Chemical stoichiometry effect of hafnium oxide (HfOx) for passivation layer of PERC solar cells

Kim, Jaeun; Ju, Minkyu; Kim, Young-Kuk; Yi, Junsin

doi:10.1016/j.mssp.2022.106833

Cited by 7 publications

(3 citation statements)

References 25 publications

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“…2(c), with a value of 37.1 fA/cm 2 at 475 °C and a minimum of 28.4 fA/cm 2 at 500 °C. There is a lack of direct reporting of J 0 values for HfO 2 passivated surfaces in the literature, but one recent paper reports values an order of magnitude higher than ours [27].…”

Section: A Variation Of Activation Annealing Conditionscontrasting

confidence: 68%

Mechanisms of Silicon Surface Passivation by Negatively Charged Hafnium Oxide Thin Films

Wratten

Pain

Walker

et al. 2023

IEEE J. Photovoltaics

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We have studied the mechanisms underpinning effective surface passivation of silicon with hafnium oxide (HfO 2 ) thin films grown via atomic layer deposition (ALD). Plasma-enhanced ALD with O 2 plasma and a tetrakis(dimethylamido)hafnium precursor was used to deposit 12 nm thick HfO 2 films at 200 °C on high-lifetime 5 Ωcm n-type Czochralski silicon wafers. The passivation was activated by postdeposition annealing, with 30 min in air at 475 °C found to be the most effective. High-resolution grazing incidence X-ray diffraction measurements revealed the film crystallized between 325 and 375 °C, and this coincided with the onset of good passivation. Once crystallized, the level of passivation continued to increase with higher annealing temperatures, exhibiting a peak at 475 °C and yielding surface recombination velocities of <5 cm s −1 at 5 × 10 14 cm −3 injection. A steady decrease in effective lifetime was then observed for activation temperatures >475 °C. By superacid repassivation, we demonstrated this reduction in lifetime was not because of a decrease in the bulk lifetime, but rather because of changes in the passivating films themselves. Kelvin probe measurements showed the films are negatively charged. Corona charging experiments showed the charge magnitude is of order 10 12 qcm −2 and that the reduced passivation above 475 °C was mainly because of a loss of chemical passivation. Our study, therefore, demonstrates the development of highly charged HfO 2 films and quantifies their benefits as a standalone passivating film for silicon-based solar cells.

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Section: A Variation Of Activation Annealing Conditionscontrasting

confidence: 68%

Mechanisms of Silicon Surface Passivation by Negatively Charged Hafnium Oxide Thin Films

Wratten

Pain

Walker

et al. 2023

IEEE J. Photovoltaics

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“…Passivation helps to reduce surface recombination, improving the efficiency of solar cells by extending the lifetime of photo-generated carriers. The application of HfO x as a passivation layer on the rear surface will help in minimizing losses due to carrier recombination and will enhance the performance of the solar cell [55,59,60]. While the HfO x layer adds thickness to the overall solar cell structure, the benefits in terms of improved passivation and carrier lifetime may outweigh the thickness aspect.…”

Section: Capacitance -Voltage Measurementmentioning

confidence: 99%

Effect of films thickness and hydrogen annealing on passivation performance of plasma ALD based Hafnium oxide films

Devi,

Tomer,

Pathi

et al. 2024

Phys. Scr.

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We investigate the silicon surface passivation property of Plasma Atomic Layer Deposited (PALD) hafnium oxide (HfOx) thin films and study its dependence on silicon (Si) doping type, film thickness, and post-deposition annealing conditions. Our results demonstrate that as-deposited HfOx films exhibit poor passivation quality that can be improved by performing post-deposition annealing at 450℃ in hydrogen ambient. We demonstrate that the films can effectively passivate p-Si surfaces as compared to n-Si, where the surface passivation quality of the films improves with increasing film thickness for both silicon doping type. The best performance with minority carrier lifetime of 1.7 ms, corresponding surface recombination velocity (SRV) ~10 cm/s, is achieved for HfOx films thickness ~23 nm deposited on the p-Si substrate. The Capacitance-Voltage (C-V) measurements give an insight into the passivation mechanism of the studied films. Field effect passivation is found to be an important passivation mechanism in plasma ALD deposited HfOx films, as revealed by C-V measurements. The films are also characterized using Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS), which reveals the chemical passivation provided by hydrogen ambient annealing. Overall, the impact of hafnium oxide film thickness and hydrogen ambient annealing conditions on silicon surface passivation is investigated. Our findings will help in utilizing plasma ALD process based hafnium oxide films for silicon solar cell device application.

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“…Based on this technology, the PCE of PERC solar cells has been improved from 21.4% to 24.06%, which approaches the theoretical limit. 7 At present, while other solar cell technologies have not made major breakthroughs, PERC solar cells will still maintain a dominant position in the market for a certain period of time. 6 In the manufacturing of solar cells, blistering of the SiN x layer on the rear of the solar cells can restrict the PCE improvement and the yield on the industrial production line.…”

mentioning

confidence: 99%

Suppressing The Blistering of Silicon Nitride in PERC Solar Cells for High Industrial Yield

Zhu,

Lei,

Gao

et al. 2024

ECS J. Solid State Sci. Technol.

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Passivated emitter and rear contact (PERC) solar cells possess the highest photovoltaic market share at present. In industrial production, blistering of the rear silicon nitride (SiNx) passivation layer significantly affects the yield. In order to solve this problem, the relevant processes for manufacturing the PERC solar cells have been carefully studied. It was found that polishing of the silicon wafer rear surface, aluminum (AlOx) thickness, and the deposition process of the SiNx layer will affect the blistering ratio. By optimizing the manufacturing process mentioned above, the blistering ratio of the PERC solar cells has been effectively suppressed. This work not only provides reliable technical support for the yield improvement of the PERC solar cells but also provides some useful reference for the tunnel oxide passivated contact (TOPcon) and back contact (BC) solar cell industrial manufacture

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Chemical stoichiometry effect of hafnium oxide (HfOx) for passivation layer of PERC solar cells

Cited by 7 publications

References 25 publications

Mechanisms of Silicon Surface Passivation by Negatively Charged Hafnium Oxide Thin Films

Mechanisms of Silicon Surface Passivation by Negatively Charged Hafnium Oxide Thin Films

Effect of films thickness and hydrogen annealing on passivation performance of plasma ALD based Hafnium oxide films

Suppressing The Blistering of Silicon Nitride in PERC Solar Cells for High Industrial Yield

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