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Optimization of Recombination Layer in the Tunnel Junction of Amorphous Silicon Thin-Film Tandem Solar Cells  [PDF]
Yang-Shin Lin,Shui-Yang Lien,Chao-Chun Wang,Chia-Hsun Hsu,Chih-Hsiang Yang,Asheesh Nautiyal,Dong-Sing Wuu,Pi-Chuen Tsai,Shuo-Jen Lee
International Journal of Photoenergy , 2011, DOI: 10.1155/2011/264709
Abstract: The amorphous silicon/amorphous silicon (a-Si/a-Si) tandem solar cells have attracted much attention in recent years, due to the high efficiency and low manufacturing cost compared to the single-junction a-Si solar cells. In this paper, the tandem cells are fabricated by high-frequency plasma-enhanced chemical vapor deposition (HF-PECVD) at 27.1?MHz. The effects of the recombination layer and the i-layer thickness matching on the cell performance have been investigated. The results show that the tandem cell with a p+ recombination layer and i2/i1 thickness ratio of 6 exhibits a maximum efficiency of 9.0% with the open-circuit voltage ( ) of 1.59?V, short-circuit current density ( ) of 7.96?mA/cm2, and a fill factor (FF) of 0.70. After light-soaking test, our a-Si/a-Si tandem cell with p+ recombination layer shows the excellent stability and the stabilized efficiency of 8.7%. 1. Introduction Amorphous silicon (a-Si)/a-Si tandem solar cells have attracted extensive interest among solar cell because of the less light-induced degradation [1, 2] (Stabler-Wronski effect) compared to their single-junction solar cell counterparts. The n-p junction between the two subcells is often referred to as a tunnel junction but actually functions as a recombination junction in electrically connecting the two p-i-n junctions of the tandem structure. For high stabilized efficiency tandem cell applications, a good n/p junction must have very high recombination rates, negligible optical absorption, and an ohmic characteristic with a low series resistance in order to improve the carrier transport [3–6]. Various recombination layers, such as a-SiC:H [7], metal oxides [8], microcrystalline layer [9], and / recombination layer [10] have been introduced between the n and p layers to promote carrier recombination. The thickness of intrinsic- (i-) layer of individual subcell is another key parameter because of the current matching limitation imposed by series connection. In addition, reducing the i-layer thickness of top cell as possible as it is important to stabilize against light degradation [11, 12]. In this paper, we use a recombination layer as the recombination layer inserted in a tandem solar cell to investigate the effect on the cell performance. Furthermore, the tandem cells with different i-layer thickness matching ratio are also fabricated and their photovoltaic characteristics are also discussed. 2. Experimental In this study, we prepared double-junction (a-Si/a-Si) solar cells by high-frequency (27.1?MHz) plasma-enhanced chemical vapor deposition (HF-PECVD). The
Fabrication of Thin-Film LAPS with Amorphous Silicon  [PDF]
Tatsuo Yoshinobu,Michael J. Sch?ning,Friedhelm Finger,Werner Moritz,Hiroshi Iwasaki
Sensors , 2004, DOI: 10.3390/s41000163
Abstract: To improve the spatial resolution of the light-addressable potentiometric sensor (LAPS), it is necessary to reduce the thickness of the semiconductor layer, which, however, causes a problem of the mechanical strength of the sensor plate. In this study, a thin-film LAPS was fabricated with amorphous silicon (a-Si) deposited on a transparent glass substrate. The current-voltage characteristics and pH sensitivity of the fabricated a-Si LAPS were investigated.
Role of amorphous silicon domains on Er3+ emission in the Er-doped hydrogenated amorphous silicon suboxide film
Role of amorphous silicon domains of Er^3+ emission in the Er—doped hydrogenated amorphous silicon suboxide film

Chen Chang-Yong,Chen Wei-De,Li Guo-Hu,Song Shu-Fang,Ding Kun,Xu Zhen-Jia,
陈长勇
,陈维德,李国华,宋淑芳,丁琨,许振嘉

中国物理 B , 2003,
Abstract: An investigation on the correlation between amorphous Si (a-Si) domains and Er^{3+} emission in the Er-doped hydrogenated amorphous silicon suboxide (a-Si:O:H) film is presented. On one hand, a-Si domains provide sufficient carriers for Er^{3+} carrier-mediated excitation which has been proved to be the highest excitation path for Er^{3+} ion; on the other hand, hydrogen diffusion from a-Si domains to amorphous silicon oxide (a-SiO_x) matrix during annealing has been found and this possibly decreases the number of nonradiative centres around Er^{3+} ions. This study provides a better understanding of the role of a-Si domains on Er^{3+} emission in a-Si:O:H films.
Silicon Thin-Film Solar Cells  [PDF]
Guy Beaucarne
Advances in OptoElectronics , 2007, DOI: 10.1155/2007/36970
Abstract: We review the field of thin-film silicon solar cells with an active layer thickness of a few micrometers. These technologies can potentially lead to low cost through lower material costs than conventional modules, but do not suffer from some critical drawbacks of other thin-film technologies, such as limited supply of basic materials or toxicity of the components. Amorphous Si technology is the oldest and best established thin-film silicon technology. Amorphous silicon is deposited at low temperature with plasma-enhanced chemical vapor deposition (PECVD). In spite of the fundamental limitation of this material due to its disorder and metastability, the technology is now gaining industrial momentum thanks to the entry of equipment manufacturers with experience with large-area PECVD. Microcrystalline Si (also called nanocrystalline Si) is a material with crystallites in the nanometer range in an amorphous matrix, and which contains less defects than amorphous silicon. Its lower bandgap makes it particularly appropriate as active material for the bottom cell in tandem and triple junction devices. The combination of an amorphous silicon top cell and a microcrystalline bottom cell has yielded promising results, but much work is needed to implement it on large-area and to limit light-induced degradation. Finally thin-film polysilicon solar cells, with grain size in the micrometer range, has recently emerged as an alternative photovoltaic technology. The layers have a grain size ranging from 1 μm to several tens of microns, and are formed at a temperature ranging from 600 to more than 1000∘C. Solid Phase Crystallization has yielded the best results so far but there has recently been fast progress with seed layer approaches, particularly those using the aluminum-induced crystallization technique.
Low Cost Amorphous Silicon Intrinsic Layer for Thin-Film Tandem Solar Cells  [PDF]
Ching-In Wu,Shoou-Jinn Chang,Kin-Tak Lam,Shuguang Li,Sheng-Po Chang
International Journal of Photoenergy , 2013, DOI: 10.1155/2013/183626
Abstract: The authors propose a methodology to improve both the deposition rate and SiH4 consumption during the deposition of the amorphous silicon intrinsic layer of the a-Si/μc-Si tandem solar cells prepared on Gen 5 glass substrate. It was found that the most important issue is to find out the saturation point of deposition rate which guarantees saturated utilization of the sourcing gas. It was also found that amorphous silicon intrinsic layers with the same value will result in the same degradation of the fabricated modules. Furthermore, it was found that we could significantly reduce the production cost of the a-Si/μc-Si tandem solar cells prepared on Gen 5 glass substrate by fine-tuning the process parameters. 1. Introduction In recent years, silicon-based thin-film solar cells have been studied extensively due to their potential benefits in low cost, high efficiency, and low pollution during production. It has been shown that these silicon-based thin-film solar cells are scalable for full-sized commercial production [1]. However, the fundamental challenge of silicon thin-film solar cells is light-induced degradation known as the Staebler-Wronski Effect (SWE) [2]. There are currently two major types of silicon thin-film solar cells in the market. One is the amorphous silicon (a-Si) only module, which could achieve an approximately 7% energy conversion efficiency with a degradation ratio of around 23%. The other is the amorphous silicon tandem microcrystalline silicon (a-Si/μc-Si) tandem device, which could achieve more than 10% energy conversion efficiency with a smaller degradation ratio of around 15%. It is generally believed that increasing the ratio of hydrogen gas in the process of forming the intrinsic layers could improve the module stability. However, increasing hydrogen dilution ratio during the formation of the intrinsic layers suffers from two major drawbacks. First, hydrogen treatment could easily compromise p-layer interface in front of the intrinsic layer. Second, increasing the hydrogen dilution ratio of the total process gas also means decreasing the ratio of SiH4 used for forming the silicon film. This could result in a reduction in deposition rate. It has been reported previously that one can tune the distance of the electrodes to increase both the utilization of the depositing gas and the deposition rate [3]. However, it is necessary to adjust the hardware of the deposition system which depends strongly on the system used. It has also been reported that one can introduce triode to control the dissociation of reacting gas and the
Use prospects in microelectronics for polycrystalline silicon film structures with p–n junction  [cached]
Raimjon Aliev,Erkin Mutarov
Perspectives of Innovations, Economics and Business , 2009,
Abstract: The paper discusses perspectives of elaborating microelectronic and optoelectronic devices on polycrystalline silicon films. The I-V features of structures with p-n-junction, formed by using methods of р-type conductivity layer grow, thermal diffusion and ion-implantation of boron atoms into n-type polycrystalline silicon layer are compared. The I-V feature with S-form curve of the investigated structures conditioned by changing of the conductivities of base and grain boundaries under thermal processing are revealed.
Absorption enhancement in amorphous silicon photonic crystals for thin film photovoltaic solar cells  [PDF]
Ounsi El Daif,Emmanuel Drouard,Yeonsang Park,Alain Fave,Anne Kaminski,Mustapha Lemiti,Xavier Letartre,Pierre Viktorovitch,Sungmo Ahn,Heonsu Jeon,Christian Seassal
Physics , 2009,
Abstract: We report on very high enhancement of thin layer's absorption through band-engineering of a photonic crystal structure. We realized amorphous silicon (aSi) photonic crystals, where slow light modes improve absorption efficiency. We show through simulation that an increase of the absorption by a factor of 1.5 is expected for a film of aSi. The proposal is then validated by an experimental demonstration, showing an important increase of the absorption of a layer of aSi over a spectral range of 0.32-0.76 microns.
Thin Film Silicon-On-Insulator of Bipolar Junction Transistor: Process Fabrication and characterization Technology
Osama S Hammad,Othman Sidek,,Kamarul Azizi Ibrahim
International Journal of Engineering Science and Technology , 2010,
Abstract: The great success of semiconductor industry has been driven by the advancement in transistor technology in its early era. The industry could improve the performance of their products by shrinking the transistor dimensions and integrating more transistors. However, this strategy is becoming less effective, as the transistors demandedsubstantial interconnections between them, and the speed of integrated circuit products are being dominated by interconnections. Innovations are necessary in the interconnection technology to overcome the barriers. Furthermore, fabrication thin-film silicon on insulator of bipolar junction transistor (TFSOI-BJT) is the subject ofthis paper. More specifically, we have worked in two domains: the main part of the work was to fabricate Bipolar Junction Transistor On Silicon on Insulator. While the second part was the technological solid source diffusion which is PhosphPlus/BoronPlus of a process to manufacture base and emitter transistor. This paper focuses onselective solid source diffusion of in-situ PhosphorusPlus/BoronPlus doped silicon on insulator (SOI) alloys intended for this application. Experiments were carried out to study electrical properties of the in-situ doped layers with emphasis on maximizing the active carrier concentration. Active phosphorus and boron levels were obtained. The diffusion layers were used to fabricate two pn junctions back to back. Junctions were fabricated to create heavily doped region suffered from band to band tunneling, which is expected regardless of the junction formation technique. While in, Junctions fabricated to create lightly doped region exhibited behavior equivalent to best junctions.
Study of Amorphous Silicon Thin-film Solar Cells
非晶硅薄膜太阳能电池特性研究

WANG Zhen-wen,FU Chao-xue,WU Guo-sheng,LIU Shu-ping,
王振文
,付朝雪,吴国盛,刘淑平

红外 , 2012,
Abstract: The operation principles of solar cells are presented and their physical models are given. An indoor experiment for measuring the output characteristics of amorphous silicon thin-film cells is designed and the experimental result is analyzed. A small separate photovoltaic (PV) power generation system is built. Its engineering structure is given. The experimental result shows that the conversion efficiency of the solar cells is consistent with the result measured in laboratory. The system is proved to be reliable and high efficient.
An investigation of optimal interfacial film condition for Cu-Mn alloy based source/drain electrodes in hydrogenated amorphous silicon thin film transistors
Haruhiko Asanuma,Takaaki Suzuki,Toshiaki Kusunoki
AIP Advances , 2012, DOI: 10.1063/1.4727939
Abstract: To aid in developing next generation Cu-Mn alloy based source/drain interconnects for thin film transistor liquid crystal displays (TFT-LCDs), we have investigated the optimal structure of a pre-formed oxide layer on phosphorus doped hydrogenated amorphous silicon (n+a-Si:H) that does not degrade TFT electrical properties. We use transmission electron microscopy (TEM) and electron energy loss spectroscopy (EELS) to examine composition depth profiles of and structural information for the Cu-Mn alloy/n+a-Si:H interface region. In aiming to achieve the same electrical properties as those of TFTs having conventional Mo source/drain electrodes, we have obtained three important findings: (1) in typical TFT-LCD manufacturing processes, no Mn complex oxide layer is formed because Mn cannot diffuse substantially into an n+a-Si:H surface during low temperature (below 300°C) processes and the growth of Mn complex oxide layer would also be limited by the absence of excess oxygen species; (2) a pre-formed silicon oxide layer much thicker than 1 nm severely degrades TFT electrical properties and therefore an ultrathin (≈1 nm) silicon oxide layer is required to prevent the degradation; (3) Cu diffuses into an n+a-Si:H layer at oxygen-deficient spots and thus uniform surface oxidation is required to prevent the diffusion.
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