Optoelectronic properties of cauliflower like ZnO–ZnO nanorod/p-Si heterostructure

The cauliflower like ZnO nanostructures are grown on ZnO nanorods using spray pyrolysis method. First, ZnO nanorod arrays are grown on p-type silicon substrate without catalyst by chemical vapor transport and condensation method in a horizontal tube furnace. Afterwards, the cauliflower like ZnO nanostructures is deposited on top of the ZnO nanorod array. The PL spectra of cauliflower like ZnO nanostructures consist of UV emission bands around 387 nm and a visible emission at ∼440 nm. The current–voltage (I–V) measurement under dark and UV illumination condition are performed to study photodetection of the cauliflower like ZnO–ZnO nanorod/p-Si heterostructure. The experimental data of dark I–V curve show that the tunneling-recombination model is the dominant current transport mechanism in our device heterostructure below 2 V. It is observed that UV photons are absorbed in ZnO and device exhibit 0.07 A/W responsivity at 5 V reverse bias which correspond to quantum efficiency of 26%.

► ZnO nanorods. ► Cauliflower. ► Transport mechanism. ► Photoresponse properties.