Black silicon with nanostructured surface formed by low energy helium plasma irradiation

• Published in: Applied surface science 2019-09, Vol.487, p.755-765
• Main Authors: Takamura, S., Aota, T., Iwata, H., Maenaka, S., Fujita, K., Kikuchi, Y., Uesugi, Y.
• Format: Article
• Language: English
• Subjects: Black silicon; Crystallinity; Helium plasma irradiation; Nanostructure; Solar cell
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2019.05.034

Black silicon formed by helium plasma irradiation has attractive surface morphologies in terms of solar cell fabrication, because it has good photon absorption property across the solar spectrum. It also does not need any masking process, which is sometimes employed in the fabrication of pyramid-like microstructures. Black silicon formed by helium plasma irradiation has potential not only for solar cell applications, but also in the fields of photonics, optics, and ultrasonic wave generation. Here, the nano-cone structure formation process, detailed observations of surface morphologies with TEM as well as SEM, the optimal He irradiation conditions, surface reflectivity over UV–visible-NIR wavelengths, and scattered light enhancement with Raman spectroscopy in addition to X-ray diffraction measurements were studied. Investigation of electronic properties is reported, including good resistivity of the Si black surface without an ITO electrode. •The present technique for black Si with good light absorption and Si crystallinity employs low energy He ion irradiation.•The optimal He irradiation conditions are clarified along with a number of surface characterization.•Low surface resistivity of black Si was found and shows a possibility of removal of transparent electrode for application to solar cell.