ZnO Nanorods Grown on p-GaN Using Hydrothermal Synthesis and Its Optoelectronic Devices Application

The ZnO nanorods with the length of 1-1.5 μm were deposited on p-GaN by hydrothermal synthesis at low temperature 100°C. The structural and optical properties of the as-grown ZnO rods were investigated by X-Ray diffraction (XRD) and photoluminescence (PL) spectra. After annealing treatment the as-grown films in air at 600°C, 30min, and the ZnO rods showed good crystallinity and optical properties with strong UV emission at 378 nm. In addition, a sharp UV emission peak at 369.45 nm with the FWHM 20 meV, which attributed to the bound exciton recombination, was also observed from the ZnO rods at 80K. Next, the e-beam evaporation method was used to deposit metal contact on n-ZnO and p-GaN. Here, we use Au and Ni/Au as metal contacts for n-ZnO and p-GaN, respectively. The current-voltage characteristics of the fabricated n-ZnO/p-GaN heterojunction revealed rectifying behavior with a leakage current of 10⁻⁸ A at -10V, a forward current 4x10⁻⁶ A at 10V bias. The heterojunction also showed a good photoresponse, with the change of the current – voltage characteristics under ultraviolet illumination. Under UV illumination, the forward turn on voltage changed to 7.5V. This result showed the ability to manipulate the electron transport in the ZnO based heterojunction devices.Singapore-MIT Alliance (SMA