Real-time monitoring and process control in amorphous∕crystalline silicon heterojunction solar cells by spectroscopic ellipsometry and infrared spectroscopy

Abstract

In amorphous∕crystalline siliconheterojunctionsolar cells, we have performed real-time thickness control of hydrogenated amorphous silicon ( a ‐ Si : H ) layers with a precision better than ± 1 Å by applying spectroscopic ellipsometry (SE). A heterojunctionsolar cell fabricated by this process shows a relatively high conversion efficiency of 14.5%. At the amorphous∕crystalline interface, however, infrared attenuated total reflectionspectroscopy(ATR) revealed the formation of a porous a ‐ Si : H layer with a large SiH 2 -hydrogen content of 27 at. %. Based on SE and ATR results, we discuss the growth processes and structures of a ‐ Si : H in heterojunctionsolar cells.