Green scalable vapor texture etching for multicrystalline silicon wafers

Abstract

In recent years, the low‐cost diamond‐wire (DW) slicing has been widely used for single‐crystalline silicon (sc‐Si) wafers, and this makes sc‐Si solar cells very attractive to the market. On the contrary, the adoption of DW slicing for multicrystalline (mc‐Si) wafers is troublesome because of poor texturing quality in the existing production lines using acid solutions. We have developed a vapor texture etching (VTE) process with the combination of both acid and reacted vapors for DW sliced mc‐Si wafers. The etching process was rather simple and low cost. More importantly, the acid usage was low and recyclable, so that the acid emission was low as well. Its scale‐up was easy and straightforward. In this lab‐scale reactor, more than 50 full‐size wafers could be processed each time. The etched wafers had uniform appearance and low reflectivity, around 10%. After the nanostructure pores were enlarged by post treatments to minimize surface recombination, the full‐size mc‐Si solar cell fabricated by Solartech could achieve an efficiency of 19.7% using the Passivated Emitter and Rear Contact (PERC) structure, which was comparable with the average production efficiency.

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“…Texturization of silicon is a crucial step in solar cells fabrication processes that ultimately enhances conversion e ciencies by improving light trapping ability [1,2]. There are currently a variety of techniques that can used for the texturization of single-and multi-crystalline silicon wafers.…”