Ceramic Roller Inline Diffusion With Lowest Standard Deviation for Crystalline Si Solar Cells

Abstract

Crystalline silicon solar cells and modules have dominated terrestrial photovoltaic market. Inline diffusion as an alternative emitter fabrication method has been focused on due to its lower budget cost and higher throughput. In this study, phosphorus emitter with less metallic contamination was realized by means of ceramic roller inline diffusion (CRID) and diluted H3PO4 solution (5%) as a dopant source. A wide range of homogeneous sheet resistance ( R sq) (40–130 Ω/sq) was obtained at temperature increases from 810 to 870 °C with duration fixed on 20 min. A standard deviation (SD) of 2.1 Ω/sq was gained by CRID at the target R sq of 75 Ω/sq compared with the SD of 4.0 Ω/sq by reference tube diffusion (TD). The R sq can be adjusted from 71.1 to 115.6 Ω/sq by a removal of predefined “dead layer” in 1% KOH solution, which allows SD within a range of 2.1 to 5.2 Ω/sq. For a target R sq of 85 Ω/sq, cells with efficiency SD of 0.02% were achieved by CRID, which were reduced by 76.8% relative to that by TD. The results in combination with Suns-Voc measurement indicate that CRID cells with uniform emitters have high potential for efficiency enhancement based on our investigation, which are catering for higher cell performance with multibusbar design in the near future.