Search

The electrical leakage current of thin rutile structured TiO2 films deposited by atomic layer deposition on a Ru electrode was enormously reduced by depositing an extremely thin HfO2 (< 1 nm) on top. The sacrifice of the capacitance density by the HfO2 was minimized. The leakage mechanism analysis on the Pt/TiO2/Ru and Pt/HfO2/TiO2/Ru structures revealed that the improvement in leakage current was attributed to the reduction of defect (trap) density in the TiO2 film. The interfacial potential barrier height for electron transport in thinner (∼ 10 nm) TiO2 films was lower than that of thicker (∼ 20 nm) TiO2 films, which resulted in a higher leakage current in these films. The capping of ultra-thin (∼ 0.7 nm) HfO2 films effectively increased the potential barrier height, and the leakage current was decreased accordingly. The leakage current behavior was systematically analyzed from quantum mechanical transport simulations. [ABSTRACT FROM AUTHOR]

Abstract: The electrical and structural properties of HfO2 films on Si1−x Ge x substrates with various Ge concentrations (x =0.1, 0.2, 0.3) were investigated. The behavior of Ge in the interfacial layer (IL) and its effects on the electrical and structural properties after post-annealing were studied in detail. The Ge of the substrate degrades the interfacial properties by interfacial reaction during HfO2 ALD. It also plays an important role in reducing the capacitance equivalent thickness and hysteresis after post-annealing. The improvements in the electrical properties originated from IL thinning due to a drive-out of Ge from the IL and the increase in permittivity of the HfO2 layer due to Hf-Ge-oxide formation. [Copyright &y& Elsevier]

Abstract: This study investigated the atomic layer deposition (ALD) behavior of zinc oxide (ZnO) films on SiO2/Si substrates using Zn(C2H5)2 and O3 as the precursor and oxidant, respectively, at substrate temperatures ranging from 230 to 300 °C, and the electrical properties of the thin films. The self-limiting ALD mechanism of ZnO thin film growth was confirmed in the whole temperature region, and the growth rate decreased from 0.19 nm/cycle at 230 °C to 0.16 nm/cycle at 300 °C. ZnO films with a c-axis preferential orientation were obtained at these relatively low temperatures. The films contained a lower oxygen concentration compared to the films grown with the same precursor and H2O oxidant. However, the ZnO film grown with the O3 oxidant at 300 °C showed approximately a resistivity three orders of magnitude higher than that of the ZnO film using the H2O oxidant, due to higher Si impurity concentration in the ZnO films. Si diffusion into the ZnO films must be due to the stronger oxidation power of O3 compared to H2O. [Copyright &y& Elsevier]