Aluminum gettering in photovoltaic silicon

¹ State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou, 310027, P.R. China
² IHP, Im Technologiepark 25, 15236 Frankfurt (Oder), Germany

Corresponding author: mseyang@dial.zju.edu.cn

Received: 2 July 2003
Accepted: 15 December 2003
Published online: 15 July 2004

Abstract

The effect of aluminum gettering on different silicon materials used for solar cells has been investigated by means of microwave photoconductivity decay (μ-PCD) and electron beam induced current (EBIC). μ-PCD measurement revealed that the lifetime of multicrystalline silicon (mc-Si) with a lower initial lifetime could be increased by high temperature gettering (1000 °C), while that of mc-Si with a higher initial lifetime could not be increased, but was even degraded. EBIC results revealed that no significant improvement of diffusion length was observed in both contaminated and uncontaminated wafers, while 850 °C Al gettering was employed. It is concluded that both the initial material quality and the thermal treatment have influences on the effect of Al gettering. In addition, dislocations with bright EBIC contrast were discovered in annealed mc-Si wafers, the origin of which is discussed.