Development of an emitter for industrial silicon solar cells using the doped oxide solid source diffusion technique

The aim of this paper is to demonstrate for the first time the feasibility of fabricating large-area screen-printed monocrystalline silicon solar cell s using the Doped Oxide Solid Source (DOSS) diffusion technique. This proce ss was applied to form the n(+)p emitter junction from highly doped sources prepared in a POCl3 ambient. The diffusions were performed under a pure ni trogen flow in the temperature range 900-1050 degreesC. In this investigati on attention was devoted to the influence of the source doping level on the fill factor. The solar cells were fabricated on industrial quality 4-inch Cz wafers using a simple processing sequence incorporating screen-printed c ontacts and a TiO2 antireflection coating deposited by spin-on. Fill factor s as high as 79% were obtained. The potential benefit of retaining for pass ivation purposes the thin residual oxide grown during phosphorus diffusion was evaluated. These first experiments led to a cell efficiency close to 10 %. (C) 2001 Elsevier Science Ltd. All rights reserved.