Large-Area Crystalline Silicon Solar Cell Using Novel Antireflective Nanoabsorber Texturing Surface by Multihollow Cathode Plasma System and Spin-On Doping

Utpal Gangopadhyay,Sukhendu Jana,Sayan Das

doi:10.1155/2013/738326

Abstract

We present 11.7% efficient p-type crystalline silicon solar cells with a nanoscale textured surface and no dielectric antireflection coating. We propose nanocrystalline-like textured surface consisting of nanocrystalline columnar structures of diameters from 50 to 100 nm and depth of about 500 nm formed by reactive-ion etching (RIE) in multihollow cathode system. This novel nano textured surface acts as an antireflective absorbing surface of c-Si abbreviate as ARNAB (antireflective nanoabsorber). Light shining on the surface of RIE-etched silicon bounces back and forth between the spikes in such a way that most of it never comes back. Radio frequency (RF) hollow cathode discharge allows an improvement of plasma density by an order of magnitude in comparison to standard RF parallel-plate discharge. Desirable black silicon layer has been achieved when RF power of about 20 Watt per one hollow cathode glow is applied for our multihollow cathode system. The RF power frequency was 13.56 MHz. The antireflection property of ARNAB textured surface has been investigated and compared with wet-textured and PECVD coated silicon samples. Solar cell using low-cost spin-on coating technique has been demonstrated in this paper. We have successfully achieved 11.7% efficient large area (98 cm2) ARNAB textured crystalline silicon solar cell using low-cost spin-on coating (SOD) doping.

Highlights

Surface texturization is usually promoted to enhance the light absorption in silicon solar cells [1]
We have reported the formation of uniform antireflective nanoabsorber (ARNAB) texturing silicon surface on crystalline silicon (c-Si) using Radio frequency (RF) multihollow cathode system
We have carried out scanning electron microscope (SEM) investigation of these randomly ARNAB textured etched silicon surfaces

Summary

Introduction

Surface texturization is usually promoted to enhance the light absorption in silicon solar cells [1]. Wet anisotropic chemical etching technique used to form random pyramidal structure on ⟨100⟩ mono-crystalline silicon wafers usually is not effective in texturing of low-cost multicrystalline silicon wafers because of random orientation nature. Expensive antireflection layers like silicon nitride and magnesium fluoride have been applied to mc-Si solar cells front surface to reduce light reflection. Jansen et al [10] reported on a black silicon method in planar parallel-plate system reactors for SF6/CHF3/O2 plasma. In the SF6/O2 plasma, SF6 is the source of active fluorine that etches silicon and O2 supply oxygen radicals that passivate the surface of the etched silicon structures. An extensive study of SF6/O2 RIE in parallel-plate reactors was done by Sandia group [11] for silicon solar cell application.

13.56 MHz R F power

Experimental

Results and Discussion

Conclusion