Extended high temperature Al gettering for improvement and homogenization of minority carrier diffusion lengths in multicrystalline Si

• Published in: Solar energy materials and solar cells Vol. 70; no. 2; pp. 231 - 238
• Main Authors: Joshi, Subhash M, Gösele, Ulrich M, Tan, Teh Y
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 15-12-2001; Elsevier
• Subjects: Aluminum gettering; Applied sciences; Dissolution; Energy; Exact sciences and technology; High temperature effects; Impurities; Minority carrier diffusion length; Multicrystalline silicon; Natural energy; Photovoltaic conversion; Photovoltaic effects; Precipitation (chemical); Silicon wafers; Solar cells; Solar cells. Photoelectrochemical cells; Solar energy; Solar cells; Aluminum gettering; Multicrystalline silicon; Minority carrier diffusion length; Solar cell; Dislocation density; Semiconductor materials; Impurity; Charge carrier mobility; Polycrystal; Aluminium; Silicon; Gettering; Diffusion length
• ISSN: 0927-0248; 1879-3398
• DOI: 10.1016/S0927-0248(01)00029-0

Multicrystalline Si for photovoltaic applications is a very inhomogeneous material with localized regions of high dislocation density and large impurity and precipitate concentrations which limit solar cell efficiency by acting as carrier recombination sites. Due to slow dissolution of precipitates in multicrystalline Si, these regions cannot be improved by conventional P and Al gettering treatments for removal of metal impurities which give good results for single crystal Si. It is shown that an extended high temperature Al gettering treatment can improve minority carrier diffusion lengths in these low quality regions and homogenize the electrical properties of multicrystalline Si wafers.