Optimization of Silicon Heterojunction Interface Passivation on p‐ and n‐Type Wafers Using Optical Emission Spectroscopy

To increase the efficiency in p‐type wafer‐based silicon heterojunction (SHJ) technology, one of the most crucial challenges is the achievement of excellent surface passivation. Herein, chemical passivation techniques known for n‐type technology are successfully applied on p‐type float–zone (FZ) waf...

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Bibliographic Details
Published in:Physica status solidi. A, Applications and materials science Applications and materials science, 2022-03, Vol.219 (5), p.n/a
Main Authors: Özkol, Engin, Wagner, Philipp, Ruske, Florian, Stannowski, Bernd, Korte, Lars
Format: Article
Language:English
Subjects:
chemical passivation
Circuits
Crystallization
crystallization rate indexes
Electron energy
electron temperature indexes
Heterojunctions
Hydrogen plasma
Minority carriers
Nucleation
Optical emission spectroscopy
Optimization
Passivity
Plasma diagnostics
Silicon
silicon heterojunction solar cells
surface passivation
Wafers
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Summary:To increase the efficiency in p‐type wafer‐based silicon heterojunction (SHJ) technology, one of the most crucial challenges is the achievement of excellent surface passivation. Herein, chemical passivation techniques known for n‐type technology are successfully applied on p‐type float–zone (FZ) wafers, and wafer surface passivation quality is correlated with parameters from plasma diagnostics, namely crystallization rate and electron temperature indices. It is shown that plasma ignition at higher powers than deposition powers enhances effective minority carrier lifetimes τeff fourfold for p‐ (0.6–2.1 ms) and sixfold for n‐type (0.6–3.2 ms) wafers while giving opportunity to process under lower electron temperature indices during the nucleation phase. A subsequent hydrogen plasma treatment has a further beneficial effect on chemical passivation, leading to high effective minority carrier lifetimes of 4.5 and 3.1 ms, and implies open‐circuit voltages, i‐VOC, of 735 and 720 mV for p‐ and n‐type wafers, respectively. In particular, cell precursors built on p‐type wafers demonstrate excellent surface passivation with τeff and i‐VOC (4.1 ms and 745 mV). Using these process optimizations, SHJ cells on both p‐ and n‐type wafers are fabricated with efficiencies exceeding 21%. Herein, chemical passivation enhancement techniques are successfully applied on p‐ and n‐type float–zone wafers, and passivation properties are correlated with plasma diagnostics. In particular, higher plasma ignition powers give opportunity to manipulate the film nucleation phase, and boost effective minority carrier lifetimes significantly. This application reflects itself in PCEs exceeding 21% for both types of wafers.
ISSN:1862-6300
1862-6319
DOI:10.1002/pssa.202100511