Influence of Exposure with Xe Radiation on Heterojunction Solar Cell a-SiC/c-Si Studied by Impedance Spectroscopy

The efficiency of heterostructures a-SiC/c-Si may be the same or even better in comparison with conventional silicon structures when suitable adjustment of technological parameters and adding other suitable layers such as... [ view full abstract ]

The efficiency of heterostructures a-SiC/c-Si may be the same or even better in comparison with conventional silicon structures when suitable adjustment of technological parameters and adding other suitable layers such as anti-reflective, passivation layers and anti-recombination contacts is done. Recently, the record efficiency of 25.6 % [1] was achieved on similar heterojunction structure, which makes this technology the most efficient among the silicon based solar cells. The main advantages of heterojunction formed amorphous SiC thin film and crystalline silicon compared to standard crystalline solar cell lie in high build-in voltage and thus a high open-circuit voltage [2].
In our previous papers assessment of the impact of neutrons and Xe ions induced damage of a-SiC/c-Si heterostructures without ITO film was done. ITO offers high transmittance and high conductance and simultaneously acts as a passivating and antireflection coating. A deterioration of properties of heterostructures (a-SiC/c-Si) due to irradiation is examined in our paper using impedance spectroscopy method. Irradiation of structures with Xe ions to total fluency (5x1011 cm-2) was performed at room temperature.
An example of the results – deformation of impedance spectra due to the irradiation of sample coated with ITO is shown in Fig. 1.
Xe ions induced damage is reflected in changes of AC equivalent circuit elements. AC equivalent circuit was proposed and verified using numerical simulations. Impedance spectra were also measured at different DC bias voltages due to a more detailed understanding correlation between ions induced damage and transport phenomenon in the heterostructure.
Acknowledgement
This work was supported by the Slovak Research and Development Agency under the contract No. APVV-0443-12 and by the Scientific Grant Agency of the Ministry of Education of the Slovak Republic and of the Slovak Academy of Sciences Project VEGA 1/0651/16.
References
[1] Masuko K, et al: Achievement of more than 25% conversion efficiency with crystalline silicon heterojunction solar cell. Photovoltaics, IEEE Journal, Vol. 6 20141433-5.
[2] S. Janz, S. Reber, W. Glunz, Proceedings of the 21st EUPVSEC, 660-663 (2006).