Excellent Average Diffusion Lengths of 600 ¦Ìm of N-Type Multicrystalline Silicon Wafers After the Full Solar Cell Process Including Boron Diffusion

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• 作者：Bernhard Michl ; Jan Benick ; Armin Richter ; Martin Bivour ; Jeannie Yong ; Rob Steeman ; Martin C. Schubert ; Stefan W. Glunz
• 关键词：N-type ; Multicrystalline ; Boron diffusion ; Lifetime ; Silicon
• 刊名：Energy Procedia
• 出版年：2013
• 出版时间：2013
• 年：2013
• 卷：33
• 期：Complete
• 页码：41-49
• 全文大小：883 K

文摘

In this paper we investigate the material quality of n- and p-type multicrystalline silicon wafers after different high- temperature steps, as applied during cell processing. Both materials start with a high initial bulk diffusion length of around 440 ¦Ìm (harmonic mean of the whole wafer) which is further improved by the solar cell process. A diffusion length of 510 ¦Ìm was measured after phosphorus and boron diffusion and firing in the n-type material. The p-type wafers showed diffusion lengths of 540 ¦Ìm after phosphorus diffusion and firing. These diffusion lengths were measured at a generation rate of 1/20 sun close to maximum power point injection conditions of a solar cell. At higher injection levels both materials reach 600 ¦Ìm diffusion length. The high material quality of n-type material maintained after the high temperature boron diffusion is remarkable. An efficiency analysis shows that these excellent diffusion lengths allow for high efficiency devices exceeding 20 % efficiency.