Tube diffusion is the de facto standard way to form the p-n junction in industrial silicon solar cells. The majority of silicon solar cells are produced from p-type silicon and consequently, a phosphorus diffusion is used to create a heavily doped n-type layer at the surface. This is done by placing the silicon wafer in a high-temperature tube furnace and (1) first growing a oxide layer with a high phosphorous concentration (using POCl3 as the phosphorous precursor) and (2) diffusing the phosphorus into the silicon wafer. This n-type layer is typically referred to as an emitter, a term which was taken from the bipolar transistor field. A correct term would be electron collector as is advocated by Cuevas et al. . The phosphorus diffusion is one of the most critical steps in solar cell manufacturing. More information can be found on https://pv-manufacturing.org/solar-cell-manufacturing/tube-diffusion/
 A. Cuevas and D. Yan, “Misconceptions and Misnomers in Solar Cells”, IEEE Journal of Photovoltaics, vol. 3, pp. 916-923, 2013.
This video is an online educational resource developed for the https://pv-manufacturing.org/ website by Daniel Chen, Moonyong Kim, Huy Duc Dao and Jack Colwell in a project headed by Associate Professor Bram Hoex. The project funding was provided by the Australian Centre for Advanced Photovoltaics (ACAP) under Grant “CGR3 – Development of online educational resources for PV manufacturing education” and the Faculty of Engineering of UNSW Sydney.
More information about the A/Prof Bram Hoex’s research group
More information about UNSW Sydney https://www.unsw.edu.au/
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