Atomic layer deposition of ZnO on thermal SiO2 and Si surfaces using N2-diluted diethylzinc and H2O2 precursors

ZnO nanodots are attracting more and more attention in various photoelectrical applications due to multiple excition generation. In this article, atomic layer deposition (ALD) growth of ZnO nanodots has been realized for the first time on both thermal SiO2 and Si surfaces using N2-diluted gaseous DEZn and H2O2 precursors. The experimental results indicate that the ALD ZnO exhibits a nano-crystalline film with corrugated surfaces in the case of the deposition temperature of 200 °C, likely due to concrescence among ZnO nanodots. When the deposition temperature is increased up to 300 °C, ZnO is grown in the form of well-discrete nanodots. This is due to increased desorption of the reacting molecules and a reduction of nucleation sites on the growing surfaces at 300 °C, thus leading to the reaction between DEZn and OH groups only on some favorable sites from thermodynamic and energy points of view. In terms of the thermal SiO2 surface, ZnO nanodots with a density of around 5 × 1010 cm−2 are obtained for 100 cycles. As for the Si surface, ZnO nanodots with a density as high as ∼1 × 1011 cm−2 are achieved for 50 cycles. Finally, the X-ray photoelectron spectroscopy and X-ray diffraction analyses reveal that the ALD ZnO at 300 °C is dominated by ZnO bonds together with a small quantity of ZnOH bonds, and the deposition temperature of 300 °C can result in preferential growth of ZnO (0 0 2) orientation and a bigger crystallite size.

► ZnO nanodots were grown first on SiO2 and Si surfaces by ALD. ► Influence of deposition-temperature and reaction-cycles on ZnO was studied. ► The mechanisms related to different ZnO morphologies were addressed. ► The composition and crystallinity of ZnO was characterized by XPS and XRD.