硫系相变材料Ge1Sb2Te4和Ge2Sb2Te5薄膜相变速度及电学输运性质研究

利用磁控溅射方法制备了Ge1Sb2Te4和Ge2Sb2Te5两种相变存贮材料的薄膜.原位X射线衍射(XRD)的结果表明,随着退火温度的升高,Ge1Sb2Te4和Ge2Sb2Te5薄膜都逐步晶化,材料结构发生了从非晶态到面心立方结构、再到六角密堆结构的转变.由衍射峰的半宽高可以看出,在达到第一次相变温度后,Ge2Sb2T...     

Thermoelectric Properties of Sb2Te3-Based Nanocomposites with Graphite

Semiconductors - Antimony-telluride-based nanocomposite samples containing different weight fractions of graphite (Sb2Te3 + x% graphite, where x = 0.0, 0.5, 1.0, and 2.5%) are synthesized and...     

Multilevel Recording in Ge2Sb2Te5 Thin Films

Semiconductors - The current–voltage characteristics measured on Ge2Sb2Te5 thin films in the current mode are studied. The effect of multilevel recording is established when applying...     

Electrode Materials for Ge2Sb2Te5-Based Memristors

The memristive characteristics of Ge₂Sb₂Te₅ (GST) as a representative chalcogenide material have been verified and show great potential for memory applications. This paper focuses on the influence of different electrode materials on the properties of GST-based memristors. Several electrode materials (Ti₃W₇, Ag, Cu, and Ta) were adopted in devices with a top electrode (TE)/GST/bottom electrode (BE) layer structure. Through different current–voltage (I–V) curves, it was demonstrated that devices with Ag or Cu electrodes are suitable for GST-based memristors, while those utilizing inert electrodes are not. Because of their relatively smaller radius and lower binding energy, it is much easier for Ag and Cu to diffuse into the GST layer and form conductive filaments. The results obtained from memristors annealed at different temperatures further support the conductive filament model. Moreover, an optimized Cu/Ag/GST/Cu device structure different from the traditional TE/GST/BE structure is proposed, showing improved stability with higher R _off/R _on ratio and good endurance.     

制备条件对Ge2Sb2Te5薄膜电学性能的影响

研究了磁控溅射制备Ge2Sb2Te5薄膜时,制备条件诸如功率、气压等对薄膜性能的影响.主要通过测量薄膜方块电阻随退火温度的变化情况,探索Ge2Sb2Te5薄膜的成长机理.实验结果表明,不同溅射功率下制备的薄膜经不同温度退火后方块电阻没有明显的区别,而随着溅射气压的上升,薄膜方块电阻随退火温度的增加,下降的速率增加,意味着由面心立方结构转变为六方结构所需的结晶温度降低.     

制备条件对Ge2Sb2Te5薄膜电学性能的影响

研究了磁控溅射制备Ge2Sb2Te5薄膜时,制备条件诸如功率、气压等对薄膜性能的影响.主要通过测量薄膜方块电阻随退火温度的变化情况,探索Ge2Sb2Te5薄膜的成长机理.实验结果表明,不同溅射功率下制备的薄膜经不同温度退火后方块电阻没有明显的区别,而随着溅射气压的上升,薄膜方块电阻随退火温度的增加,下降的速率增加,意味着由面心立方结构转变为六方结构所需的结晶温度降低.     

Thermoelectric Properties of Highly Deformed and Subsequently Annealed p-Type (Bi0.25Sb0.75)2Te3 Alloys

The effects of mechanical deformation and subsequent annealing on the thermoelectric properties and microstructure have been investigated for p-type (Bi_0.25Sb_0.75)₂Te₃ alloys prepared by melting followed by quenching. The mechanically deformed pellets were prepared by repetition of cold-pressing of quenched samples at room temperature. Cold-pressed pellets were then annealed at 300°C in vacuum, and the thermoelectric properties and microstructure were traced through the course of the heat treatment. For the heavily deformed samples, the Seebeck coefficient rapidly increased at the very early stage of annealing and did not change as the annealing time increased, due to recrystallization of a new δ-phase which equilibrated at the annealing temperature of 300°C (δ₃₀₀-phase). At the initial stage of annealing (recovery stage), the electrical resistivity sharply increased, probably due to the interaction of antistructural defects with vacancies produced during the cold-pressing treatment. However, for the lightly deformed samples, recrystallization occurred only at some portion of the grain boundaries, and the newly generated δ₃₀₀-phase slowly replaced the original, as-solidified δ_ingot-phase.     

Tunable Volatility of Ge2Sb2Te5 in Integrated Photonics

The operation of a single class of optical materials in both a volatile and nonvolatile manner is becoming increasingly important in many applications. This is particularly true in the newly emerging field of photonic neuromorphic computing, where it is desirable to have both volatile (short‐term transient) and nonvolatile (long‐term static) memory operation, for instance, to mimic the behavior of biological neurons and synapses. The search for such materials thus far have focused on phase change materials where typically two different types are required for the two different operational regimes. In this paper, a tunable volatile/nonvolatile response is demonstrated in a photonic phase‐change memory cell based on the commonly employed nonvolatile material Ge₂Sb₂Te₅ (GST). A time‐dependent, multiphysics simulation framework is developed to corroborate the experimental results, allowing us to spatially resolve the recrystallization dynamics within the memory cell. It is then demonstrated that this unique approach to photonic memory enables both data storage with tunable volatility and detection of coincident events between two pulse trains on an integrated chip. Finally, improved efficiency and all‐optical routing with controlled volatility are demonstrated in a ring resonator. These crucial results show that volatility is intrinsically tunable in normally nonvolatile GST which can be used in both regimes interchangeably.     

相变材料Ge2Sb2Te5的性质及其面向新型数据存储的应用

信息时代产生的海量数据驱动着计算机存储架构的革新,高性能的非易失性存储器和存算一体的神经形态计算成为存储体系的发展方向。首先,介绍了相变材料Ge2Sb2Te5的阻变性质的机理与应用,详细阐述了相变存储器的发展以及神经形态计算的实现。然后,讨论了基于Ge2Sb2Te5铁电性质的存储器、基于Ge2Sb2Te5介电性质的光子存储单元和基于Ge2Sb2Te5应变作用的高迁移率晶体管。最后,讨论了Ge2Sb2Te5和n型硅等材料的异质结结构在器件中的应用。基于Ge2Sb2Te5材料多种特性的新型存储器件必将在未来存算一体的数据处理中扮演重要的角色。     

激光致晶态Ge2Sb2Te5相变介质的光学常数

利用椭偏仪和光谱仪研究了结晶程度对Ge2Sb2Te5相变薄膜光学常数的影响.当初始化仪转速固定时,随激光功率的增加,折射率基本随之减小,消光系数逐渐增大,透过率逐渐减小;当激光功率固定时,随转速的增大,折射率也随之增大,消光系数随之减小,透过率逐渐增加.非晶态与晶态间的变换、薄膜微结构的变化(包括原子间键合状态的变化)以及薄膜内残余应力是影响Ge2Sb2Te5相变薄膜复数折射率的主要原因.测量了CD-RW(可擦重写光盘)中Ge2Sb2Te5薄膜非晶态和晶态的反射率.