Synthesis, structures and optical properties of CdS:Cd/Si multi-interface nanoheterojunction

•CdS:Cd/Si-NPA is synthesized through a chemical bath deposition method.•Cd2+ are deoxidized, Cd nanocrystals are incorporated into the interface of Si–CdS.•Through analyzing the XPS spectrum of Cd 3d, the ratio of Cd0 to Cd2+ is about 0.7:1.•Three primary color emissions from CdS:Cd/Si-NPA are obtained.

CdS/Si multi-interface nanoheterojunction is synthesized through depositing nanocrystals CdS (nc-CdS) on the silicon nanoporous pillar array (Si-NPA) using a chemical bath deposition method. p-type nanocrystals Si in Si-NPA and n-type nc-CdS construct the multi-interface nanoheterojunction. Due to the reducibility of Si-NPA, a portion of Cd2+ in the interface of Si-NPA and solution are deoxidized and nanocrystals Cd are simultaneously incorporated into the interface of Si–CdS, namely, CdS:Cd/Si-NPA. Through decomposing the resolution XPS spectrum of Cd 3d, the ratio of Cd0 and Cd2+ is about 0.7:1. Three primary color emissions from CdS:Cd/Si-NPA are observed at the room temperature. Optical band gap obtained by the Tauc’s relation and origins of emission bands are studied.