Ultraviolet electroluminescence from flowers-like n-ZnO nanorods/p-GaN light-emitting diode fabricated by modified chemical bath deposition

In this work, an ultraviolet (UV) light-emitting diode (LED) based on flowers-like n-ZnO nanorods (NEs)/p-GaN was fabricated using direct heat substrate-modified chemical bath deposition (DHS-MCBD) method. Initially, the ZnO nanoparticles were grown on the top of a p-type GaN substrate as a seed layer which facilitated the growth of high-density of ZnO nanorods in various directions. The current-voltage (I-V) characteristics of the fabricated LED device showed a rectifying behavior of ZnO NIFs/p-GaN heterojunction whereas the breakdown mechanism for the device was generated by the tunneling effect. The luminescence properties of the device were studied at room temperature (RT) by using electroluminescence (EL) technique. The back side EL spectrum of the device displayed a sharp UV emission peaks at 367 and 378 nm for GaN and ZnO respectively. On the other hand, the EL spectrum taken from the front side was composed of UV emission, near blue emission along with a broadband green emission. The EL emission for the device was also observed with the naked eye under normal light from both of its sides. The light emission mechanism and the waveguiding effect of the ZnO NRs have been discussed in this work.