This book focuses on fabrication of ZnO/CdS optical sensor. Nanocrystalline ZnO/CdS core-shell optical sensors were fabricated by chemical bath deposition (CBD) method. Vertically aligned ZnO nanorods were firstly synthesized on silicon p-type (111) by CBD method with assist of microwave. The CdS were deposited on the ZnO nanorods to create core-shell structure by using CBD method with cadmium chloride (CdCl2) 0.15M as Cd2+ ion source at difference deposition time. ZnO nanorods were the core and CdS were the shell of this core-shell structure. The photoconductive testing was carried out to...