The growth of ZnO on stainless steel foils by MOCVD and its application in light emitting devices.

Direct fabrication of semiconductor light emitting devices on metal foils is beneficial, because it brings flexibility and good heat sink in the devices. In this work, we have grown ZnO on the commercially available stainless steel foils by metal-organic chemical vapor deposition for the first time. With the increase of growth temperature, the morphology changes from a thin film structure to closely stacked columns, and eventually to nanorods. The change in the migration ability of adatoms due to the increase of growth temperature plays an important role in the evolution of morphology. The samples with nanorod morphology exhibit relatively better crystallinity and optical quality. A PEDOT: PSS/PMMA/ZnO device was fabricated based on the grown ZnO nanorods. The metal-insulator-semiconductor type device shows an uncommon symmetric I-V curve. Under reverse bias, the device emits fairly pure UV light, which comes from the near band edge emission of ZnO. The working mechanism of the devices has been discussed, and a model mainly based on the Poole-Frenkel effect is proposed to describe the charge transportation of the devices.