One step to fabricate vertical submicron ZnO rod arrays by hydrothermal method without seed layer for optoelectronic devices

Reducing production cost by minimizing growth steps of ZnO microstructures is an important key for large scale fabrication of optoelectronic devices. Here, we present the growth of submicron ZnO arrays on FTO substrates by only one step without seed layers using hydrothermal method. The effect of KOH mass concentration on the physical properties of ZnO submicron rods has been investigated employing Uv-vis spectroscopy, X-ray diffraction, and scanning electron microscopy. The results indicate the formation of hexagonal structure of ZnO submicron arrays with different surface morphology, different orientations and diameters dependent on KOH concentration. Uniform ZnO submicron rod arrays with (0 0 2) preferred orientation were obtained when the KOH concentration was 0.24 g/ml. Beside the uniformity and good alignment of ZnO arrays along the c-axis of FTO substrate, they have the smallest diameter which make them suitable to photo-electronic applications.