相变随机存储器材料与结构设计最新进展

介绍了相变随机存储器(PCRAM)的研究现状,包括新型相变材料、热阻层材料和器件结构等.分析了GeSb和SiSb等相变材料具有组分简单、数据保持力好、优良的存储性能等特点,介绍了PCRAM这一新型半导体存储器的基本原理、特点以及国内外有关相变材料、过渡层材料和器件结构设计等方面的研究进展,最后提出了我国发展PCRAM的几点思考.     

相变异质结(PCH)存储材料相变行为的原位观测

相变存储器(PCM)具有速度快、寿命长等一系列优点.传统的相变存储器在相变过程中会产生蘑菇状的相变层,导致沿电流方向的元素迁移,使器件在多次循环之后失效.相变异质结(phase-change heterostructure,PCH)存储材料通过在相变材料Sb2Te3(ST)中嵌入约束层TiTe2(TT),能够有效降低其...     

相变材料及其在热红外伪装领域的应用研究

综述了各种相变材料(PCM)的性能特点及研究现状,研究分析了相变材料在军事热红外伪装领域中的应用机理及其在伪装纺织品和假目标中的应用,最后探讨了将相变材料应用于热红外伪装需要解决的问题.     

嵌入式相变存储器的技术特点和研究现状

从2001年Intel在IEDM发表第一篇相变存储器的论文以来,相变存储器的发展十分迅猛.相变存储器由于具有非易失性、循环寿命长、元件尺寸小、功耗低、可多级存储、高速读取、抗辐射、耐高低温、抗振动、抗电子干扰和制造工艺简单等优点,被认为最有可能取代目前的FLASH和DRAM而成为未来半导体存储器主流产品.文中系统地介绍了嵌入式相变存储器的存储机理及其主要工作特点,从相变材料,器件结构,存储阵列等方面分析国内外研究现状,并讨论了器件失效与可靠性问题.     

Pb1-xGexTe薄膜在铁电相变点的折射率异常

对在80～300K温度范围测量的Pb1-xGexTe(x=0.06)薄膜透射谱采用Lorentz谐振子模型进行拟合得到折射率.研究发现:在其铁电相变温度150K折射率出现极大值.折射率的极大值是晶体电容率异常的标志,而晶体电容率异常正是晶体相变具有铁电性的反映,因此同电阻和比热一样,折射率在铁电相变点也出现了异常.在所研究的光谱及温度范围,折射率与材料的禁带宽度不遵循Moss定则等经验公式.     

Pb1-xGexTe薄膜在铁电相变点的折射率异常

对在80～300K温度范围测量的Pb1-xGexTe(x=0.06)薄膜透射谱采用Lorentz谐振子模型进行拟合得到折射率.研究发现:在其铁电相变温度150K折射率出现极大值.折射率的极大值是晶体电容率异常的标志,而晶体电容率异常正是晶体相变具有铁电性的反映,因此同电阻和比热一样,折射率在铁电相变点也出现了异常.在所研究的光谱及温度范围,折射率与材料的禁带宽度不遵循Moss定则等经验公式.     

锆钛酸钡掺杂改性研究进展

综述了锆钛酸钡(BaZrxTi1–xO3,简称BZT)材料的掺杂种类以及掺杂对晶粒尺寸、相变温度、介电非线性和介电弛豫的影响等方面的最新研究进展,提出了研究中在掺杂与结构等方面需要解决的一些问题。     

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。     

二氧化钒在红外自适应隐身技术中的应用

二氧化钒(VO2)是一种热致可逆相变氧化物,在约68℃时发生由半导体态向金属态的一级位移型相变,同时伴随着显著的电学、磁学、光学特性的变化,且相变温度可通过掺杂调节。制备了二氧化钒粉体和薄膜材料,分别研究了两种材料的热致红外发射率变化特性;采用热像仪拍摄了二氧化钒涂层和薄膜不同温度的红外热图,探讨了其在隐身技术中的应用。结果表明:二氧化钒涂层和薄膜在相变前后具有主动控制自身辐射强度的特性,在红外自适应隐身技术中具有一定的应用前景。     

低温铁电相变

本文阐述了低温铁电相变,研究了量子效应时铁电相变的影响和抑制。提出了具有此种特征的材料可应用之处。     

Spintronics

Investigations of the dynamics of spin-polarized electronic current through and near materials with spin-dependent electronic structures have created a rich new field dubbed "spintronics". The implications of spintronics research extend deep into the realm of fundamental material properties, yet spintronics applications have also revolutionized the magnetic-storage industry by providing efficient room-temperature magnetic sensors. Control of nonequilibrium spin-polarized populations of electrons through and near magnets has led to the dominance of linear (resistive) spintronic devices for magnetic readout in commercial magnetic storage. Rapid progress in understanding the fundamental physics of nonlinear spin-polarized electronic transport in metals and semiconductors suggests new applications for spintronic devices in fast nonvolatile memory as well as logic devices, with or without magnetic materials or magnetic fields. Ongoing study of the interaction between such spintronic elements and optical fields, particularly in semiconductors, promises the future development of optical spintronic devices     

Phase change materials and their application to random access memory technology

Phase change materials can exist in two different phases, the amorphous and the crystalline phase, which exhibit distinctly different physical properties. It is possible to repeatedly switch the state of these materials, from the amorphous phase to the crystalline phase by heating the material above its crystallization temperature, and from the crystalline to the amorphous phase by melt-quenching. Phase change materials have been utilized very successfully in all modern optical re-writable storage media such as CDs, DVDs and Blu-ray disks. Recently, they have also been applied to solid-state memory devices where their large difference in electrical resistivity is used to store information. This paper reviews the unique properties of phase change materials in particular as they are important for their application to these devices.     

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.     

A guideline for designing chalcogenide-based glasses for thresholdswitching characteristics

Chalcogenide-based switching materials have potential applications in power control and information storage. In this work, an approach has been suggested to design chalcogenide-based amorphous materials for threshold or memory switching characteristics. Using this guideline, glasses have been formed in a new chalcogenide Al-Ge-As-Te system. All the samples studied have been found to exhibit threshold switching characteristics, which proves the validity of the suggested guideline     

An overview of optical data storage technology

Optical techniques for data storage have advanced rapidly during the last decade. Optical data storage presents many unique advantages, notably the high storage density and low access time, not attainable by conventional recording techniques. The special features of optical recording, the proposed materials and techniques, the components for optical storage as well as some representative optical bit-by-bit and holographic recording systems are reviewed. It is noted that in spite of the lack of widespread commercial success of the optical recording at the present, some unique devices have been successfully demonstrated. The knowledge accumulated in the development of optical data storage should be useful for many recent Applications such as video recording. It is expected that when the conventional magnetic memory technology reaches its limit, optical storage technology should be a competitive contender for the next generation data storage.     

Photorefractive optics in three-dimensional digital memory

To exceed the capacity limitation of the surface-recording method of current optical data storage, the third dimension is introduced with photorefractive materials. Photorefractive materials are suitable for three-dimensional data storage in conjunction with nonlinear optical systems such as the two-photon absorption process of the material for recording and the confocal laser-scanning system for reading. I will describe the systems and the materials for three-dimensional digital memory with the experimental results for read-only memory with photopolymer, erasable memory with a lithium niobate crystal and rewritable memory with photochromic organic materials. The comparison between photorefractive digital three-dimensional memory with conventional holographic three-dimensional memory and near-field memory is also discussed in terms of dynamic range, noise, recording density, and accessibility     

光致二阶非线性玻璃材料的研究进展

光致二阶非线性功能玻璃材料是近年来最新出现的一类非线性光学材料，并有可能发展成为新的高密度光存储介质．本文综述了光致二阶非线性功能玻璃材料的研究进展，包括光学玻璃纤维及玻璃体材料的光致二阶非线性效应的实验研究、理论模型及其光存储应用．     

Send a hologram [photorefractive materials]

As computers and the Internet become faster and faster, more and more information is transmitted, received, processed, and stored everyday. The demand for high-speed, large-capacity information systems is pushing scientists and engineers to explore all possible approaches, including electrical and optical means. Photorefractive materials and devices are becoming viable alternatives for information systems. Photorefractive materials, including traditional electrooptic photorefractive crystals as well as photopolymers and photosensitive glasses, have demonstrated their potential in information systems. In this article we describe several applications of various photorefractive materials in information storage, processing, and communication systems. Specifically, we briefly discuss the applications of the traditional electrooptic photorefractive crystals and photopolymers in volume holographic data storage (VHDS) and information processing. Then, we discuss our recent works on the applications of photopolymers, holographic polymer dispersed liquid crystals (H-PDLC), and photosensitive glasses in photonic devices for optical fiber communications.     

Recent Advances in 2D MXenes for Photodetection

A new class of 2D transition metal carbides, carbonitrides and nitrides, termed MXenes, has emerged as a new candidate for many applications in electronics, optoelectronics, and energy storage. Since their first discovery in 2011, MXenes have gathered increasingly more interest owing to their unique physical, chemical, and mechanical properties that can be tuned by different surface terminations and transition metals. In particular, the intriguing optical and electrical properties, including transparency, saturable absorption, and high conductivity, grant MXenes various roles in photodetectors, such as transparent electrodes, Schottky contacts, photoabsorbers, and plasmonic materials. Given the solution‐processability, MXenes also hold great potential for large‐scale synthesis, and thus are favored for a number of electronic and photonic device applications. In this review, recent advances in photodetectors based on 2D MXenes are summarized. Despite the fact that such applications have only recently been explored compared with other 2D materials, MXenes have shown promise in low‐cost and high‐performance photodetection.     

Storage system support for continuous-media applications. Part 1. Requirements and single-disk issues

A multimedia storage system plays a vital role for the performance and scalability of multimedia servers. To handle the server load imposed by increased user access to on-demand multimedia streaming applications, new storage system solutions are needed. Multimedia storage systems store and retrieve data from storage devices and manage related issues including data placement, scheduling, file management, continuous data delivery, memory buffering, and prefetching. For high-data-rate multimedia systems, storage systems have long been viewed as a primary bottleneck for two reasons. First, multimedia applications have a much higher storage system load than previous applications. Second, storage devices have become only marginally faster compared to increased processor and network performance. This increasing speed mismatch has fueled a search for new storage structures and file system storage and retrieval mechanisms