Defence of doctoral thesis in the field of Micro- and nanosciences, M.Sc.(Tech.) Ismo Rauha
M.Sc.(Tech.) Ismo Rauha will defend the thesis "Stability of silicon surface passivation under damp heat and light soaking" on22 Decenber 2021 at 12 in Aalto University School of Electrical Engineering, Department of Electronics and Nanoengineering, in lecture hall TU1, Maarintie 8, Espoo, and online in Zoom.
Opponent: Prof. Bram Hoex, UNSW Sydney (University of New South Wales), Australia
Custos: Prof. Hele Savin, Aalto University School of Electrical Engineering, Department of Electronics and Nanoengineering
In the defence arranged at campus, the organiser may check the COVID19 certificate of the participants, depending on the number of participants present (more details at: https://www.aalto.fi/en/study-at-aalto/being-a-doctoral-student-at-aalto --> Public defences).
Thesis available for public display at: https://aaltodoc.aalto.fi/doc_public/eonly/riiputus/
Doctoral theses in the School of Electrical Engineering: https://aaltodoc.aalto.fi/handle/123456789/53
The reliable and stable performance of crystalline silicon solar cells is vital in mitigating climate change, as they contribute to approximately 95% of all produced solar cells. During operation, solar cells are subjected to intense illumination, high temperatures, and high ambient humidity, which can be especially harmful for their surface passivation.
This thesis investigated the stability of silicon surface passivation under damp heat and light soaking as well as potential mechanisms behind the resulting degradation. As an important result it was demonstrated that 20-nm-thick aluminum oxide films provided stable surface passivation of both planar and nanotextured silicon for up to 1000 h of exposure to damp heat or light soaking. Additionally, the properties of the interfacial oxide between the surface passivation layer and the silicon surface were found to significantly influence the stability.
Surprisingly, also metal impurities in the silicon material itself had an impact on the surface passivation stability. A dramatic increase of surface recombination was observed in copper-contaminated silicon, indicating that impurities introduced into solar cells during their manufacturing process can influence their stability under field conditions.
In conclusion, this thesis brings insights on the stability of silicon surface passivation, which provides means to enhance the in-field performance of high-efficiency solar cells. These results are also applicable in the microelectronics and photodetector industries, in which strict process and impurity control to achieve stable surface passivation are vital for device performance.
Contact information of doctoral candidate: