Analysis of Texture Etching to Reduce Laser-Induced Damage in Boron-Doped Selective Emitters

The photovoltaic industry is undergoing a transition from p-type to n-type silicon substrates, with most solar cells incorporating boron-doped emitters. Boron laser-assisted selective emitter is a key area of research in the mass production of high-efficiency devices. However, laser processing can damage silicon wafers and reduce the minority carrier lifetime. This paper presents an analysis of a process developed to obtain boron-doped emitters using laser-assisted doping, combined with texture etching to reduce surface damage. Boron-doped regions exhibit resistance to KOH-based etching, thereby enabling selective material removal and making this approach suitable for the fabrication of selective emitters. Boron was deposited by spin-coating, and diffusion was performed with a Nd-YAG laser. The samples were analysed by SEM images and minority carrier lifetime and sheet resistance measurements. SEM images revealed that, despite the presence of boron in the laser-processed areas, the anisotropic etching produced textured surfaces. The decrease in minority carrier lifetime was smaller in the samples processed using the proposed method compared to those subjected to the reference process. In conclusion, texture etching can be performed after boron diffusion to minimize silicon damage caused by laser processing and to increase the sheet resistance of the doped regions.