Fabrication of tree-like CdS nanorods-Si pillars structure for photosensitive application

Recently, a kind of tree-like CdS nanorods-Si pillars structure were fabricated by hydrothermal method in our paper. The CdS nanorods tended to grow into branches with a diameter of 100 nm and a length of more than 500 nm, while the Si pillars tended to grow into trunks with an average diameter of 250–900 nm. The CdS nanorods were directly synthesized on the Si pillars surface with the glutathione served as a source of capping agent. During the reaction process, a seed layer of CdS film about 50 nm thickness was deposited on the Si pillars surface firstly, and then the CdS nanorods grew upon the seed layer. The XRD curves showed that the CdS nanorods with hexagonal morphology were well-crystallized on the Si pillars surface. Si pillars with different diameters and heights were used as substrates for CdS nanorods growth. As the CdS nanorods grow on the Si pillars, the reflectivity of all kinds of Si pillars were decreased to below 5% for wavelength ranging from 350–450 nm. The photoresistor of CdS nanorods on Si pillars with 900 nm average diameter and 2 μm height had the best photosensitivity performance under different illumination.