Optimizing Emitter Diffusion Process for Atmospheric Pressure Dry Nanotextured Monocrystalline PERC

Abstract

In this article, we present an optimization of the emitter diffusion for nanotextured p-type monocrystalline silicon solar cells using atmospheric pressure dry etching (ADE) in conjunction with a post-ADE short acidic etch in a passivated emitter and rear cell (PERC) architecture. The optimization of the phosphorus oxychloride diffusion process was realized by first investigating the emitter sheet resistance and emitter recombination current density to achieve improved electrical properties and cell performances at a later stage. The optimization of the diffusion process enables an excellent homogeneity for emitter sheet resistance of 105 Ω/sq with minimized standard deviation of 3%, a decreased emitter saturation current density of ∼120 fA/cm 2 , a peak doping concentration of 2.2 × 10 20 cm −3 and depth of the highly doped surface region of 20 nm, still in the range that is required for good contact formation. By step optimization of the emitter formation of ADE textured PERC solar cells, an efficiency improvement of 0.6% abs could be reached leading to best conversion efficiency of 20.9%. Index Terms-Atmospheric pressure dry etching (ADE), diamond-wire sawn (DWS), p-type monocrystalline silicon (mono-Si), POCl 3 emitter diffusion, POCl 3 emitter optimization, passivated emitter and rear cell (PERC). I. INTRODUCTION I N RECENT years, low reflectivity nanotexturing processes sometimes referred as "black silicon" (B-Si), have generated large interest within the silicon-based photovoltaic industry, leading to higher solar cell performances [1]-[8]. The plasmaless fluorine-based atmospheric pressure dry etching (ADE) process [6]-[11] is one of the several other texturing methods that is being used to form nanotextured surface on silicon wafer, Manuscript

An Artificial-Intelligence-Assisted Investigation on the Potential of Black Silicon Nanotextures for Silicon Solar Cells

“…The lateral surface area-to-projected surface area ratio, or the enhanced area factor (EAF), is a widely used metric to quantify the relative surface area. − Another metric is the surface-to-volume ratio or specific surface area (SSA), which was recently proposed to quantify the size of b-Si nanofeatures. , The b-Si optical performance is usually evaluated by the weighted average reflectance (WAR) calculated by the wavelength-dependent photon flux under an AM1.5G spectrum condition from a wavelength range of around 300–1100 nm . Although the application of MCCE b-Si has been proven successful in the industry for multi-Si, the research on integrating b-Si into high-efficiency solar cells is still at a relatively early stage, i.e., most of the published scientific articles are using Aluminum Back Surface Field (Al-BSF) architectures (95 articles identified in this work), while there are only a few using Passivated Emitter and Rear Contact (PERC) architectures, − Interdigitated Back Contact (IBC) architectures, − Tunnel Oxide Passivated Contact (TOPCon) architectures, − and heterojunction (HJT) architectures. , Due to the limited b-Si research in advanced architectures, the solar cell efficiency records using b-Si are lagging compared to those using conventional textures. Therefore, how well b-Si performs at the solar cell level using advanced architectures is still unknown.…”