Han Dedong

Improved Resistive Switching Characteristics of Ag-Doped ZrO2 Films Fabricated by Sol-Gel Process

Ag-doped and pure ZrO2 thin films are prepared on Pt/Ti/SiO2/Si substrates by sol-gel process for resistive random access memory application. The highly reproducible resistive switching is achieved in the 10% Ag-doped ZrO2 devices. The improved resistive switching behaviour in the Ag doped ZrO2 devices could be attributed to Ag doping effect on the formation of the stable filamentary conducting paths. In addition, dual-step reset processes corresponding to three stable resistance states are observed in the 10% Ag doped ZrO2 devices, which may be implemented for the application of multi-bit storage.

Fabrication and characteristics of high-K HfO2 gate dielectrics on n-germanium

This paper reports that the high-K HfO2 gate dielectrics are fabricated on n-germanium substrates by sputtering Hf on Ge and following by a furnace annealing. The impacts of sputtering ambient, annealing ambient and annealing temperature on the electrical properties of high-K HfO2 gate dielectrics on germanium substrates are investigated. Experimental results indicate that high-K HfO2 gate dielectrics on germanium substrates with good electrical characteristics are obtained, the electrical properties of high-K HfO2 gate dielectrics is strongly correlated with sputtering ambient, annealing ambient and annealing temperature.

Annealing characteristics of ultra-thin high-K HfO2 gate dielectrics

Ultra-thin HfO2 gate-dielectric films were fabricated by ion-beam sputtering a sintered HfO2 target and subsequently annealed at different temperatures and atmospheres. We have studied the capacitance-voltage, current-voltage and breakdown characteristics of the gate dielectrics. The results show that electrical characteristics of HfO2 gate dielectric are related to the annealing temperature. With increase annealing temperature, the largest value of capacitance decreases, the equivalent oxide thickness increases, the leakage current reduces and the breakdown voltage decreases.

Reactive Radiofrequency Sputtering-Deposited Nanocrystalline ZnO Thin-Film Transistors

The structural and electrical properties of ZnO films deposited by reactive radiofrequency sputtering with a metallic zinc target are systematically investigated. While the as-deposited ZnO film is in a poly-crystalline structure when the partial pressure of oxygen (pO2) is low, the grain size abruptly decreases to a few nanometers as pO2 increases to a critical value, and then becomes almost unchanged with a further increase in pO2. In addition, the resistivity of the ZnO films shows a non-monotonic dependence on pO2, including an abrupt transition of about seven orders of magnitude at the critical pO2. Thin-film transistors (TFTs) with the nanocrystalline ZnO films as channel layers have an on/off current ratio of more than 107, an off-current in the order of pA, a threshold voltage of about 4.5 V, and a carrier mobility of about 2cm2/(V?s). The results show that radiofrequency sputtered ZnO with a zinc target is a promising candidate for high-performance ZnO TFTs.