Design of porous silicon antireflection coatings for silicon solar cells

A porous silicon (PS) layer formed electrochemically in the outer part of t he n(+) emitter of p-ni Si junctions can be used as an efficient antireflec tion coating (ARC). A two-step procedure is presented which can determine t he electrochemical parameters leading to the formation of an optimized sing le-layer PS ARC. Single-layer PS ARCs achieving approximate to 7% effective reflectance between 400 and 1000 nm are obtained on shallow p-n(+) junctio n solar cells. To reduce the reflectance further, the design of double-laye r ARCs based on PS is investigated. PS layers with different porosities can be realized in a single experiment by modulating the current density durin g the electrochemical process. It is shown theoretically and experimentally that such PS structures can lead to an effective reflectance below 3%. (C) 2000 Elsevier Science S.A. All rights reserved.