Polarity-Free Resistive Switching Characteristics of CuxO Films for Non-volatile Memory Applications

Resistive switching characteristics of CuxO films grown by plasma oxidation process at room temperature are investigated. Both bipolar and unipolar stable resistive switching behaviours are observed and confirmed by repeated current voltage measurements. It is found that the RESET current is dependent on SET compliance current. The mechanism behind this new phenomenon can be understood in terms of conductive filaments formation/rupture with the contribution of Joule heating.     

Artificial Modulation of Ferroelectric Thin Films into Antiferroelectric through H+ Implantation for High-Density Charge Storage

Hydrogen ions are implanted into Pb（Zro.3Tio.7）03 1014 ions/cm^2. Pseudo-antiferroelectric behaviour in thin films at the energy of 40keV with a flux of 5 x the implanted thin films is observed, as confirmed by the measurements of polarization versus electric hysteresis loops and capacitance versus voltage curves. X-ray diffrac- tion patterns show the film structures before and after H＋ implantation both to be perovskite of a tetragonal symmetry. These findings indicate that hydrogen ions exist as stable dopants within the films. It is believed that the dopants change domain-switching behaviour via the boundary charge compensation. Meanwhile, time dependence of leakage current density after time longer than lOs indicates the enhancement of the leakage cur- rent nearly in one order for the implanted film, but the current at time shorter than i s is mostly the same as that of the original film without the ionic implantation. The artificial tailoring of the antiferroelectric behaviour through H＋ implantation in ferroelectric thin films is finally proven to be achievable for the device application of high-density charge storage.     

Thermal Stability of Reliable Polycrystalline Zirconium Oxide for Nonvolatile Memory Application

Thermal stability of resistive switching of stoichiometric zirconium oxide thin films is investigated for high yielding nonvolatile memory application. The A1/ZrO2/AI cell fabricated in the conventional device process shows highly reliable switching behaviour between two distinct stable resistance states. The retention capabilities are also tested under various conditions and temperatures. The excellent performance of Ai/ZrO2/AI ceil can be explained by assuming that anode/ZrO2 interface exists and by conducting filament forming/rupture mechanism. The device failure is illustrated in terms of permanent conducting filaments formation.     

Quantum-Mechanical Study on Surrounding-Gate Metal-Oxide-Semiconductor Field-Effect Transistors

As the channel length of metal-oxide-semiconductor field-effect transistors （MOSFETs） scales into the nanometer regime, quantum mechanical effects are becoming more and more significant. In this work, a model for the surrounding-gate （SG） nMOSFET is developed. The SchrSdinger equation is solved analytically. Some of the solutions are verified via results obtained from simulations. It is found that the percentage of the electrons with lighter conductivity mass increases as the silicon body radius decreases, or as the gate voltage reduces, or as the temperature decreases. The eentroid of inversion-layer is driven away from the silicon-oxide interface towards the silicon body, therefore the carriers will suffer less scattering from the interface and the electrons effective mobility of the SG nMOSFETs will be enhanced.     

溶剂辅助蒸馏-气相色谱-串联质谱法分析酿酒葡萄中的游离态萜烯类化合物

应用气相色谱-串联质谱联用技术(GC-MS/MS)和溶剂辅助蒸馏技术(SAFE)对4种酿酒葡萄中的游离态萜烯类化合物进行了研究。采用恒温振荡法浸提葡萄中的成分,溶剂辅助蒸馏法除去不挥发性成分,提取液经氮吹浓缩后进行GC-MS/MS分析。实验中优化了SAFE条件(循环水浴温度、样品流量)。通过NIST05a谱库检索、标准品的保留指数（RI值）对比及参考文献的RI值对比分析，在4种葡萄中共鉴定出30种萜烯类化合物,其中包括10种单萜烯类化合物、18种倍半萜烯类化合物、1种二萜烯类化合物以及1种三萜烯类化合物。在蛇龙珠葡萄中检出了28种萜烯类化合物,在梅鹿辄、赤霞珠和品丽珠葡萄中分别检出了16，17和16种萜烯类化合物。在蛇龙珠葡萄中检出了17种倍半萜烯类化合物,远多于其他3种酿酒葡萄。通过半定量分析，发现在赤霞珠葡萄中单萜烯类化合物含量较高,在蛇龙珠葡萄中倍半萜烯化合物含量较高。实验结果表明,该方法适用于酿酒葡萄中游离态萜烯类成分的定性和定量分析。     

氮掺杂Ge2Sb2Te5相变存储器的多态存储功能

通过反应溅射的方法,制备了N掺杂的Ge2Sb2Te5(N-GST)薄膜,用作相变存储器的存储介质.研究表明,掺杂的N以GeN的形式存在,不仅束缚了Ge2Sb2Te5 (GST)晶粒的长大也提高了GST的晶化温度和相变温度.利用N-GST薄膜的非晶态、晶态面心立方相和晶态六方相的电阻率差异,能够在同一存储单元中存储三个状态,实现相变存储器的多态存储功能.