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DC‐sputtered ZnO:Al as transparent conductive oxide for silicon heterojunction solar cells with µc‐Si:H emitter
Author(s) -
Madani Ghahfarokhi Omid,
Chakanga Kambulakwao,
Geissendoerfer Stefan,
Sergeev Oleg,
Maydell Karsten,
Agert Carsten
Publication year - 2015
Publication title -
progress in photovoltaics: research and applications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.286
H-Index - 131
eISSN - 1099-159X
pISSN - 1062-7995
DOI - 10.1002/pip.2570
Subject(s) - materials science , optoelectronics , wafer , passivation , solar cell , schottky barrier , heterojunction , transparent conducting film , common emitter , energy conversion efficiency , fabrication , indium tin oxide , silicon , nanotechnology , layer (electronics) , diode , medicine , alternative medicine , pathology
Silicon heterojunction (SHJ) solar cells are highly interesting, because of their high efficiency and low cost fabrication. So far, the most applied transparent conductive oxide (TCO) is indium tin oxide (ITO). The replacement of ITO with cheaper, more abundant and environmental friendly material with texturing capability is a promising way to reduce the production cost of the future SHJ solar cells. Here, we report on the fabrication of the SHJ solar cells with direct current‐sputtered aluminum‐doped zinc oxide (ZnO:Al) as an alternative TCO. Furthermore, we address several important differences between ITO and the ZnO:Al layers including a high Schottky barrier at the emitter/ZnO:Al interface and a high intrinsic resistivity of the ZnO:Al layers. To overcome the high Schottky barrier, we suggest employing micro‐crystalline silicon (µc‐Si:H) emitter, which also improves temperature threshold and passivation of the solar cell precursor. In addition, we report on the extensive studies of the effect of the ZnO:Al deposition parameters including layer thickness, oxygen flow, power density and temperature on the electrical properties of the fabricated SHJ solar cells. Finally, the results of our study indicate that the ZnO:Al deposition parameters significantly affect the electrical properties of the obtained solar cell. By understanding and fine‐tuning all these parameters, a high conversion efficiency of 19.2% on flat wafer (small area (5 × 5 mm 2 ) and without any front metal grid) is achieved. Copyright © 2014 John Wiley & Sons, Ltd.