PO x /Al 2 O 3 Stacks for c-Si Surface Passivation: Material and Interface Properties

Theeuwes, Roel J.; Kessels, Wilhelmus M. M.; Berghuis, Wilhelmus J. H.; Black, Lachlan E.; Koushik, Dibyashree; Beyer, Wolfhard; Macco, Bart; Melskens, Jimmy

doi:10.1021/acsaelm.1c00516

Journal Article

FZJ-2021-05689

PO x /Al 2 O 3 Stacks for c-Si Surface Passivation: Material and Interface Properties

Theeuwes, R. J. ; Melskens, J. ; Black, L. E. ; Beyer, W.FZJ* ; Koushik, D. ; Berghuis, W. J. H. ; Macco, B. ; Kessels, W. M. M. (Corresponding author)

2021
ACS Publications Washington, DC

ACS applied electronic materials 3(10), 4337 - 4347 (2021) [10.1021/acsaelm.1c00516]

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Please use a persistent id in citations: http://hdl.handle.net/2128/30283 doi:10.1021/acsaelm.1c00516

Abstract: Phosphorus oxide (POx) capped by aluminum oxide (Al2O3) has recently been discovered to provide excellent surface passivation of crystalline silicon (c-Si). In this work, insights into the passivation mechanism of POx/Al2O3 stacks are gained through a systematic study of the influence of deposition temperature (Tdep = 100–300 °C) and annealing temperature (Tann = 200–500 °C) on the material and interface properties. It is found that employing lower deposition temperatures enables an improved passivation quality after annealing. Bulk composition, density, and optical properties vary only slightly with deposition temperature, but bonding configurations are found to be sensitive to temperature and correlated with the interface defect density (Dit), which is reduced at lower deposition temperature. The fixed charge density (Qf) is in the range of + (3–9) × 1012 cm–2 and is not significantly altered by annealing, which indicates that the positively charged entities are generated during deposition. In contrast, Dit decreases by 3 orders of magnitude (∼1013 to ∼1010 eV–1 cm–2) upon annealing. This excellent chemical passivation is found to be related to surface passivation provided by hydrogen, and mixing of aluminum into the POx layer, leading to the formation of AlPO4 upon annealing.

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