[11p-W321-1~14] 13.9 Compound solar cells

[11p-W321-11] Semiconductor Wafer Bonding Mediated by Solution-Processed ZnO TCO

〇Tatsushi Yamashita¹, Soichiro Hirata¹, Kodai Kishibe¹, Ryoichi Inoue¹, Katsuaki Tanabe¹ (1.Kyoto Univ.)

Keywords:transparent conductive oxide, semiconductor wafer bonding, multijunction solar cells

Semiconductor wafer direct bonding is a promising scheme to fabricate high-crystalline-quality, high-efficiency lattice-mismatched multijunction solar cells, in contrast to the conventional heteroepitaxial growth. However, the wafer surface condition for direct bonding is severely restricted, for surface roughness and particulates worsen interfacial stability and conductivity. Wafer bonding mediated by transparent conductive oxides (TCOs) is a promising alternative. In this study, we adopted spin-coated ZnO as a TCO, because of its low cost, earth-abundance, and environmental friendliness. In contrast to the direct bonding scheme, such a solution-based TCO bonding approach provides a practical advantage of significantly larger tolerance for surface roughness and particulates to mitigate the growth condition requirements, thanks to the deformable interfacial contact agent to be solidified in the bonding process.