Regensburg 2013 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 93: Photovoltaics (HL, jointly with CPP, O)
HL 93.14: Vortrag
Freitag, 15. März 2013, 12:45–13:00, H2
Charge trapping in Al2O3 passivation layers for silicon solar cells — •Paul Jordan1, Frank Benner1, Ingo Dirnstorfer1, and Thomas Mikolajick1,2 — 1NaMLab gGmbH, Dresden, Germany — 2Lehrstuhl für Nanoelektronische Materialien, TU Dresden, Dresden, Germany
Novel highly efficient silicon solar cells require an excellent level of surface passivation, to minimize recombination losses of photo-generated carriers. During the last decade, the dielectric Al2O3 became the material of choice for the passivation of p-type silicon. The excellent passivation properties are mainly caused by negative charges located within the dielectric. In this study the origin of the negative charges is investigated using capacitance-voltage and microwave detected photoconductivity measurements. It will be shown that the negative charges are partly caused by electrons, injected from silicon into the dielectric. The trapping dynamics are analyzed by the means of the post program discharge technique, which is commonly applied for memory devices. Furthermore, the trapping and detrapping rates depend on the thickness of the ultra-thin SiO2 interface between Si and Al2O3. For an interface thickness of about 2 nm, the asymmetry of trapping and detrapping rates significantly enhances the negative charge density. As a consequence an optimum interface thickness is essential for the excellent passivation property of Al2O3.