By Nathaporn Promros, Ryūhei Iwasaki, Suguru Funasaki,Kyohei Yamashita and Tsuyoshi Yoshitake
Mesa structural n-type nanocrystalline (NC) FeSi2/p-type Si heterojunctions prepared by photolithography were evaluated as near-infrared photodiodes at room temperature. The effects of this structure on the heterojunction photodiode performances were studied. Their junction capacitance density and leakage current density were evidently reduced as compared with those of the normal structural photodiodes. The near-infrared light detection performance was investigated using a 1.31μm laser at room temperature. The detectivity was estimated to be 1.5×108 cm rootHz/W at a zero bias, which was clearly improved as compared with that of the normal structural photodiodes. This should be because interface states are reduced accompanied by the interface area reduction.