Title :
Surface Passivation Properties of Stacked Doped PECVD a-Si:H Layers for Hetero-Structure c-Si Solar Cells
Author :
De Wolf, Stefaan ; Kondo, Michio
Author_Institution :
Res. Center for Photovoltaics, Nat. Inst. of Adv. Ind. Sci. & Technol., Ibaraki
Abstract :
Hetero-structures, such as the crystalline silicon (c-Si)/doped plasma-enhanced chemical vapor deposited (PECVD) amorphous silicon (a-Si:H) structure, are an elegant way to avoid recombination losses at the electrical contacts of high conversion efficiency photovoltaic devices. To find a good compromise between limited charge carrier recombination at the surface and a limited resistivity of the contact, sandwich structures such as c-Si (p or n)/a-Si:H(i)/ a-Si:H (p+ or n+) have been proposed in the past. In this paper we report on the surface passivation properties of such stacked doped a-Si:H layers, with a total thickness of only a few nm. Whereas subsequent deposition of a-Si:H (n+) films on thin a-Si:H (i) layers improves the surface passivation quality, a clear passivation degradation is seen when a-Si:H (i) layers are covered by a-Si:H (p+) films. The observed trends are irrespective of the wafer-type. This article discusses possible causes for these phenomena and a model for the recombination-mechanism is proposed
Keywords :
amorphous semiconductors; electrical contacts; electrical resistivity; elemental semiconductors; hydrogen; passivation; plasma CVD; sandwich structures; semiconductor growth; semiconductor heterojunctions; semiconductor thin films; silicon; solar cells; surface recombination; Si-Si:H; Si:H; amorphous silicon films; charge carrier recombination; contact resistivity; crystalline silicon-doped plasma-enhanced chemical vapor deposited amorphous silicon structure; electrical contacts; heterostructure silicon solar cells; high conversion efficiency photovoltaic devices; passivation degradation; sandwich structures; stacked doped PECVD amorphous silicon layers; surface passivation properties; wafer-type; Amorphous silicon; Chemicals; Contacts; Crystallization; Passivation; Photovoltaic cells; Photovoltaic systems; Plasma chemistry; Plasma devices; Plasma properties;
Conference_Titel :
Photovoltaic Energy Conversion, Conference Record of the 2006 IEEE 4th World Conference on
Conference_Location :
Waikoloa, HI
Print_ISBN :
1-4244-0017-1
Electronic_ISBN :
1-4244-0017-1
DOI :
10.1109/WCPEC.2006.279746
