Kazuhiri Gotoh

Si-based Nanostructures

Nagoya University, Nagoya, Japan,

Email: gotoh.kazuhiro@material.nagoya-u.ac.jp

Abstract for Presentation

Silicon nanocrystals in silicon oxide matrix for passivating contacts in crystalline silicon solar cells

   We report on our recent progress in development of the NAnocrystalline Transport Path in Ultra-thin dielectrics for Reinforced passivation (NATURE) contact, which could simultaneously achieve high passivation performance, low contact resistance, and long-term reliability for various devices including solar cells [1]. The NATURE contact consists of silicon nanocrystals embedded in amorphous silicon oxide matrix. The silicon nanocrystals act as carrier transport pathways, which leads to a low contact resistance.

   Figure 1 shows a cross-sectional transmission electron microscope (TEM) image of a NATURE contact, and the inset is the electron diffraction pattern of a Si-NC in its SiOx layer. Fringes were observed in the locations indicated by a white circle. From the diffraction pattern, the lattice spacing was calculated as 3.12 Å, which is close to that of Si(111), proving that Si-NCs are formed in the SiOx. The amorphous silicon oxide and additional post treatment to introduce hydrogen atoms could chemically passivate the heterointerface to result in high passivation performance. Figure 2 shows the effective lifetime (τeff) of NATURE contact samples before and after hydrogen plasma treatment (HPT) as a function of minority carrier density (MCD). The maximum τeff increased from 524 μs to 1437 μs after HPT, indicating improved passivation performance. Furthermore, reasonably low specific contact resistance of 25~28 mΩ·cm2 was obtained after HPT. Thus, the NATURE contact can simultaneously realize high passivation performance and low specific contact resistance.

References

[1] R. Gong, L. Zheng, P. Roca i Cabarrocas, W. Chen, physica status solidi (RRL) – Rapid Research Letters, 16 (2022) 2100554.

[2] L. Zheng, E. Azrak, R. Gong, C. Castro, S. Duguay, P. Pareige, P. Roca i Cabarrocas, W. Chen, Journal of Alloys and Compounds, 899 (2022) 163273.

[3] E. Azrak, W. Chen, S. Moldovan, S. Gao, S. Duguay, P. Pareige, P. Roca i Cabarrocas, The Journal of Physical Chemistry C, 122 (2018) 26236-26242.

[4] E. Azrak, W. Chen, S. Moldovan, S. Duguay, P. Pareige, P. Roca i Cabarrocas, The Journal of Physical Chemistry C, 124 (2020) 1220-1226.

[5] R. Gong, E. Azrak, C. Castro, S. Duguay, P. Pareige, P. Roca i Cabarrocas, W. Chen, Nanotechnology, 32 (2021) 345602.

[6] R. Cariou, W. Chen, I. Cosme-Bolanos, J.-L. Maurice, M. Foldyna, V. Depauw, G. Patriarche, A. Gaucher, A. Cattoni, I. Massiot, S. Collin, E. Cadel, P. Pareige, P. Roca i Cabarrocas, Progress in Photovoltaics: Research and Applications, 24 (2016) 1075-1084.

[7] J. An, Z. Zheng, R. Gong, T.B.T. Nguyen, H. Jun, M. Chrostowki, J.-L. Maurice, W. Chen, P. Roca i Cabarrocas, Applied Surface Science, 518 (2020) 146057.

[8] J. An, J.-L. Maurice, V. Depauw, P. Roca i Cabarrocas, W. Chen, Applied Surface Science, 546 (2021) 149056.

[9] W. Chen, R. Cariou, G. Hamon, R. Léal, J.-L. Maurice, P. Roca i Cabarrocas, Scientific Reports, 7 (2017) 43968.

[10] W. Chen, J.-L. Maurice, J.-C. Vanel, P. Roca i Cabarrocas, Journal of Physics D: Applied Physics, 51 (2018) 235203.

[11] W. Chen, G. Hamon, R. Léal, J.-L. Maurice, L. Largeau, P. Roca i Cabarrocas, Crystal Growth & Design, 17 (2017) 4265-4269.

Figure 1. Cross-sectional TEM image of the NATURE contact. The inset is the electron diffraction pattern of a Si-NC in the SiOx layer.

Figure 2. Effective lifetime before and after hydrogen plasma treatment as a function of MCD.