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Two highly orderd CdS/Si-NPA heterostructures were fabricated by in situ synthesis of cadmium sulphide (CdS) nanoparticles via a simple polyphase reaction on the base of a well-aligned silicon nanoporous pillar array (Si-NPA).One was cap-like structure with only a weak CdS concentration gradient from the top to the bottom of Si pillars,and the other was pole-like structure with a strong CdS concentration gradient,which were decided by varying the ultraviolet (UV) irradiation condition.The characteristices of the CdS/Si-NPA heterostructures were then analyzed contrastively.X-ray photoelectron spectroscopy and energy dispersive x-ray analysis confirmed the presence of CdS on the surfaces of two Si-NPAs and also gave the evidences of CdS nanoparticles growth with highly selection.The photoluminescence intensities for two typies of heterostructures were all observed to increase by more than two factors and were associated with a blue shift.The increase of intensities originated new radicative recombination centries and the blue shift was indicative of surface state modidicative of Si-NPA.