2021 Material Research Society (MRS) Conference (Boston, USA): Black silicon for PV—Which fabrication technology to choose?

Description

Black silicon (b-Si) surface texture that consists of nanoscale structures is well known to reduce the optical losses both in multi- and monocrystalline silicon solar cells. The enhanced surface recombination related to the increased surface area of nanostructures is no longer an issue as conformal atomic layer deposited thin films provide excellent surface passivation. [1] Furthermore, pn-junction formation and related control of dopant atoms inside nanostructures has resulted recently in totally recombination-free emitters yielding external quantum efficiencies even above unity in front-junction Si solar cells. [2] These developments have made the b-Si technology attractive for the PV industry as well.

So far only one black silicon fabrication technology has emerged as cost competitive technology to conventional texturization, that is, metal assisted chemical etching (MACE). [3] However, there are other b-Si fabrication technologies that have their benefits over MACE (e.g. extended infrared absorption) and which could find interest among PV industry, too. These include dry-etching as well as laser-based methods. All these technologies have seen lately great progress, so in this contribution we give an updated overview of b-Si fabrication methods and related achievements. Furthermore, in order to make a direct comparison of the methods easier, we present a systematic study on the properties of b-Si wafers fabricated in the same facility on sister wafers using three different fabrication methods: i) MACE ii) reactive ion etching and iii) femtosecond-laser. A special emphasis is placed on optical properties, recombination and surface passivation quality, surface morphology, silicon consumption, throughput, and patternability. Finally, the pros and cons of each method are discussed and the future outlook is given for each technology.

[1] P. Repo et al. IEEE Journal of Photovoltaics 3 (90-94) 2013.
[2] K. Chen et al. APL Materials (submitted 2021).
[3] K. Chen et al. Solar Energy Materials and Solar Cells 191 (1-8) 2019

Period	6 Dec 2021
Event title	Material Research Society Fall Meeting: Symposium EN04, Silicon for Photovoltaics
Event type	Conference
Location	Boston, United States, MassachusettsShow on map
Degree of Recognition	International