Amorphous Silicon Oxinitride in Silicon Thin-film Solar Cells

Abstract

Silicon oxide is a promising material for silicon thin-film solar cells. As a doped layer it shows low parasitic absorption while as an intrinsic layer it can be used as a high band gap absorber in multijunction solar cells. Whereas doped silicon oxide layers prepared with CO2 are widely investigated, intrinsic layers and the use of N2O as a source gas for oxygen incorporation in silicon thin-film solar cells have not received much attention yet. Therefore we present the optical and electrical properties of doped and intrinsic silicon oxinitride layers at varying N2O flow as well as their performance in single cells.We found that p-doped amorphous silicon oxinitride layers enhance the short circuit current and the open circuit voltage of amorphous silicon single cells while the fill factor is reduced due to higher series resistance. When N2O is added to the intrinsic layer of amorphous silicon single cells the cell performance deteriorates drastically which is attributed to increased defect density.