Surface preparation passivation and patterning techniques used in silicon based heterojunction solar cells

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Tezin Türü: Yüksek Lisans

Tezin Yürütüldüğü Kurum: Orta Doğu Teknik Üniversitesi, Fen Edebiyat Fakültesi, Fizik Bölümü, Türkiye

Tezin Onay Tarihi: 2017

Öğrenci: ERGİ DÖNERÇARK

Danışman: RAŞİT TURAN

Açık Arşiv Koleksiyonu: AVESİS Açık Erişim Koleksiyonu

Özet:

For silicon Heterojunction (SHJ) solar cell technology features, a thin intrinsic hydrogenated amorphous silicon (i a-Si:H) layer has inserted between the crystalline silicon and doped amorphous silicon. The state of the art SHJ solar cell structure involves low temperature depositions of a-Si:H layer by means of Plasma Enhanced Chemical Vapor Deposition (PECVD) technique. Recent developments on SHJ solar cells have been focused on increasing the passivation quality of a-Si:H layer and the formation of all metal contacts on the rear side. In this thesis, the motivation is to achieve high efficiency SHJ solar cells by improving the surface passivation properties of thin a-Si:H film together with the integration of interdigitated back contact (IBC) concept. In this study, several surface preparation techniques including wet chemical chemistry were implemented to solar cell fabrication sequence. The wet chemical processes were optimized to reach the required surface cleanness appropriate for device applications. Additionally, the effects of the pyramid edge rounding process were investigated on the optical and electrical properties of the solar cell. Then, the deposition parameters of i a-Si:H were optimized to enhance surface passivation. Furthermore, the optimum post-annealing treatment parameters were determined to improve the sputtering induced damages. Consequently, the highest efficiency was recorded as 12.5% and 15.8% for the samples with the cell area of 4 cm2 and 0.9 cm2, respectively. In addition, a novel wet chemical etching approach for emitter patterning was utilized in the fabrication of SHJ IBC solar cell. Moreover, for the emitter etching process, the optimized wet chemical chemistry and application conditions were demonstrated in term of the passivation quality of the etched areas. The passivation quality of a-Si:H/silicon nitride (SiNX) stack layer was also investigated as a front surface passivation and antireflection layer by combining with the etching method in SHJ IBC fabrication sequence. As a result of the successful application of the optimized process parameters, the production of 18% efficient SHJ IBC solar cells was realized without any surface texturing.