Incoherent-light induced diffusion of phosphorus as a doping procedure for low-cost silicon solar cells (original) (raw)
Related papers
Materials Research Express, 2019
In this study, the impact of diffusion time on monocrystalline silicon solar cell has been analysed morphologically, elementally, and electrically by adjusting diffusion time to establish optimized properties for high-efficiency. P-type raw wafers were prepared for diffusion following cleaning and wet etching operation. POCl 3 diffusion was done by varying diffusion time with a constant flow rate of process gases. The morphological and elemental studies were carried out with scanning electron microscope (SEM), and energy dispersive x-ray spectroscopy (EDX) respectively. Four-point probe test and Hall Effect measurement were used for studying the electrical characteristics (sheet resistance, resistivity, conductivity, and bulk concentration). From SEM result analysis, noticeable structural damages were found with the increase of doping time. Surface reflectance measurement (SRM) also supported the morphological distortion. Phosphorus, oxygen, silicon, and boron were traced by EDX analysis. The formation of phosphosilicate glass (PSG), as well as the depth of emitter, has been confirmed from the elemental analysis. The emitter length was varied from 2.5 μm to 9 μm. 5 min doped sample showed minimum surface deformation with maximum light absorbance. An acceptable sheet resistance with a compatible conductivity, mobility, and bulk concentration are also found for 5 min diffusion, which could potentially lead to high-efficient solar cell fabrication.
THE PRODUCTION OF SOLAR CELLS FROM MONOCRYSTALLINE SILICON BY PHOSPHORUS DIFFUSION
This article outlines the materials and methods used to fabricate monocrystalline silicon solar cells. The purpose of this research is to study solar cell production technology and solar cell monocrystalline silicon production technology locally. We use several processing steps to obtain the final result of the solar cell. First, a square single crystal silicon wafer with a size of 150×150 mm 2 and a thickness of 200 μm is prepared. m, it is a oriented Cheklaussky (100) silicon wafer. The cleaning and texturing of the wafer are performed using various chemical solutions, and the edge of the wafer is isolated with an edge release paste. The phosphor is diffused in a diffusion furnace, a pn junction is formed with phosphorous oxychloride (POCl 3) liquid, and the front and back sides are respectively metalized by screen printing with silver and aluminum pastes. The plate is then subjected to rapid thermal annealing at the high temperature of the contact hardening zone. Finally, the LIV tester was used to characterize the solar cells produced. The data shows that the maximum power is 10.3369 W, and the maximum voltage power is 027504 V, full power current-37.5833 mA, open circuit voltage-0.555462 V, short-circuit current-56.5867 mA, fill factor-32.8868, battery efficiency-about 7%. Since Monocisralin solar cells are manufactured in India for the first time, the output of solar cells we produce is very low. The India Atomic Energy Commission (BAEC) has established a laboratory for the local production of solar cells. The processing technology, equipment temperature and the quality of air, water and other chemicals need to be optimized. To improve the efficiency of solar cells.
International Journal of Photoenergy, 2014
We demonstrate the performance improvement of p-type single-crystalline silicon (sc-Si) solar cells resulting from front surface passivation by a thin amorphous silicon (a-Si) film deposited prior to phosphorus diffusion. The conversion efficiency was improved for the sample with an a-Si film of ~5 nm thickness deposited on the front surface prior to high-temperature phosphorus diffusion, with respect to the samples with an a-Si film deposited on the front surface after phosphorus diffusion. The improvement in conversion efficiency is 0.4% absolute with respect to a-Si film passivated cells, that is, the cells with an a-Si film deposited on the front surface after phosphorus diffusion. The new technique provided a 0.5% improvement in conversion efficiency compared to the cells without a-Si passivation. Such performance improvements result from reduced surface recombination as well as lowered contact resistance, the latter of which induces a high fill factor of the solar cell.
Fabrication of Monocrystalline Silicon Solar Cell using Phosphorous Diffusion Technique
This paper gives an overview of the materials and methods used for fabricating a monocrystalline silicon solar cell. The aim of this research is to study the solar cell fabrication technology and fabrication of monocrystalline silicon solar using phosphorous diffusion technique locally. For solar cell fabrication we have used several number of processing steps to get the final solar cell output. At first we took a p-type monocrystalline silicon wafer with square shape 150×150 mm2 in size, 200µm in thickness and which is a (100) oriented Czochralski Si wafer. Then Cleaning and texturing of the wafer was done using different chemical solutions and edge isolation of wafer was done using edge isolation paste. Phosphorous diffusion was done by diffusion furnace to form p-n junction using liquid Phosphorus Oxychloride (POCl3). Front and back side metallization was done by screen printers using silver paste and aluminum paste respectively. Then Rapid Thermal Annealing of the wafer was done at high zone temperature for curing the contact. Finally, fabricated solar cell was characterized by LIV tester.
IEEE Transactions on Electron Devices, 2000
ABSTRACT In this paper, we have presented the experimental results of phosphorus diffusion in silicon for the cases of rapid thermal processing (RTP) and rapid photothermal processing (RPP). In the case of the RPP, other than thermal energy, the vacuum ultraviolet photons are used as an additional source of energy. We have investigated the secondary-ion-mass-spectroscopy impurity profiles at different concentrations of P in Si. Based on our own experimental results and the data published in the open literature, we have provided an explanation of the enhanced diffusion both for the RTP and RPP cases. The thermal factor leads to the excitation (vibration) of atoms and quantum energy to the electron system excitation. As compared with the pure thermal process, the quantum-energy contribution provides a reduced activation energy and a higher diffusion coefficient.
International Journal of Scientific & Technology Research, 2014
The emitter formation constitutes a crucial step in the manufacturing of the crystalline silicon solar cells. Several techniques are used in the photovoltaic industry and the most well-known one is based on the POCl3 diffusion in cylindrical quartz tube. Despite the efficiency of this technique to be reproducible, economic and simple, it presents the major inconvenient to have a heavily doped region near the surface which induces a high minority carrier recombination. To limit this effect, an optimisation of diffused phosphorous profiles is required. Our modelling of phosphorus profiles is summarized in the presence of an erfc distribution near to the surface and other Gaussian distribution in the bulk region of the emitter. However, this work is devoted to study the effects of the temperature, diffusion time, surface concentration and doping profile on the crystalline silicon solar cells performances by using the new parameters. The first results of our numerical modelling carried out by the Silvaco Atlas® simulation package show the possibility to improve the efficiency by 2.78%. This result is also confirmed by the IQE calculus which present an obvious enhancement in short wavelength region (380-450nm) about 23%.
Effect of oxygen ambient during phosphorous diffusion on silicon solar cell
Journal of Renewable and Sustainable Energy, 2012
Selective emitters design and optimization for thermophotovoltaic applications J. Appl. Phys. 111, 084316 (2012) Effect of Gaussian doping on the performance of a n+-p thin film polycrystalline solar cell under illumination J. Renewable Sustainable Energy 4, 023118 A scattering model for nano-textured interfaces and its application in opto-electrical simulations of thin-film silicon solar cells J. Appl. Phys. 111, 083108 (2012) Light scattering at textured back contacts for n-i-p thin-film silicon solar cells Phosphorous (P) diffusion is the most important and crucial process in the fabrication of silicon (Si) solar cells from p-type Si substrates. P-diffusion using phosphorous-oxycholoride (POCl 3 ) as a precursor in a tube furnace had shown the best cell performance over the belt diffusion because of uniform dopant concentration all over the Si surface and gettering of metallic impurities present in the substrate. The emitter formation by using POCl 3 is a complex and advanced process which provides the gettering and forming the unwanted dead layer on the front surface due to inactive phosphorous. Along with temperature, the ambient conditions during the diffusion process, such as gas flow rates and their composition, flow kinetics also have an impact on the emitter properties. In the present paper, the impact of oxygen (O 2 ) flow during the diffusion process on the emitter formation and the solar cell performance were studied. It has been found that, the presence of oxygen during the diffusion process influences the concentration of inactive phosphorous over the surface and the gettering process as well. The optimized oxygen flow shows an improvement in the effective minority carrier lifetime of $24 ls after diffusion and an absolute efficiency gain of 0.2% at pilot production.
Solar Energy Materials and Solar Cells, 2013
Dual-junction solar cells formed by a GaAsP or GalnP top cell and a silicon bottom cell seem to be attractive candidates to materialize the long sought-for integration of III-V materials on silicon for photovoltaic applications. When manufacturing a multi-junction solar cell on silicon, one of the first processes to be addressed is the development of the bottom subcell and, in particular, the formation of its emitter. In this study, we analyze, both experimentally and by simulations, the formation of the emitter as a result of phosphorus diffusion that takes place during the first stages of the epitaxial growth of the solar cell. Different conditions for the Metal-Organic Vapor Phase Epitaxy (MOVPE) process have been evaluated to understand the impact of each parameter, namely, temperature, phosphine partial pressure, time exposure and memory effects in the final diffusion profiles obtained. A model based on SSupremlV process simulator has been developed and validated against experimental profiles measured by ECV and SIMS to calculate P diffusion profiles in silicon formed in a MOVPE environment taking in consideration all these factors.
Diffusion-free high efficiency silicon solar cells
Progress in Photovoltaics: Research and Applications, 2012
Traditional POCl 3 diffusion is performed in large diffusion furnaces heated to~850 C and takes an hour long. This may be replaced by an implant and subsequent 90-s rapid thermal annealing step (in a firing furnace) for the fabrication of p-type passivated emitter rear contacted silicon solar cells. Implantation has long been deemed a technology too expensive for fabrication of silicon solar cells, but if coupled with innovative process flows as that which is mentioned in this paper, implantation has a fighting chance. An SiOx/SiN y rear side passivated p-type wafer is implanted at the front with phosphorus. The implantation creates an inactive amorphous layer and a region of silicon full of interstitials and vacancies. The front side is then passivated using a plasma-enhanced chemical vapor deposited SiN x H y . The wafer is placed in a firing furnace to achieve dopant activation. The hydrogen-rich silicon nitride releases hydrogen that is diffused into the Si, the defect rich amorphous front side is immediately passivated by the readily available hydrogen; all the while, the amorphous silicon recrystallizes and dopants become electrically active. It is shown in this paper that the combination of this particular process flow leads to an efficient Si solar cell. Cell results on 160-mm thick, 148.25-cm 2 Cz Si wafers with the use of the proposed traditional diffusion-free process flow are up to 18.8% with a V oc of 638 mV, J sc of 38.5 mA/cm 2 , and a fill factor of 76.6%.