1.
T F Wietler; B Min; S Reiter; Y Larionova; R Reineke-Koch; F Heinemeyer; R Brendel; A Feldhoff; J Krügener; D Tetzlaff; R Peibst
In: IEEE Journal of Photovoltaics, Bd. 9, Nr. 1, S. 89-96, 2019, ISSN: 2156-3381.
@article{Wietler2019,
title = {High Temperature Annealing of ZnO:Al on Passivating POLO Junctions: Impact on Transparency, Conductivity, Junction Passivation, and Interface Stability},
author = {T F Wietler and B Min and S Reiter and Y Larionova and R Reineke-Koch and F Heinemeyer and R Brendel and A Feldhoff and J Krügener and D Tetzlaff and R Peibst},
doi = {10.1109/JPHOTOV.2018.2878337},
issn = {2156-3381},
year = {2019},
date = {2019-01-01},
journal = {IEEE Journal of Photovoltaics},
volume = {9},
number = {1},
pages = {89-96},
abstract = {We investigate the enhancement in transparency and conductivity of aluminum doped zinc oxide (ZnO:Al) layers upon high-temperature annealing and its impact on contact resistance, as well as, on passivation properties of carrier selective junctions based on doped polycrystalline Si on a passivating silicon oxide (POLO). The temperature stability of these junctions allows annealing of the ZnO:Al/POLO combination up to 600 °C. We prepare ZnO:Al films by dc magnetron sputtering at room temperature. We determine the complex refractive index of ZnO:Al in dependence of post-deposition annealing (PDA) temperature by spectroscopic ellipsometry. High-temperature annealing improves the conductivity and reduces the absorption within ZnO:Al. The optical losses in a ZnO:Al/POLO stack are rather limited by the poly-Si layer than by the ZnO:Al. The sheet resistance improves from roughly 20 000 Ω/sq for 80 nm thick as-deposited ZnO:Al films to 72 Ω/sq after fast firing at 600 °C. At the same time, PDA cures the damage induced in the POLO junctions during ZnO:Al deposition. After PDA with Al$_textx$O$_texty$capping layers, the passivation quality even surpasses the initial level. A transmission electron microscopy analysis of the interface between the ZnO:Al and the underlying poly-Si reveals the formation of a silicon oxide like interfacial layer after PDA at 400 °C. This interfacial layer causes a high contact resistivity of the metal/ZnO:Al/POLO-junction and could limit the thermal budget for cell processing. Our results indicate that after successful process adjustment, ZnO:Al could substitute In-based transparent conductive oxides on POLO cells for cost reasons, as well as, enable a high efficiency potential.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
We investigate the enhancement in transparency and conductivity of aluminum doped zinc oxide (ZnO:Al) layers upon high-temperature annealing and its impact on contact resistance, as well as, on passivation properties of carrier selective junctions based on doped polycrystalline Si on a passivating silicon oxide (POLO). The temperature stability of these junctions allows annealing of the ZnO:Al/POLO combination up to 600 °C. We prepare ZnO:Al films by dc magnetron sputtering at room temperature. We determine the complex refractive index of ZnO:Al in dependence of post-deposition annealing (PDA) temperature by spectroscopic ellipsometry. High-temperature annealing improves the conductivity and reduces the absorption within ZnO:Al. The optical losses in a ZnO:Al/POLO stack are rather limited by the poly-Si layer than by the ZnO:Al. The sheet resistance improves from roughly 20 000 Ω/sq for 80 nm thick as-deposited ZnO:Al films to 72 Ω/sq after fast firing at 600 °C. At the same time, PDA cures the damage induced in the POLO junctions during ZnO:Al deposition. After PDA with Al$_textx$O$_texty$capping layers, the passivation quality even surpasses the initial level. A transmission electron microscopy analysis of the interface between the ZnO:Al and the underlying poly-Si reveals the formation of a silicon oxide like interfacial layer after PDA at 400 °C. This interfacial layer causes a high contact resistivity of the metal/ZnO:Al/POLO-junction and could limit the thermal budget for cell processing. Our results indicate that after successful process adjustment, ZnO:Al could substitute In-based transparent conductive oxides on POLO cells for cost reasons, as well as, enable a high efficiency potential.
2.
J B Nehmann; N Ehrmann; R Reineke-Koch; D W Bahnmann
In: Thin Solid Films, Bd. 556, S. 168-173, 2014.
@article{Nehmann2014,
title = {Aluminum-doped zinc oxide sol-gel thin films: Influence of the sol's water content on the resistivity},
author = {J B Nehmann and N Ehrmann and R Reineke-Koch and D W Bahnmann},
doi = {10.1016/j.tsf.2014.01.052},
year = {2014},
date = {2014-04-01},
journal = {Thin Solid Films},
volume = {556},
pages = {168-173},
keywords = {},
pubstate = {published},
tppubtype = {article}
}