光电子领域中的纳米半导体材料

近年来，纳米半导体材料特别是纳米硅在光电子领域中的研究已经越来越引起人们的注意，由于纳米半导体材料的量子限域效应，尺寸效应等影响使得它们在光电转移，电子器件等方面有着优异的性能，必将在未来的微电子以及纳米电子发展中发挥令人鼓舞的作用，详细介绍了纳米半导体材料在光电子领域中的发展历史，研究情况以及存在的问题等。     

硅纳米晶体的制备、性质及其在光电器件中的应用

硅纳米晶体作为最重要的元素半导体 硅的一种纳米形式，由于具有独特的光电特性和友好的环境相容性引起了研究者们的广泛关注。近年来，人们围绕着量子限域效应、表面效应和掺杂效应三个最重要的因素对硅纳米晶体的性质开展了研究，并通过三者对硅纳米晶体的电学和光学性能进行调控，使其满足面向印刷电子、硅基集成和生物兼容的高性能光电器件的应用。目前，基于硅纳米晶体的太阳能电池、发光二极管和光电探测器等重要光电器件已经被研制出来。综述了近年来国内外研究者们在硅纳米晶体的制备、性质研究及其在光电器件中的应用所取得的研究进展，并展望了硅纳米晶体在材料性能调控方面的发展前景。     

Au与p-CZT接触的界面势垒研究

用同步光电子能谱研究了NH4F/H2O2钝化p-CZT表面效应, 钝化处理晶体表面后,表面态能峰消失.用未钝化和钝化两种工艺方法来对比p-CZT晶体表面的钝化效果.同时用同步光电子能谱研究了Au与p-CZT接触的界面势垒.其中界面势垒可以由价带区域的新能级EV-C 和新能级与Fermi能级的差决定.未钝化和钝化的Au/p-CZT的界面势垒分别为(0.88±0.1)eV和(1.17±0.1)eV.     

近红外波段光子晶体的微细加工方法研究进展

光子晶体及其在光电子领域的应用是目前国际上的研究热点之一，是一种新型的光电子功能材料。在近红外光通讯领域中，光子晶体(对应允子晶体晶格常数为亚微米)有非常重要的应用，可以制作许多以前所不能制作的高性能光学器件。如何制备用于光通讯领域的光子晶体越来越引起广泛关注。本文综述了近红外波段光子晶体的微细加工制备方法的研究进展。     

GaN和AlxGa1—xN薄膜材料研究进展

ＧａＮ及ＡｌｘＧａ１－ｘＮ是发兰光的关键材料，是目前光电子材料中最引人注目，必须攻克的课题。本文综述了ＧａＮ及ＡｌｘＧａ１－ｘＮ材料的研究现状重点介绍了ＧａＮ及ＡｌｘＧａ１－ｘＮ材料近年来在性能评价，生长技术和应用开发方面的进展。     

纳米晶体材料的Hall—Petch关系

本文综述了纳米晶体材料力学性能如屈服应力，显微硬度的研究，尤其是偏离正常Ｈａｌｌ－Ｐｅｔｃｈ关系的现象及几种解释这种反常效应的模型，分析表明：纳米晶体材料的强度或硬度取决于材料的界面缺陷结构，界面过剩能与过剩体积。     

苏州工业园区打造纳米技术产业基地

苏州工业园区已经获批国家级纳米技术产业和创新基地，将重点发展纳米新材料、纳米光电子、纳米生物医药等新兴产业。     

纳米TiO2的性能、应用及制备方法

纳米TiO2具有独特的光催化性、优异的颜色效应以及紫外线屏蔽等功能，在光催化剂、化妆品、抗紫外线吸收剂、功能陶瓷、气敏传感器件等方面具有广阔的应用前景，国内外文献对纳米TiO2的性质、应用及其制备方法进行了大量的研究报道。本工作对有关纳米TiO2的性能、应用及制备方法研究进行了综述。     

乌克兰在荧光纳米材料研究方面取得新成果

正近年来,科学界兴起了对特殊性质纳米材料的研究,其中,荧光纳米晶体和纳米结构复合材料的研究从理论到实践都引起科学家的广泛兴趣。纳米粉末荧光和闪烁材料的应用使得其光学特性在宽范围内发生变化。乌克兰国家科学院闪烁材料研究所荧光及闪烁材料物理实验室开展了对荧光纳米晶体和纳米结构复合材料的研究,取得一系列科研成果。通过一系列实验,该实验室科学家首次发现二氧化铈纳米晶体的抗氧化性能可通过光谱学方法来控制,二氧化铈纳     

光折变晶体材料的研究进展

具有光折变效应的晶体称为光折变晶体材料,属于光子学材料。光子学材料是指大容量相干光通讯和高信息处理率的全光计算机,以及图象处理系统所需求的材料。目前由于光子学和光电子学两学科处于相互交叉共生的阶段,因而光子材料与光电子材料也是相互交叉的。光折变效应和各类光折变晶体材料是目前极为活跃的研究领域。光折变效应本来是非线性光学的一部分,但是近年来发现光折变晶体具有一系列独特的性质,     

Self-assembly of colloidal nanocrystals as route to novel classes of nanostructured materials

Colloidal crystallisation is the only way to obtain three-dimensional ordered materials in which semiconductor, metallic, and magnetic nanocrystals are in close contact. It is expected that the quantum mechanical and dipolar interactions between the nanocrystal units can lead to unseen physical phenomena and materials. Here we review the development of this new and exciting field. We first compare nanocrystal superlattices with regular atomic solids regarding their mechanical strength and opto-electronic properties. We describe how nanocrystal superlattices have been obtained from colloid suspensions in several ways. The thermodynamic driving force for colloidal crystallisation is discussed in terms of inter-particle interactions in a good solvent and entropy. We compare the binary superlattices that have been obtained by solvent evaporation with the predictions of the hard-sphere model and show that semiconductor nanocrystals in a good solvent can behave as hard spheres. Finally, we discuss the quantum mechanical and dipolar interactions in nanocrystal superlattices and review recent studies of the opto-electronic and magnetic properties of novel superlattice materials.     

Nanopatterned electrically conductive films of semiconductor nanocrystals

We present the first semiconductor nanocrystal films of nanoscale dimensions that are electrically conductive and crack-free. These films make it possible to study the electrical properties intrinsic to the nanocrystals unimpeded by defects such as cracking and clustering that typically exist in larger-scale films. We find that the electrical conductivity of the nanoscale films is 180 times higher than that of drop-cast, microscopic films made of the same type of nanocrystal. Our technique for forming the nanoscale films is based on electron-beam lithography and a lift-off process. The patterns have dimensions as small as 30 nm and are positioned on a surface with 30 nm precision. The method is flexible in the choice of nanocrystal core-shell materials and ligands. We demonstrate patterns with PbS, PbSe, and CdSe cores and Zn(0.5)Cd(0.5)Se-Zn(0.5)Cd(0.5)S core-shell nanocrystals with a variety of ligands. We achieve unprecedented versatility in integrating semiconductor nanocrystal films into device structures both for studying the intrinsic electrical properties of the nanocrystals and for nanoscale optoelectronic applications.     

3D Nanofabrication via Chemo‐Mechanical Transformation of Nanocrystal/Bulk Heterostructures

Planar nanocrystal/bulk heterostructures are transformed into 3D architectures by taking advantage of the different chemical and mechanical properties of nanocrystal and bulk thin films. Nanocrystal/bulk heterostructures are fabricated via bottom‐up assembly and top‐down fabrication. The nanocrystals are capped by long ligands introduced in their synthesis, and therefore their surfaces are chemically addressable, and their assemblies are mechanically “soft,” in contrast to the bulk films. Chemical modification of the nanocrystal surface, exchanging the long ligands for more compact chemistries, triggers large volume shrinkage of the nanocrystal layer and drives bending of the nanocrystal/bulk heterostructures. Exploiting the differential chemo‐mechanical properties of nanocrystal and bulk materials, the scalable fabrication of designed 3D, cell‐sized nanocrystal/bulk superstructures is demonstrated, which possess unique functions derived from nanocrystal building blocks.     

晶体生长用TiO2纳米晶的改良工艺研究

针对晶体生长的具体应用,分别以硫酸氧钛铵（ATS）和改良硫酸氧钛铵（M－ATS）为原料,采用高温焙烧法制备了TiO2纳米晶,用XRD分析了原料和纳米晶的物相,用SEM分析了纳米晶的形貌,结果表明虽然两种原料具有相似的物相结构,但所得纳米晶的性状不同,M－ATS焙烧所得纳米晶分散性更高,均匀性更好,此外,研究了焙烧温度,保温时间,急烧,缓烧等工艺条件对纳米晶形貌,物相的影响,并给出了批量制备TiO2纳米晶粉体的最佳工艺条件。     

A figure of merit for optimization of nanocrystal flash memory design

Nanocrystals can be used as storage media for carriers in flash memories. The performance of a nanocrystal flash memory depends critically on the choice of nanocrystal size and density as well as on the choice of tunnel dielectric properties. The performance of a nanocrystal memory device can be expressed in terms of write/erase speed, carrier retention time and cycling durability. We present a model that describes the charge/discharge dynamics of nanocrystal flash memories and calculate the effect of nanocrystal, gate, tunnel dielectric and substrate properties on device performance. The model assumes charge storage in quantized energy levels of nanocrystals. Effect of temperature is included implicitly in the model through perturbation of the substrate minority carrier concentration and Fermi level. Because a large number of variables affect these performance measures, in order to compare various designs, a figure of merit that measures the device performance in terms of design parameters is defined as a function of write/erase/discharge times which are calculated using the theoretical model. The effects of nanocrystal size and density, gate work function, substrate doping, control and tunnel dielectric properties and device geometry on the device performance are evaluated through the figure of merit. Experimental data showing agreement of the theoretical model with the measurement results are presented for devices that has PECVD grown germanium nanocrystals as the storage media.     

Influence of separation of Si nanocrystals embedded in a SiO2 matrix on electronic and optical properties

The influence of the nanocrystal separation of Si nanocrystals embedded in an amorphous SiO₂ matrix is investigated using ab initio density functional theory. We consider different structural models of Si nanocrystals embedded in a SiO₂ matrix with the same nominal nanocrystal diameter but different nanocrystal separations. We demonstrate that the nanocrystal distance influences electronic, optical and dielectric properties.     

Photoluminescence waveguiding in CdSe and CdTe QDs-PMMA nanocomposite films

In this paper, active planar waveguides based on the incorporation of CdSe and CdTe nanocrystal quantum dots in a polymer matrix are demonstrated. In the case of doping the polymer with both types of quantum dots, the nanocomposite film guides both emitted colors, green (550?nm, CdTe) and orange (600?nm, CdSe). The optical pumping laser can be coupled not only with a standard end-fire coupling system, but also directing the beam to the surface of the sample, indicating a good absorption cross-section and waveguide properties. To achieve these results, a study of the nanocomposite optical properties as a function of the nanocrystal concentration is presented and the optimum conditions are found for waveguiding.     

Synthesis, structure and properties of superhard nanostructured films deposited by the C60 ion beam

In this work, we present results on study of DLC, nanocomposite and nanocrystal nanographite films synthesized utilizing mass-separated beam of C60-ions with energy in range from 2 to 6 keV (energy dispersions approximately 1 keV) and at Ts in the range of RT - 873 K. The dependence of the structure, mechanical and electrical properties from the ion energy and substrate temperature was revealed. We demonstrate a possibility to control the orientation of the base planes in the nanographite grains during the film growth. The dependence of mechanical properties of the films from the orientation of the base planes was defined. It is discussed a mechanisms of oriented growth for nanocrystal graphite. Possible applications of the textured nanocomposite and nanographite films are nanodevices, thin-filmed lithium batteries and field-emitter arrays.     

经验电子理论在纳米晶软磁材料中的应用及展望

概述了固体与分子经验电子理论（简称EET理论）在一般材料和纳米晶软磁材料中的应用现状,提出了EET理论在纳米晶软磁材料应用中尚存在的问题,并给出了一些解决方案,最后展望了EET理论在纳米晶软磁材料中的应用前景。     

Non-vacuum and PLD growth of next generation TCO materials

Transparent conducting oxides represent a key component in a number of important opto-electronic technologies. The demand for improved materials is increasing. It is increasingly important to develop improved materials and process techniques. We report on the PLD growth of both Mo doped In-O, an n-type material with enhanced mobilities, and p-type Ca-CuInO₂ films with improved conductivity. In both cases, very high quality films have been obtained with improved opto-electronic properties. We also report on a solution based route to p-type Cu₂SrO₂ which has produced phase pure films.