Microcrystalline silicon solar cells prepared by 13.56 MHz PECVD at high growth rates: Solar cell and material properties

2001 ◽  
Vol 664 ◽  
Author(s):  
Tobias Roschek ◽  
Bernd Rech ◽  
Wolfhard Beyer ◽  
Peter Werner ◽  
Felix Edelman ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Solar Cells ◽  
Solar Cell ◽  
Volume Fraction ◽  
Chemical Vapour ◽  
High Growth ◽  
Microcrystalline Silicon ◽  
Deposition Parameters ◽  
Wide Range ◽  
Low Efficiency

ABSTRACTMicrocrystalline silicon (μc-Si:H) solar cells were prepared in a wide range of deposition parameters using 13.56 MHz plasma-enhanced chemical vapour deposition (PECVD). The best μc-Si:H solar cells were prepared close to the transition to amorphous silicon (a-Si:H) growth at very high deposition pressures (∼10 Torr) showing solar cell efficiencies up to 8.0 % at a deposition rate of 5ÊÅ/s. Investigations of the solar cells were performed by Raman spectroscopy and transmission electron microscopy (TEM). TEM measurements revealed similar structural properties with similar high crystalline volume fractions for these cells although they showed distinctly different efficiencies. However, an increased amorphous volume fraction was detected by Raman spectroscopy for the low efficiency cells prepared at low deposition pressures. This result is attributed to an increased ion bombardment at low pressures.

Microcrystalline Silicon for Solar Cells at High Deposition Rates by Hot Wire Cvd

2002 ◽  
Vol 715 ◽  
Author(s):  
R. E. I. Schropp ◽  
Y. Xu ◽  
E. Iwaniczko ◽  
G. A. Zaharias ◽  
A. H. Mahan
Keyword(s):  
Solar Cells ◽  
Substrate Temperature ◽  
Volume Fraction ◽  
Silicon Layer ◽  
Hot Wire ◽  
Crystalline Volume Fraction ◽  
Microcrystalline Silicon ◽  
Deposition Rates ◽  
Deposition Parameters ◽  
Si Films

AbstractWe have explored which deposition parameters in Hot Wire CVD have the largest impact on the quality of microcrystalline silicon (μc-Si) made at deposition rates (Rd) < 10 Å/s for use in thin film solar cells. Among all parameters, the filament temperature (Tfil) appears to be crucial for making device quality films. Using two filaments and a filament-substrate spacing of 3.2 cm, μc-Si films, using seed layers, can be deposited at high Tfil (∼2000°C) with a crystalline volume fraction < 70-80 % at Rd's < 30 Å/s. Although the photoresponse of these layers is high (< 100), they appear not to be suitable for incorporation into solar cells, due to their porous nature. n-i-p cells fabricated on stainless steel with these i-layers suffer from large resistive effects or barriers, most likely due to the oxidation of interconnected pores in the silicon layer. The porosity is evident from FTIR measurements showing a large oxygen concentration at ∼1050 cm-1, and is correlated with the 2100 cm-1 signature of most of the Si-H stretching bonds. Using a Tfil of 1750°C, however, the films are more compact, as seen from the absence of the 2100 cm-1 SiH mode and the disappearance of the FTIR Si-O signal, while the high crystalline volume fraction (< 70-80 %) is maintained. Using this Tfil and a substrate temperature of 400°C, we obtain an efficiency of 4.9 % for cells with a Ag/ZnO back reflector, with an i-layer thickness of only ∼0.7 μm. High values for the quantum efficiency extend to very long wavelengths, with values of 33 % at 800 nm and 15 % at 900 nm, which are unequalled by a-SiGe:H alloys. Further, by varying the substrate temperature to enable deposition near the microcrystalline to amorphous transition (‘edge’) and incorporating variations in H2 dilution during deposition of the bulk, efficiencies of 6.0 % have been obtained. The Rd's of these i-layers are 8-10 Å/s, and are the highest to date obtained with HWCVD for microcrystalline layers used in cells with efficiencies of ∼6 %.

scholarly journals Efficiency enhancement of CZTSSe solar cells via screening the absorber layer by examining of different possible defects

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Mehran Minbashi ◽  
Arash Ghobadi ◽  
Elnaz Yazdani ◽  
Amirhossein Ahmadkhan Kordbacheh ◽  
Ali Hajjiah
Keyword(s):  
Solar Cells ◽  
Solar Cell ◽  
Valence Band Maximum ◽  
Absorber Layer ◽  
Cell Performance ◽  
Secondary Phases ◽  
Cell Efficiency ◽  
Wide Range ◽  
Low Efficiency ◽  
Defect Densities

AbstractThis study represents the investigation of earth-abundant and non-toxic CZTSSe absorber materials in kesterite solar cell by using the Finite Element Method (FEM) with (1) electrical, and (2) optical approaches. The simulated results have been validated with the experimental results to define guidelines for boosting the cell performance. For improving the cell efficiency, potential barrier variations in the front contact, and the effect of different lattice defects in the CZTSSe absorber layer have been examined. Controlling the defects and the secondary phases of absorber layer have significant influence on the cell performance improvement. Previous studies have demonstrated that, synthesis of CZTSSe:Na nanocrystals and controlling the S/(S + Se), Cu/(Zn + Sn), and Zn/Sn ratios (stoichiometry) have significant effects on the reduction of trap-assisted recombination (Shockley–Read–Hall recombination model). In this work, a screening-based approach has been employed to study the cell efficiency over a wide range of defect densities. Two categorized defect types including benign defects ($${N}_{t}<{10}^{16}$$ N t < 10 16 cm−3 , Nt defines trap density) and harmful defects $${(N}_{t}>{10}^{16}$$ ( N t > 10 16 cm−3) in the absorber bandgap in the CZTSSe solar cell, by analyzing their position changes with respect to the electron Fermi level (Efn) and the Valence Band Maximum positions have been identified. It is realized that, the harmful defects are the dominant reason for the low efficiency of the kesterite solar cells, therefore, reducing the number of harmful defects and also total defect densities lead to the power conversion efficiency record of 19.06%. This increment makes the CZTSSe solar cells as a promising candidate for industrial and commercial applications.

scholarly journals Material and solar cell research in high efficiency micromorph tandem solar cell

2015 ◽  
Vol 37 ◽  
pp. 434 ◽  
Author(s):  
Razagh Hafezi ◽  
Soroush Karimi ◽  
Sharie Jamalzae ◽  
Masoud Jabbari
Keyword(s):  
Thin Film ◽  
Solar Cells ◽  
Solar Cell ◽  
Amorphous Silicon ◽  
High Efficiency ◽  
Crystalline Silicon ◽  
Chemical Vapour ◽  
Microcrystalline Silicon ◽  
Tandem Solar Cells ◽  
Bottom Cell

“Micromorph” tandem solar cells consisting of a microcrystalline silicon bottom cell and an amorphous silicon top cell are considered as one of the most promising new thin-film silicon solar-cell concepts. Their promise lies in the hope of simultaneously achieving high conversion efficiencies at relatively low manufacturing costs. The concept was introduced by IMT Neuchâtel, based on the VHF-GD (very high frequency glow discharge) deposition method. The key element of the micromorph cell is the hydrogenated microcrystalline silicon bottom cell that opens new perspectives for low-temperature thin-film crystalline silicon technology. This paper describes the use, within p–i–n- and n–i–p-type solar cells, of hydrogenated amorphous silicon (a-Si:H) and hydrogenated microcrystalline silicon (_c-Si:H) thin films (layers), both deposited at low temperatures (200_C) by plasma-assisted chemical vapour deposition (PECVD), from a mixture of silane and hydrogen. Optical and electrical properties of the i-layers are described. Finally, present performances and future perspectives for a high efficiency ‘micromorph’ (mc-Si:Hya-Si:H) tandem solar cells are discussed.

Microstructure Evolution with Thickness and Hydrogen Dilution Profile in Microcrystalline Silicon Solar Cells

2004 ◽  
Vol 808 ◽  
Author(s):  
Baojie Yan ◽  
Guozhen Yue ◽  
Jeffrey Yang ◽  
Subhendu Guha ◽  
D. L. Williamson ◽  
...  
Keyword(s):  
Solar Cells ◽  
Solar Cell ◽  
Microstructure Evolution ◽  
Volume Fraction ◽  
Microcrystalline Silicon ◽  
Very High Frequency ◽  
Area Efficiency ◽  
Junction Solar Cell ◽  
Hydrogen Dilution ◽  
Back Reflectors

ABSTRACTHydrogenated microcrystalline silicon (m c-Si:H) solar cells with different thicknesses were deposited on specular stainless steel substrates and on textured Ag/ZnO back reflectors using RF and modified very high frequency glow discharge at various deposition rates. Raman spectra and X-ray diffraction patterns exhibit a significant increase of microcrystalline volume fraction and in grain size with film thickness. Atomic force microscopy reveals an increase in the size of microstructural features and the surface roughness with increasing thickness. Based on these results, we believe that the increase of the microcrystalline phase with thickness is the main reason for the deterioration of cell performance with the thickness of the intrinsic layer. To overcome this problem, we have developed a procedure of varying the hydrogen dilution ratio during deposition. Using this method, we have been successful in controlling the microstructure evolution and achieved an initial active-area efficiency of 8.4% for a c-Si:H single-junction solar cell, and 13.6% for an a-Si:H/a-SiGe:H/m c-Si:H triple-junction solar cell.

High Rate Deposition of Microcrystalline Silicon Solar Cells Using 13.56 MHz PECVD – Prerequisites and Limiting Factors

2002 ◽  
Vol 715 ◽  
Author(s):  
Tobias Roschek ◽  
Tobias Repmann ◽  
Oliver Kluth ◽  
Joachim Müller ◽  
Bernd Rech ◽  
...  
Keyword(s):  
Solar Cells ◽  
Plasma Deposition ◽  
Chemical Vapor ◽  
High Rate ◽  
Limiting Factors ◽  
Pulsed Plasma ◽  
Microcrystalline Silicon ◽  
Electrode Distance ◽  
Deposition Parameters ◽  
Wide Range

AbstractMicrocrystalline silicon (μìc-Si:H) solar cells were prepared in a wide range of deposition parameters using high pressure 13.56 MHz plasma-enhanced chemical vapor deposition (PECVD). Focus was on the influence of deposition pressure, electrode distance and the application of a pulsed plasma on high rate deposition of solar cells. At electrode distances between 5 and 20 mm solar cells with efficiencies >8 % were prepared. A medium electrode distance of 10 mm yielded best device performance. Pulsed plasma deposition leads to good results at medium deposition rates of ∼5 Å/s, for higher rates a strong decrease of efficiency was observed. The highest efficiencies in a small area reactor were 8.9 % for CW and 8.4 % for pulsed plasma. We also succeeded in preparing μc-Si:H and a-Si:H/μc-Si:H solar cells in a 30x30 cm2 reactor with efficiencies of 9 % and 12.5 %, respectively.

scholarly journals Grown Low-Temperature Microcrystalline Silicon Thin Film by VHF PECVD for Thin Films Solar Cell

2015 ◽  
Vol 2015 ◽  
pp. 1-5 ◽  
Author(s):  
Shanglong Peng ◽  
Desheng Wang ◽  
Fuhua Yang ◽  
Zhanguo Wang ◽  
Fei Ma
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Solar Cells ◽  
Solar Cell ◽  
Short Circuit ◽  
High Growth ◽  
Microcrystalline Silicon ◽  
Silicon Thin Film ◽  
Very High Frequency ◽  
Silicon Thin Films

Hydrogenated microcrystalline silicon thin films can be used to fabricate stable thin film solar cell, which were deposited by very high frequency plasma-enhanced chemical vapor deposition at low temperatures (~200°C). It has been found that the obtained film presented excellent structural and electrical properties, such as high growth rate and good crystallinity. With the decreasing of silane concentration, the optical gap and the dark conductivity increased, whereas the activation energy decreased. A reasonable explanation was presented to elucidate these phenomena. In addition, we fabricated p-i-n structure solar cells using the optimum microcrystalline silicon thin films, and preliminary efficiency of 4.6% was obtained for 1 μm thick microcrystalline silicon thin film solar cells with open-circuits voltage of 0.773 V and short-circuits current density of 12.28 mA/cm2. Future scope for performance improvement lies mainly in further increasing the short-circuit current.

Transport Path in Hydrogenated Microcrystalline Silicon

2002 ◽  
Vol 715 ◽  
Author(s):  
N. Wyrsch ◽  
C. Droz ◽  
L. Feitknecht ◽  
J. Spitznagel ◽  
A. Shah
Keyword(s):  
Raman Spectroscopy ◽  
Volume Fraction ◽  
Conductivity Measurement ◽  
Dark Conductivity ◽  
Transition Regime ◽  
Conductivity Data ◽  
Crystalline Volume Fraction ◽  
Microcrystalline Silicon ◽  
Crystalline Fraction ◽  
Transport Path

AbstractUndoped microcrystalline silicon samples deposited in the transition regime between amorphous and microcrystalline growth have been investigated by dark conductivity measurement and Raman spectroscopy. From the latter, a semi-quantitative crystalline volume fraction Xc of the sample was deduced and correlated with dark conductivity data in order to reveal possible percolation controlled transport. No threshold was observed around the critical crystalline fraction value Xc of 33%, as reported previously, but a threshold in conductivity data was found at Xc≈50%. This threshold is interpreted here speculatively as being the result of postoxidation, and not constituting an actual percolation threshold.

High Haze and Low Resistive MgO/AZO Bi-layer Transparent Conducting Oxide for Thin Film Solar Cells

2011 ◽  
Vol 1327 ◽  
Author(s):  
Dong Won Kang ◽  
Jong Seok Woo ◽  
Sung Hwan Choi ◽  
Seung Yoon Lee ◽  
Heon Min. Lee ◽  
...  
Keyword(s):  
Thin Film ◽  
Solar Cells ◽  
Solar Cell ◽  
Silicon Solar Cell ◽  
Transparent Conducting Oxide ◽  
Visible Region ◽  
Xrd Analysis ◽  
Thin Film Solar Cells ◽  
Microcrystalline Silicon ◽  
Transparent Conducting

ABSTRACTWe have propsed MgO/AZO bi-layer transparent conducting oxide (TCO) for thin film solar cells. From XRD analysis, it was observed that the full width at half maximum of AZO decreased when it was grown on MgO precursor. The Hall mobility of MgO/AZO bi-layer was 17.5cm2/Vs, whereas that of AZO was 20.8cm2/Vs. These indicated that the crystallinity of AZO decreased by employing MgO precursor. However, the haze (=total diffusive transmittance/total transmittance) characteristics of highly crystalline AZO was significantly improved by MgO precursor. The average haze in the visible region increased from 14.3 to 48.2%, and that in the NIR region increased from 6.3 to 18.9%. The reflectance of microcrystalline silicon solar cell was decreased and external quantum efficiency was significantly improved by applying MgO/AZO bi-layer TCO. The efficiency of microcrystalline silicon solar cell with MgO/AZO bi-layer front TCO was 6.66%, whereas the efficiency of one with AZO single TCO was 5.19%.

Model-based Quantitative Assessment of Crystallinity and Parasitic Absorption in Microcrystalline Silicon Solar Cells

2012 ◽  
Vol 1426 ◽  
pp. 383-387
Author(s):  
Thomas Lanz ◽  
Corsin Battaglia ◽  
Christophe Ballif ◽  
Beat Ruhstaller
Keyword(s):  
Solar Cells ◽  
Solar Cell ◽  
Light Scattering ◽  
Quantum Efficiency ◽  
External Quantum Efficiency ◽  
Quantitative Assessment ◽  
Silicon Solar Cells ◽  
Normalization Procedure ◽  
Microcrystalline Silicon ◽  
Scattering Model

ABSTRACTWe investigate the influence of the crystallinity of the absorber layer and parasitic absorption in the doped layers and electrodes on the external quantum efficiency and reflection of microcrystalline silicon (μc-Si:H) solar cells. Using an optical light scattering model we systematically study variations in the crystallinity and validate a simple normalization procedure that allows assessing the gains that can be achieved by reducing the parasitic absorption. The optimization potential is demonstrated with solar cell samples with increased crystallinity and eliminated parasitic absorption.

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.

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