Borosilicate spray-on glass solutions for fabrication silicon solar cell back surface field
Article publication date: 2 July 2018
The purpose of this paper is to develop a method of preparing spray-on dopant solutions that enable obtaining a p+ region forming a back-surface field (BSF) during the diffusion doping process. The spray-on method used allows to decrease the costs of dopant solution application, which is particularly significant for new low-cost production processes.
This paper presents steps of production of high concentration boron dopant solutions enabling diffusion doping of crystalline p-type silicon surfaces. To check the fabricated dopant solutions for stability and suitability for spray-on application, their viscosity and density were measured in week-long intervals. The dopant solutions described in this paper were used in a series of diffusion doping processes to confirm their suitability for BSF production.
A method of preparing dopant solutions with parameters enabling depositing them on silicon wafers by the spray-on method has been established. Due to hygroscopic properties of the researched dopant solutions, a maximum surrounding atmosphere humidity has been established. The solutions should not be applied by the spray-on method, if this humidity value is exceeded. The conducted derivatographic examination enabled establishing optimal drying conditions.
The paper presents a new composition of a dopant solution which contains high concentration of boron and may be applied by the spray-on method. Derivatographic examination results, as well as equations describing the relation between dopant solution density and viscosity and storage time are also original for this research. The established dependencies between the sheet resistance of the fabricated BSF and the diffusion doping time are other new elements described in the paper.
This work was partially supported by the Ministry of Science and Higher Education funding for statutory activities of Researchers of the Faculty of Automatic Control, Electronics and Computer Science of Silesian University of Technology and partially by the “Innovative flexible photovoltaic cover” project No. GEKON2/O4/268473/23/2016. The project is co-financed by: The National Centre for Research and Development and The National Fund for Environmental Protection and Water Management, under the GEKON (Generator of Ecological Concepts) programme.
Filipowski, W., Drabczyk, K., Wróbel, E., Sobik, P., Waczynski, K. and Waczynska-Niemiec, N. (2018), "Borosilicate spray-on glass solutions for fabrication silicon solar cell back surface field", Microelectronics International, Vol. 35 No. 3, pp. 172-176. https://doi.org/10.1108/MI-12-2017-0075
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