Conducting two-phase silicon oxide layers for thin-film silicon solar cells

Abstract

We present optical properties and microstructure analyses of hydrogenated silicon suboxide layers containing silicon nanocrystals (nc-SiO x :H). This material is especially adapted for the use as intermediate reflecting layer (IRL) in micromorph silicon tandem cells due to its low refractive index and relatively high transverse conductivity. The nc-SiO x :H is deposited by very high frequency plasma enhanced chemical vapor deposition from a SiH 4 /CO 2 /H 2 /PH 3 gas mixture. We show the influence of H 2 /SiH 4 and CO 2 /SiH 4 gas ratios on the layer properties as well as on the micromorph cell when the nc-SiO x :H is used as IRL. The lowest refractive index achieved in a working micromoph cell is 1.71 and the highest initial micromoph efficiency with such an IRL is 13.3 %.

Mixed phase silicon oxide layers for thin-film silicon solar cells

“…Hydrogenated silicon oxide containing nanocrystalline silicon grains (nc-SiO x ) has attracted much interest in the last years because of different applications in thin-film silicon solar cells: First, p-type nc-SiO x is an excellent window and anti-reflection layer, due to lower absorption coefficient and lower refractive index when compared to p-type µc-Si layers [1]. Second, n-type nc-SiO x can be used as intermediate reflecting layer, when inserted between two sub-cells of a tandem configuration, allowing for advanced light-trapping schemes [2][3][4][5]. Third, tunable resistance of p-and n-type nc-SiO x can help to reduce the impacts of shunts on the electrical cell parameters [1,6].…”

Mechanism of Surface Morphology Development of Tin Oxide Transparent Conductive Films

“…This is an essential property for increasing the external quantum efficiency (QE) of amorphous silicon solar cells. [9][10][11] At the same time, the light diffraction at wavelength longer than 700 nm is expected to increase the light absorption in the microcrystalline silicon (c-Si) layer, which is employed in the bottom cells of tandem junction solar cells. 12,13) Efforts to improve the surface morphology have been continued in these areas in recent years.…”