锗纳米线的性能与应用

重点分析讨论了锗纳米线在电学、光学、光电导等特性及其在场效应晶体管制造方面的研究应用现状与最新进展。综合分析表明,未经处理的锗纳米线表面存在一层氧化物及缺陷,与电极连接时欧姆接触性能较差,在制备锗纳米线器件以前必须对锗纳米线表面进行钝化以便沉积电极;对锗纳米线进行掺杂可以改善Ge纳米线的性能,制造出实用Ge纳米线器件。指出在一根纳米线上生长硅/锗半导体纳米线形成硅/锗半导体界面,直接用单根纳米线制造具有完整功能的电子器件是将来重要的研究方向。     

硅基Ⅲ-Ⅴ族纳米线及其若干半导体器件

综述了硅基Ⅲ-Ⅴ族纳米线与异质结制备技术的研究进展.针对基于Ⅲ-Ⅴ族纳米线的半导体器件,重点介绍了硅基Ⅲ-Ⅴ族纳米线场效应晶体管的研究现状,详细介绍了硅基Ⅲ-Ⅴ族纳米线场效应晶体管和隧穿场效应晶体管的制备流程、工艺技术和器件的电学性能,并对影响器件电学性能的因素进行了分析.概括介绍了硅基Ⅲ-Ⅴ族纳米线激光器和硅基Ⅲ-Ⅴ族纳米线太阳电池的研究成果,基于硅衬底的Ⅲ-Ⅴ族纳米线太阳电池为低成本、高效能的太阳电池领域开辟了新途径.研究结果表明,采用硅基Ⅲ-Ⅴ族纳米线制备的场效应晶体管、激光器及太阳电池等半导体器件相对于Si,Ge等传统半导体材料制备的器件有着巨大的优势,在未来集成电路技术中具有越来越大的影响力.     

硅纳米线用于纳米器件前的准备工序

硅纳米线是一种新型半导体光电材料,具有量子限制效应并且能与目前的硅芯片相兼容,是一种很有前途的适用于纳米器件的材料,未经处理的硅纳米线存在大量的晶体缺陷以及表面氧化物保护层,直接将这样的硅纳米线应用于纳米器件中时,表面氧化层的保护作用使硅纳米线在电子器件中应用时不能有效地实现欧姆接触,因此对硅纳米线使用前的前期处理是非常必要的。本文主要针对硅纳米线应用于电子器件的准备工序包括为制备完整硅纳米线晶体结构而进行的减少缺陷处理、避免硅纳米线团聚而进行的分散处理,以及使硅纳米线具有有效欧姆接触而进行的表面金属离子处理等作系统的阐述。     

砷化镓半导体器件

一、引言锗、硅元素半导体在器件制造中已得到了很广泛的应用,在制造高频、大功率、高速开关晶体管方面也取得了非常可观的进展.为进一步改进晶体管的频率、功率、开关速度、使用温度等性能,以及扩展半导体器件的种类和应用,国外对新型半导体材料及其器件的探索相当重视.特别值得提出的是Ⅲ-V族化合物半导体及其器件.1952年Welker就已开始了Ⅲ-V族化合物半导体的研究,他指出这种化合物半导体有类似于锗、硅等Ⅳ族元素半导体的特性.十余年来,国外对这种半导体进行了许多研究工作,利用这种     

前言

<正>一代材料催生一代器件,引领一代产业。以硅、锗和砷化镓等半导体材料为代表的光电器件在过去几十年里对社会发展产生了深远影响,广泛地应用于集成电路、光电子与微电子等领域,形成了规模庞大的半导体产业集群。然而,这些光电器件的部分关键性能仍受限于材料的本征禁带宽度,更大的禁带宽度成了材料迭代的诉求。因此,发展宽禁带半导体材料成为突破硅、锗和传统Ⅲ-Ⅴ族化合物半导体器件瓶颈的关键,并与硅集成电路进行异质集成,拓展更为广泛的应用空间。硅、锗和传统的Ⅲ-Ⅴ族化合物半导体的高速发展得益于高质量单晶同质衬底材料,极低的缺陷密度保证了半导体器件的优异性能。     

半导体超晶格物理与器件（20）

在半导体超晶格物理与器件的研究中,锗硅超晶格、异质结、量子阱材料与器件的研究占据着十分重要的地位.这是因为,以Si_(1-x)Ge_x/Si和Ge/Si为主的硅基低维材料具有许多显著不同于体单晶硅,而且相异于Ⅲ-V族超晶格的优异性质,如可生长大直径尺寸单晶,机械强度高、导热性能好、制备工艺成熟、价格低廉,SiGe合金中Ge的组分可调,可与现代微电子技术相兼容,布里渊区的折叠效应可使Si由间接带隙变为直接带隙等,因此在微米波段,毫米波段,超高速ECL电路,红外焦平面阵列等高速电子器件及其集成光电子器件中有着潜在的应用.     

IBM公司宣布开关速度最快的锗硅晶体管

IBM公司近日宣布，采用一种新版本的高速锗硅工艺处理技术，已经试制成功世界上开关速度最快的锗硅晶体管。IBM公司称已经研制出的锗硅晶体管，其开关频率(Transit Frequency,简称Ft)可高达350GHz。这种晶体管据说比目前的器件快300%，比以前曾报道过的集成电路芯片快65%。根据该公司提供的材料，这种晶体管的性能优于用其他化合物半导体工艺(如砷化镓(GaAs)和磷化铟(InP)工艺)制造的器件。IBM公司宣称新的以锗硅工艺为基础的晶体管已经演示了其高速开关性能，但此技术目前仍处于研究开发阶段。该公司期望这种晶体管制造技术将会在2…     

硅基锗PIN红外探测器的数值模拟研究

本文基于漂移扩散模型,对硅基锗PIN红外探测器的电流特性随应变、Ge吸收层厚度、吸收层掺杂浓度的变化进行了数值模拟,并给出了一种器件优化设计方案.研究结果表明,当Ge应变从0增加到0.3%时,器件的暗电流增大了约50%;当Ge吸收层厚度从1μm增加到4μm时,器件的暗电流降低了近80%,量子效率增大了近1倍;当吸收层的掺杂浓度由1×1014cm-3增大2个量级时,器件的光电流降低了近60%.综合考虑吸收层厚度对器件量子效率和暗电流的影响以及吸收层掺杂浓度对光电流的影响,对硅基锗PIN红外探测器的外延锗吸收层进行了设计:外延生长厚度为4μm,掺杂浓度为1×1014cm-3,以期能为提高器件性能和制备实际器件提供良好的依据.     

砷化镓微波器件发展动态

在半导体器件的发展中,最初所用的材料主要是元素半导体锗。在1960年后,元素半导体硅的材料和器件工艺迅速发展起来,很快在半导体器件研制中占主要地位。目前也还在继续发展。但是,十多年来,化合物半导体的发展是很值得重视的。特别是Ⅲ—Ⅴ族化合物半导体材料中的砷化镓已在器件研制中取得了一定成果。砷化镓由于电子迁移率高、禁带宽等优点适于制造高频、大功率和高温器件。在一些器件中采用砷化镓材料后,获得了比同类锗、硅器件更高的性能。而且由于砷化镓特殊的能带结构,又发展了     

锗器件的表面机理和有效钝化途径——766专用硅脂的可靠性分析

锗晶体管的各种参数性能,严重地受到半导体表面状态的影响,而环境气氛的变化能改变半导体表面的性质,它是引起锗器件性能不稳定的主要根源。目前,对提高稳定性和可靠性仍然是生产单位和使用单位所急需解决的问题。 1972年10月四机部召开的半导体器件专业会议,不少锗器件生产单位反映,由于没有半导体器件专用的涂料和填料,给器件带来很大的影响,由于通常使用的涂料和填料不纯,优质的管芯在加涂料后性能变差,在装填充料封帽后,参数还会继续变坏,甚至使合格器件经过一段时间后变为废品。 福州无线电三厂顶住了“四人帮”的干扰破坏,在党支部的领导下,组织了“三结合”专用硅脂研制小组,福州大学教师具体指导,于1976年6月研制成功锗器件专用填料——766硅脂。并于1977年4月由四机部定为全国推广项目。     

氧化铝模板法制备Ge纳米线

采用氧化铝模板法结合具有高真空背景的低压化学气相沉积技术制备出 Ge纳米线 .在氧化铝模板的背面喷金作为催化剂 ,合成了 Ge纳米线 .采用原子力显微镜、X射线衍射、透射电镜、能量散射谱等手段对 Ge纳米线进行了分析 .Ge纳米线的直径约为 30 nm,长度超过 6 0 0 nm.对 Ge纳米线的生长机理进行了探讨 .     

Electrochemical Properties of Si‐Ge Heterostructures as an Anode Material for Lithium Ion Batteries

Si‐Ge composites have recently been explored as an anode material for lithium‐ion batteries due to their stable cycle performance and excellent rate capability. Although previous reports show the benefits of Si‐Ge composites on electrochemical performance, the specific mechanism and structural effects have been overlooked. Here, the structural effect of Si‐Ge heterogeneous nanostructures on both mechanics and kinetics is systematically studied through theoretical analysis and detailed experimental results. Si‐Ge and Ge‐Si core–shell nanowires are employed for this study. The Si‐Ge core–shell nanowires show a much improved electrochemical performance, especially cycle performance and rate capability, when compared to those of the Ge‐Si core–shell nanowires electrode. On the basis of the detailed experimental results and associated theoretical analysis, its is demonstrated that the strain distribution and Li diffusivity and/or diffusion path are significantly affected by the Si‐Ge heterostructure, which induce different mechanics and kinetics associated with lithium.     

Controllable growth of GeSi nanostructures by molecular beam epitaxy

We present an overview on the recent progress achieved on the controllable growth of diverse GeSi alloy nanostructures by molecular beam epitaxy. Prevailing theories for controlled growth of Ge nanostructures on patterned as well as inclined Si surfaces are outlined firstly, followed by reviews on the preferential growth of Ge nanoislands on patterned Si substrates, Ge nanowires and high density nanoislands grown on inclined Si surfaces, and the readily tunable Ge nanostructures on Si nanopillars. Ge nanostructures with controlled geometries, spatial distributions and densities, including two-dimensional ordered nanoislands, three-dimensional ordered quantum dot crystals, ordered nanorings, coupled quantum dot molecules, ordered nanowires and nanopillar alloys, are discussed in detail. A single Ge quantum dot-photonic crystal microcavity coupled optical emission device demonstration fabricated by using the preferentially grown Ge nanoisland technique is also introduced. Finally, we summarize the current technology status with a look at the future development trends and application challenges for controllable growth of Ge nanostructures.     

Crystallinity‐Controlled Germanium Nanowire Arrays: Potential Field Emitters

We report a simple method, oblique angle deposition, to directly synthesize aligned Ge nanowire arrays on a Si substrate. This process is accomplished by tilting the Si substrate and adjusting the incident angle of the evaporated Ge vapor flux with respect to the substrate normal to 87°. The resultant crystallinity of the Ge nanostructures can be tuned to either amorphous or poly‐ and single‐crystalline, depending on the substrate temperature and evaporation rate. The effects of thermal treatment on the morphology and structure of the Ge nanowires are discussed in detail. The field‐emission measurements show that increasing the annealing temperatures to about 550 °C results in a gradual increase in the maximum current density and a decrease in the turn‐on voltage, because of the decreased wire density originating from melting of the Ge nanowires. The field‐enhancement factor analysis shows there is an optimum range for Ge wire density and aspect ratio to obtain good emission performance. Ge nanowire arrays might find potential application in the field emitters of the future.     

Doping top-down e-beam fabricated germanium nanowires using molecular monolayers

This paper describes molecular layer doping of Ge nanowires. Molecules containing dopant atoms are chemically bound to a germanium surface. Subsequent annealing enables the dopant atoms from the surface bound molecules to diffuse into the underlying substrate. Electrical and material characterization was carried out, including an assessment of the Ge surface, carrier concentrations and crystal quality. Significantly, the intrinsic resistance of Ge nanowires with widths down to 30 nm, doped using MLD, was found to decrease by several orders of magnitude.     

Germanium-Rich SiGe Nanowires Formed Through Oxidation of Patterned SiGe FINs on Insulator

In this study, the authors report on the fabrication of Ge-rich SiGe nanowires (SGNWs) by oxidation of SiGe fins on insulator. Nanowires of different shapes and size are obtained by varying the initial fin shape, Ge content, oxidation process temperature, and oxidation time. Transmission electron microscopy observations revealed nanowires with rectangular, square, elliptical, circular, octagonal, and hexagonal cross-sections, with different Ge content. The elliptical, octagonal, and hexagonal facets are unique shapes formed with low-index faces belonging to (110) groups. These possess very high Ge content up to 95%, and were obtained in the samples oxidized from 850°C to 875°C. In␣addition, the in-plane strain in the fabricated SGNWs is evaluated using micro-Raman spectroscopy. The possible mechanism behind the formation and transformation of different nanowire shapes is discussed.     

Locally Welded Silver Nano‐Network Transparent Electrodes with High Operational Stability by a Simple Alcohol‐Based Chemical Approach

As an indispensable aspect of emerging flexible optoelectronics, flexible transparent electrodes, especially those comprised of metal nanowires, have attracted great attentions recently. Welding the nanowire junctions is an effective strategy for reducing the sheet resistance and improving the operational stability of flexible nanowire electrode in practical applications. Herein, a simple alcohol‐based solution approach is proposed to weld crossed silver nanowires by chemically growing silver “solder” at the junctions of the nanowires, forming transparent silver nano‐network electrodes with improved electrical conductivity and operational stability. Remarkably, silver nano‐networks can be rapidly formed by this simple approach under ambient condition and room temperature, requiring no assistance from heat, light, electrical current, or mechanical pressure. Furthermore, our results show that the nano‐network electrode formed from large diameter nanowires offers a better operational stability, whose trend is opposite to that of the untreated electrodes. To demonstrate the potential application of the highly stable silver nano‐network from large diameter nanowires, organic solar cells fabricated on the nano‐network electrode incorporated with silicon dioxide nanoparticles achieve comparable performance to the ITO control device. Consequently, strategy demonstrated in this work can contribute to low‐cost and highly stable transparent electrodes in emerging flexible optoelectronics.     

零维和一维半导体纳米结构

介绍了几种零维和一维无机半导体纳米结构的制备及其应用。其中,零维无机半导体纳米结构以Si,Ge量子点为代表,一维无机半导体纳米结构以碳纳米管、硅纳米线、氧化锌纳米线和氮化镓纳米结构为代表,介绍了它们的制备和应用研究动态;最后分析了纳米技术的研究和抢占技术制高点的重要性。     

Inkjet-printed Ag grid combined with Ag nanowires to form a transparent hybrid electrode for organic electronics

Networks of silver nanowires (AgNW) have been shown to facilitate high transparency, high conductivity, and good mechanical stability. However,the loose characteristic and local insulation problems due to gaps between the nanowires limit their application as electrodes. This study investigates an inkjet-printed Ag grid combined with AgNW to form a transparent hybrid electrode. The printed Ag grid on AgNW film connects the gaps between the Ag nanowires to increase the overall electric conductivity. The printed Ag-grid/AgNW hybrid electrodes have low resistivity (22.5 Ω/□) while maintaining a high transmittance (87.5%). These values are similar to standard indium tin oxide (ITO) on glass which has resistivity of 20Ω/□ and transmittance of 89% at 550 nm. In addition, these hybrid electrodes are also very flexible when fabricated on a photopolymer substrate. A spin-coating process combined with a peel-off process enable the fabrication of flexible ultra-smooth Ag-grid/AgNW electrodes. We tested the transparent and flexible electrode as the anode of a flexible organic light emitting diode (F-OLED). The light emitting layer of the F-OLED is 35 nm thick tris-(8-hydroxyquinoline) aluminum doped with 0.5% 10-(2-benzothiazolyl)-2,3,6,7-tetrahydro-1,1,7,7-tetramethyl-1H,5H,11H-(1)-benzopyropyrano(6,7-8-I,j)quinolizin-11-one. The maximum brightness and current efficiency of the F-OLED are 10000 cd/m² and 12 cd/A, respectively, even when bent around a radius of 2 mm. The good performance of the device with Ag-grid/AgNW hybrid electrodes show that enhanced conductive inkjet-printed Ag nanoparticles combined with Ag nanowires can produce high quality electrodes for flexible organic optoelectronic devices.