[15p-A403-1~16] 13.2 Exploratory Materials, Physical Properties, Devices

▲ [15p-A403-10] Application of a-SiC Electron Transport Layer in BaSi₂ Solar cells

〇(D)Rui Du¹, Sho Aonuki¹, Hayato Hasebe¹, Kazuki Kido¹, Haruki Takenaka¹, Masami Mesuda², Kaoru Toko³, Takashi Suemasu³ (1.Univ. of Tsukuba, Graduate School of Science and Technology, 2.Tosoh Corp., Advanced Materials Research Laboratory, 3.Univ. of Tsukuba, Faculty of Pure and Applied Sciences)

Keywords:BaSi2, SiC, solar cell

Barium disilicide (BaSi₂) is a potential solar cell material. Currently, most BaSi₂ solar cells are constructed on wafer-based Si substrates. It is of great importance to form it on inexpensive substates like SiO₂. The sputter-deposited BaSi₂ films on TiN/SiO₂ showed high photoresponsivity exceeding 1 A/W. This result shows the feasibility of n-BaSi₂ as a light absorber layer on a cheap TiN/SiO₂ substrate. It should be noted that a Schottky barrier height may theoretically be formed when BaSi₂ and TiN are in direct contact. Actually, due to the defects at the interface, it didn’t have such a high Schottky barrier height because the high photoresponsivity has been obtained. The defect level and density of n-BaSi₂/TiN are not yet clear. It is necessary to optimize the n-BaSi₂/TiN interface.
Sputtered a-SiC has a band gap of 2.0 eV and a small qχ of 3.5 eV close to that of BaSi₂, confirming the passivation effect on BaSi₂. Thus a-SiC can be an ideal choice of electron transport layer (ETL) inserted between n-BaSi₂/TiN. We chose p⁺-BaSi₂ as the hole transport layer to solve the problem of the band offset between the BaSi₂-based pn junction. The role of a-SiC as an ETL in p⁺-BaSi₂/n-BaSi₂/a-SiC/TiN has been confirmed by AFORS-HET. The J-V characteristics of the device are also significantly improved by the a-SiC by AFORS-HET. We have every reason to believe that a-SiC is a suitable ETL material with great application potential for BaSi₂-based solar cells. We will further verify and optimize the ETL function of a-SiC in subsequent experiments to achieve device performance comparable to the simulation results.