Title:	In-depth Exposure of New Phase in Poly-Silicon of TOPCon Device: Is Phosphorus Bonded Oxygen Present?
Author(s):	Z.Q. Ma, Y.L. Wang, Z.X. Lan
Keywords:	XPS Profile, TOPCon Device, Poly-Si Film, P-O Bonds, Thermodynamic Analysis
Topic:	Silicon Materials and Cells
Subtopic:	Characterisation & Simulation of Si Cells
Event:	8th World Conference on Photovoltaic Energy Conversion
Session:	1DV.4.4
Pages:	159 - 164
ISBN:	3-936338-86-8
Paper DOI:	10.4229/WCPEC-82022-1DV.4.4
Price:	0,00 EUR
Document(s):	paper

Abstract/Summary:

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For the TOPCon PV device, the heavy phosphorus (P) – doped polycrystalline silicon layer (n+-poly-Si) with ultra-thin silicon oxide (a-SiOx) is extremely beneficent for passivating contact and electron selectivity as its exceptional coupled microstructure (chemical components and physical phase) and optoelectric properties, compared with other passivation materials. However, an unknown configuration of oxygen (O) and phosphorus (P) in the n+-poly Si film is still open for investigation. The findings of the P-O bonds (bridge and non-bridge linkages) in the whole scope of n+-poly Si film have been implemented by X-ray photoelectron spectroscopy (XPS) in the mode of depth profile measurements of P 2p, O 1s, and Si 2p states. The symbolic binding energies (BEs) with a shoulder in the range of 126 – 142 eV for the P 2p state and the other two photon-emission peaks of the O 1s state centered at 532 and 535 eV, respectively, were obtained by an occasional survey of SiOx composition. Furthermore, the Grazing incidence Xray diffraction (GIXRD) measurements of the n+-poly Si films showed that the typical nano-crystallinity with grain sizes of 38-45 nm is obtained. The derivatives of oxidized phosphorite localized at grain boundaries (GBs) were tentatively analyzed through thermodynamic functions. In addition, the segregation of P and O compositions was detected by energy dispersive X-ray (EDX) patterns for the surface-textured (pyramid) wafer, while there is no segregation of elements or compounds in the planar n+-poly Si film.