On the emitter formation in nanotextured silicon solar cells to achieve improved electrical performances

• Published in: Solar energy materials and solar cells Vol. 152; pp. 94 - 102
• Main Authors: Kafle, Bishal, Schön, Jonas, Fleischmann, Christoph, Werner, Sabrina, Wolf, Andreas, Clochard, Laurent, Duffy, Edward, Hofmann, Marc, Rentsch, Jochen
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.08.2016
• Subjects: Atmospheric pressure; Black silicon; Dry etching; Electron beam induced current (EBIC); Emitters; Expansion; Formations; Junction depth; Multicrystalline silicon; Nanostructure; Nanotexture; Photovoltaic cells; Process simulation; Silicon; Solar cells; Wafers; Solar cells; Atmospheric pressure; Dry etching; Multicrystalline silicon; Black silicon; Electron beam induced current (EBIC); Nanotexture; Process simulation; Junction depth
• ISSN: 0927-0248; 1879-3398
• DOI: 10.1016/j.solmat.2016.03.031

In this paper, we study the effect of an enlarged surface area of nanotextured crystalline silicon wafers on the formation of n-type emitters using a tube diffusion process applying POCl3 as P dopant source. A fast, single-step and industrially viable F2-based dry texturing process is used to perform nanotexturing of Si wafers. This process is presented as an alternative route of nanotexturing in comparison to the two-step nanotexturing approach of creating black silicon and then modifying it with an alkaline or acidic solution. Predictive simulations of phosphorous in-diffusion aided by microscopical characterization of the selected emitters are used to understand the formation of emitter in nanotextured surfaces. Based on these investigations, we show that the optimized emitter leads to a significant improvement in short circuit current density (Jsc≥0.7mA/cm2) of nanotextured mc-Si solar cells in comparison to the industrial standard acidic textured solar cells. •Nanotexture in multicrystalline silicon formed by a plasma-less dry etching process.•Formation of n-type emitter investigated by 3D simulations and characterizations.•High phosphorous concentration is present near the surface region of nanostructure.•Formation of a deep and relatively planar p–n junction beneath the nanostructures.•Deposition temperature and O2 flux have determining effect on emitter properties.