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Investigations on the passivation mechanism of AlN:H and AlN:H-SiN:H stacks

 
: Krugel, G.; Jenkner, F.; Moldovan, A.; Wolke, W.; Rentsch, J.; Preu, R.

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Fulltext urn:nbn:de:0011-n-3243974 (585 KByte PDF)
MD5 Fingerprint: 35d71d2316ae183c7f5b8ec81fa4fb9a
(CC) by-nc-nd
Created on: 7.10.2016


Energy Procedia 55 (2014), pp.797-804
ISSN: 1876-6102
International Conference on Crystalline Silicon Photovoltaics (SiliconPV) <4, 2014, S'Hertogenbosch>
English
Journal Article, Conference Paper, Electronic Publication
Fraunhofer IWM ()
Fraunhofer ISE ()
PV Produktionstechnologie und Qualitätssicherung; Silicium-Photovoltaik; Oberflächen - Konditionierung; Passivierung; Lichteinfang; passivation; AlN; nitride; Sputter

Abstract
In this paper, the properties of hydrogenated aluminum nitride layers (AlN:H) as an excellent passivation layer of silicon surfaces are examined. The structural and chemical properties of the AlN:H bulk are analyzed using a great variety of measurements techniques such as GI-XRD, FTIR, SEM, HR-TEM, corona charging and a thickness dependent measurements of the surface passivation. A model for the formation of negative fixed charges at the interface to silicon is presented based on the charge state of ionized point defects in AlN. Additionally, stacks of AlN:H and SiNx:H are introduced into silicon photovoltaics and their combination with two different types of thin low temperature silicon oxide layers is studied. Excellent passivation results are presented for highly doped p-type silicon and highly doped n-type silicon using the previous described stacks. Emitter saturation current densities of textured samples show, that 75 Omega/sq. phosphorous emitter can be passivated as efficient as with the typically used SiNx:H allowing maximum open circuit voltages of 657 mV. This is supported by measurement of cell parameters of p-type solar cells using these stacks as a combined anti-reflective coating and passivation layer. Furthermore, the passivation level reached for high efficiency 70 Omega/sq. boron emitters is nearly as high as with excellent passivating PECVD Al2O3/SiNx stacks. Emitter saturation current densities down to 61 fA/cm(2) are presented corresponding to a maximum open circuit voltage of 696 mV. This indicates that the invented stacks containing AlN:H can also be applied as combined anti-reflective coating and passivation layers in n-type cells.

: http://publica.fraunhofer.de/documents/N-324397.html