Oriented recrystallization of silicon layers for silicon thin-film solar cells

Abstract

A zone melting heater (ZMH) was used for oriented recrystallization of thin Si layers which were deposited on different encapsulated ceramic as well as on graphite substrates. The encapsulation consisted of high quality SiO/sub 2/ and SiN/sub x/ layers deposited by plasma enhanced chemical vapor deposition (PECVD). The mechanical stability of such SiO/sub 2/ and SiN/sub x/ layer systems as well as the diffusion of electrically active impurities out of the substrate through these layers were investigated. A newly designed moveable large area heater (LAH) with halogen lamps mounted perpendicular to the scanning direction was used to recrystallize thin Si layers deposited on various mc- and ribbon-Si substrates covered with perforated SiO/sub 2/ intermediate layers. An algorithm to detect the melting point automatically was developed and homogeneous recrystallization out of these seeding holes could be achieved.