a-Si:H heterojunctions on both sides of the cell. Despite the use of textured c-Si to increase the short-circuit current, we were able to maintain the same 0.65 V open-circuit voltage as on flat c-Si. This is achieved by coating a-Si:H conformally on the c-Si surfaces, including covering the tips of the anisotropically-etched pyramids. A brief atomic H treatment before emitter deposition is not necessary on the textured wafers, though it was helpful in the flat wafers. It is essential to high efficiency SHJ solar cells that the emitter grows abruptly as amorphous silicon, instead of as microcrystalline or epitaxial Si. The contact on each side of the cell comprises a thin (< 5 nm) low substrate temperature (~100°C) intrinsic a-Si:H layer, followed by a doped layer. Our intrinsic layers are deposited at 0.3-1.2 nm/s. The doped emitter and back-contact layers were deposited at a higher temperature (>200°C) and grown from PH3/SiH4/H2 and B2H6/SiH4/H2 doping gas mixtures, respectively. This combination of low (intrinsic) and high (doped layer) growth temperatures was optimized by lifetime and surface recombination velocity measurements. Our rapid efficiency advance suggests that HWCVD may have advantages over plasma-enhanced (PE) CVD in fabrication of high-efficiency heterojunction c-Si cells; there is no need for process optimization to avoid plasma damage to the delicate, high-quality, Si wafers.

Guiding Principle to Develop Intrinsic Microcrystalline Silicon Absorber Layer For Solar Cell By Hot-Wire Cvd

2001 ◽  
Vol 664 ◽  
Author(s):  
A. R. Middya ◽  
U. Weber ◽  
C. Mukherjee ◽  
B. Schroeder
Keyword(s):  
Growth Rate ◽  
Solar Cell ◽  
Cell Structure ◽  
Short Circuit ◽  
Chemical Vapor ◽  
High Growth ◽  
High Growth Rate ◽  
Open Circuit ◽  
Hot Wire ◽  
Microcrystalline Silicon

ABSTRACTWe report on ways to develop device quality microcrystalline silicon (μc-Si:H) intrinsic layer with high growth rate by hot-wire chemical vapor deposition (HWCVD). With combine approach of controlling impurities and moderate H-dilution [H2/SiH4 ͌ 2.5], we developed, for the first time, highly photosensitive (103 μc-Si:Hfilms with high growth rate (>1 nm/s); the microstructure of the film is found to be close to amorphous phase (fc ͌ 46 ̻± 5%). The photosensitivity systematically decreases with fc and saturates to 10 for fc> 70%. On application of these materials in non-optimized pin [.proportional]c-Si:H solar cell structure yields 700 mV open-circuit voltage however, surprisingly low fill factor and short circuit current. The importance of reduction of oxygen impurities [O], adequate passivation of grain boundary (GB) as well as presence of inactive GB of (220) orientation to achieve efficient [.proportional]c-Si:H solar cells are discussed.

Deposition of P-Type Nanocrystalline Silicon Using High Pressure in a VHF-PECVD Single Chamber System

2011 ◽  
Vol 1321 ◽  
Author(s):  
Xiaodan Zhang ◽  
Guanghong Wang ◽  
Xinxia Zheng ◽  
Shengzhi Xu ◽  
Changchun Wei ◽  
...  
Keyword(s):  
High Pressure ◽  
Solar Cells ◽  
Solar Cell ◽  
Conversion Efficiency ◽  
Open Circuit Voltage ◽  
Short Circuit ◽  
Nanocrystalline Silicon ◽  
Open Circuit ◽  
Single Chamber ◽  
P Type

ABSTRACTIn this article, we present a study of boron-doped hydrogenated nanocrystalline silicon (nc-Si: H) films by very high frequency-plasma enhanced chemical vapor deposition (VHF-PECVD) using high deposition pressure. Electrical, structural and optical properties of the films were investigated. Dark conductivity as high as 2.75S/cm of p-type nc-Si: H prepared at 2.5Torr pressure has been achieved at a deposition rate of 1.75Å/s for 25nm thin film. By controlling boron and phosphorus contamination, single junction nc-Si: H solar cells incorporated p-layers prepared under high pressure and low pressure, respectively, were deposited. It has been proven that nanocrystalline silicon solar cells with incorporation of p layer prepared at high pressure has resulted in enhanced open circuit voltage, short circuit current density and subsequently high conversion efficiency. Through the optimization of the bottom solar cell and application of ZnO/Al back reflector, 10.59% initial conversion efficiency of micromorph tandem solar cell (1.027cm2) with an open circuit voltage of 1.3864V, has been fabricated, where the bottom solar cell using a high pressure p layer was deposited in a single chamber.

scholarly journals Numerical Modeling of High Conversion Efficiency Mo/CZTS/CdS/ZnO/ FTO Thin Film – Based Solar Cells

2021 ◽  
Author(s):  
Samer H. Zyoud ◽  
Ahed H. Zyoud ◽  
Naser M. Ahmed ◽  
Anupama R. Prasad ◽  
Sohaib Naseem Khan ◽  
...  
Keyword(s):  
Thin Film ◽  
Numerical Modeling ◽  
Solar Cells ◽  
Solar Cell ◽  
Conversion Efficiency ◽  
High Efficiency ◽  
Short Circuit ◽  
Photovoltaic Cells ◽  
Effect Of Temperature ◽  
Cell Parameters

This article describes in detail the numerical modeling of a CZTS (copper zinc tin sulfide) based kesterite solar cell. The Solar Cell Capacitance Simulator -one-dimension (SCAPS-1D) software was used to simulate MO/CZTS/CdS/ZnO/FTO structured solar cells. The parameters of different photovoltaic thin-film solar cells are estimated and analyzed using numerical modeling. The effects of various parameters on the performance of the photovoltaic cell and the conversion efficiency are discussed. Since the response of the solar cell is also contingent on its internal physical mechanism, J-V characteristic measures are insufficient to characterize the behavior of a device. Different features, as well as different potential conditions, must be considered for simulation, disregarding the belief in the modeling of a solar cell. With a conversion efficiency of 25.72%, a fill factor of 83.75%, a short-circuit current of 32.96436 mA/cm2 and an open-circuit voltage of 0.64V, promising optimized results have been achieved. The findings will be useful in determining the feasibility of fabricating high-efficiency CZTS-based photovoltaic cells. The efficiency of a CZTS-based experimental solar cell is also discussed. First, the effects of experimentally developed CZTS solar cells are simulated in the SCAPS-1D environment. The experimental results are then compared to the SCAPS-1D simulated results. The conversion efficiency of an optimized system increases after cell parameters are optimized. Using one-dimensional SCAPS-1D software, the effect of system parameters such as the thickness, acceptor and donor carrier concentration densities of absorber and electron transport layers, and the effect of temperature on the efficiency of CZTS-based photovoltaic cells is investigated. The proposed results will greatly assist engineers and researchers in determining the best method for optimizing solar cell efficiency, as well as in the development of efficient CZTS-based solar cells.

High-Efficiency HIT Solar Cells for Excellent Power Generating Properties

2008 ◽  
Vol 1123 ◽  
Author(s):  
Toshihiro Kinoshita ◽  
Daisuke Ide ◽  
Yasufumi Tsunomura ◽  
Shigeharu Taira ◽  
Toshiaki Baba ◽  
...  
Keyword(s):  
Solar Cells ◽  
Solar Cell ◽  
Conversion Efficiency ◽  
Production Cost ◽  
High Efficiency ◽  
Open Circuit Voltage ◽  
Short Circuit ◽  
Open Circuit ◽  
Surface Recombination Velocity ◽  
Dominant Factor

AbstractIn order to achieve the widespread use of HIT (Hetero-junction with I etero-Intrinsic T ntrinsic Thin-layer) solar cells, it is important to reduce the power generating cost. There are three main approaches for reducing this cost: raising the conversion efficiency of the HIT cell, using a thinner wafer to reduce the wafer cost, and raising the open circuit voltage to obtain a better temperature coefficient. With the first approach, we have achieved the highest conversion efficiency values of 22.3%, confirmed by AIST, in a HIT solar cell. This cell has an open circuit voltage of 0.725 V, a short circuit current density of 38.9 mA/cm2 and a fill factor of 0.791, with a cell size of 100.5 cm2. The second approach is to use thinner Si wafers. The shortage of Si feedstock and the strong requirement of a lower sales price make it necessary for solar cell manufacturers to reduce their production cost. The wafer cost is an especially dominant factor in the production cost. In order to provide low-priced, high-quality solar cells, we are trying to use thinner wafers. We obtained a conversion efficiency of 21.4% (measured by Sanyo) for a HIT solar cell with a thickness of 85μm. Even better, there was absolutely no sagging in our HIT solar cell because of its symmetrical structure. The third approach is to raise the open circuit voltage. We obtained a remarkably higher Voc of 0.739 V with the thinner cell mentioned above because of its low surface recombination velocity. The high Voc results in good temperature properties, which allow it to generate a large amount of electricity at high temperatures.

High Efficiency Thin Film Solar Cells with Intrinsic Microcrystalline Silicon Prepared by Hot Wire CVD

2002 ◽  
Vol 715 ◽  
Author(s):  
S. Klein ◽  
F. Finger ◽  
R. Carius ◽  
B. Rech ◽  
L. Houben ◽  
...  
Keyword(s):  
Thin Film ◽  
Solar Cells ◽  
High Efficiency ◽  
Short Circuit ◽  
Wavelength Region ◽  
Maximum Efficiency ◽  
Hot Wire ◽  
Microcrystalline Silicon ◽  
Cell Parameters ◽  
Volume Fractions

AbstractThin film microcrystalline silicon solar cells were prepared with intrinsic absorber layers by Hot Wire CVD at various silane concentrations and substrate temperatures. Independently from the substrate temperature, a maximum efficiency is observed close to the transition to amorphous growth, i.e. the best cells already show considerable amorphous volume fractions. A detailed analysis of the thickness dependence of the solar cell parameters in the dark and under illumination indicate a high electronic quality of the i-layer material. Solar cells with very high open circuit voltages Voc up to 600mV in combination with fill factors above 70% and high short circuit current densities jsc of 22mA/cm2 were obtained, yielding efficiencies above 9%. The highest efficiency of 9.4% was achieved in solar cells of 1.4μm and 1.8μm thickness. These cells with high Voc have considerable amorphous volume fractions in the i-layer, leading to a reduced absorption in the infrared wavelength region.

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