Optoelectronic properties of ultrathin ALD silicon nitride and its potential as a hole-selective nanolayer for high efficiency solar cells
| Autor: | Ruy S. Bonilla, Stuart A. Boden, Shona McNab, Edris Khorani, Peter R. Wilshaw, Tudor E. Scheul, Tasmiat Rahman |
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| Jazyk: | angličtina |
| Rok vydání: | 2021 |
| Předmět: |
Materials science
Silicon lcsh:Biotechnology chemistry.chemical_element 02 engineering and technology 01 natural sciences Band offset chemistry.chemical_compound Atomic layer deposition X-ray photoelectron spectroscopy lcsh:TP248.13-248.65 0103 physical sciences General Materials Science Quantum tunnelling 010302 applied physics Tandem business.industry Energy conversion efficiency General Engineering 021001 nanoscience & nanotechnology lcsh:QC1-999 Silicon nitride chemistry Optoelectronics 0210 nano-technology business lcsh:Physics |
| Zdroj: | APL Materials, Vol 8, Iss 11, Pp 111106-111106-11 (2020) |
| Popis: | Fully exploiting the power conversion efficiency limit of silicon solar cells requires the use of passivating contacts that minimize electrical losses at metal/silicon interfaces. An efficient hole-selective passivating contact remains one of the key challenges for this technology to be deployed industrially and to pave the way for adoption in tandem configurations. Here, we report the first account of silicon nitride (SiNx) nanolayers with electronic properties suitable for effective hole-selective contacts. We use x-ray photoemission methods to investigate ultra-thin SiNxgrown via atomic layer deposition, and we find that the band alignment determined at the SiNx/Si interface favors hole transport. A band offset ratio, ΔEC/ΔEV, of 1.62 ± 0.24 is found at the SiNx/Si interface for the as-grown films. This equates to a 500-fold increase in tunneling selectivity for holes over electrons, for a film thickness of 3 nm. However, the thickness of such films increases by 2 Å–5 Å within 48 h in cleanroom conditions, which leads to a reduction in hole-selectivity. X-ray photoelectron spectroscopy depth profiling has shown this film growth to be linked to oxidation, and furthermore, it alters the ΔEC/ΔEVratio to 1.22 ± 0.18. The SiNx/Si interface band alignment makes SiNxnanolayers a promising architecture to achieve widely sought hole-selective passivating contacts for high efficiency silicon solar cells. |
| Databáze: | OpenAIRE |
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