PLD脉冲激光沉积简介电子教案.docx
《PLD脉冲激光沉积简介电子教案.docx》由会员分享,可在线阅读,更多相关《PLD脉冲激光沉积简介电子教案.docx(12页珍藏版)》请在咨信网上搜索。
1、PLD脉冲激光沉积简介精品文档英文原文:CHAPTER 1Pulsed Laser Deposition of Complex Materials: Progress Towards ApplicationsDAVID P. NORTONUniversity of Florida, Department of Materials Science and Engineering, Gainesville, Florida1.1 INTRODUCTIONIn experimental science, it is a rare thing for a newly discovered (or re
2、discovered) synthesis technique to immediately deliver both enhanced performance and simplicity in use in a field of accelerating interest. Nevertheless, such was the case with the rediscovery of pulsed laser deposition (PLD) in the late 1980s. The use of a pulsed laser as a directed energy source f
3、or evaporative film growth has been explored since the discovery of lasers Hass and Ramsey, 1969; Smith and Turner, 1965. Initial activities were limited in scope and involved both continuous-wave (cw) and pulsed lasers. The first experiments in pulsed laser deposition were carried out in the 1960s;
4、 limited efforts continued into the 1970s and 1980s. Then, in the late 1980s, pulsed laser deposition was popularized as a fast and reproducible oxide film growth technique through its success in growing in situ epitaxial high-temperature superconducting films Inam et al., 1988. The challenges for i
5、n situ growth of high-temperature superconducting oxide thin films were obvious. The compounds required multiple cations with diverse evaporative properties that had to be delivered in the correct stoichiometry in order to realize a superconducting film. Simultaneously, the material was an oxide, re
6、quiring an oxidizing ambient during growth. Pulsed laser deposition had several characteristics that made it remarkably competitive in the complex oxide thin-film research arena as compared to other film growth techniques. These principle attractive features were stoichiometric transfer, excited oxi
7、dizing species, and simplicity in initial setup and in the investigation of arbitratry oxide compounds. One could rapidly investigate thin-film deposition of nearly any oxide compound regardless of the complexity of the crystal chemistry. Significant development of pulsed laser deposition has contin
8、ued and over the past 15 years, PLD has evolved from an academic curiousity into a broadly applicable technique for thin-film deposition research Saenger, 1993; Kaczmarek, 1997; Willmott and Huber, 2000; Dubowski, 1988; Dieleman et al., 1992. Today, PLD is used in the deposition of insulators, semic
9、onductors, metals, polymers, and even biological materials. Few material synthesis techniques have enjoyed such rapid and widespread penetration into research and application venues.Pulsed Laser Deposition of Thin Films: Applications-Led Growth of Functional MaterialsEdited by Robert Eason Copyright
10、 # 2007 John Wiley & Sons, Inc.3收集于网络,如有侵权请联系管理员删除 1.2 WHAT IS PLD?The applicability and acceptance of pulsed laser deposition in thin-film research rests largely in its simplicity in implementation. Pulsed laser deposition is a physical vapor deposition process, carried out in a vacuum system,that
11、shares some process characteristics common with molecular beam epitaxy and some with sputter deposition. In PLD, shown schematically in Figure 1.1, a pulsed laser is focused onto a target of the material to be deposited. For sufficiently high laser energy density, each laser pulse vaporizes or ablat
12、es a small amount of the material creating a plasma plume. The ablated material is ejected from the target in a highly forward-directed plume. The ablation plume provides the material flux for film growth. For multicomponent inorganics, PLD has proven remarkably effective at yielding epitaxial films
13、. In this case, ablation conditions are chosen such that the ablation plume consists primarily of atomic, diatomic, and other low-mass species. This is typically achieved by selecting an ultraviolet (UV) laser wavelength and nanosecond pulse width that is strongly absorbed by a small volume of the t
14、arget material. Laser absorption by the ejected material creates a plasma. For the deposition of macromolecular organic materials, conditions can be chosen whereby absorption is over a larger volume with little laser absorption in the plume. This permits a large fraction of the molecular material to
15、 be ablated intact. For polymeric materials, transfer of intact polymer chains has been demonstrated. For even softer materials in which the direct absorption by the laser would be destructive to molecular functionality, the formation of composite ablation targets consisting of the soft component em
16、bedded in an optically absorbing matrix has been investigated (see, e.g., Chapter 3).Several features make PLD particularly attractive for complex material film growth. These include stoichiometric transfer of material from the target, generation of energetic species, hyperthermal reaction between t
17、he ablated cations and the background gas in the ablation plasma, and compatibility with background pressures ranging from ultrahigh vacuum (UHV) to 1 Torr. Multication films can be deposited with PLD using single, stoichiometric targets of the material of interest, or with multiple targets for each
18、 element. With PLD, the thickness distribution from aFigure 1.1 Schematic of the PLD process.stationary plume is quite nonuniform due to the highly forward-directed nature of the ablation plume. To first order, the distribution of material deposited from the ablation plume is symmetric with respect
19、to the target surface normal and can be described in terms of a cosny distribution, where n can vary from 430. However, raster scanning of the ablation beam over the target and/or rotating the substrate can produce uniform film coverage over large areas, and this topic is covered in Chapter 9.One of
20、 the most important and enabling characteristics in PLD is the ability to realize stoichiometric transfer of ablated material from multication targets for many materials. This arises from the nonequilibrium nature of the ablation process itself due to absorption of high laser energy density by a sma
21、ll volume of material. For low laser fluence and/or low absorption at the laser wavelength, the laser pulse would simply heat the target, with ejected flux due to thermal evaporation of target species. In this case, the evaporative flux from a multicomponent target would be determined by the vapor p
22、ressures of the constituents. As the laser fluence is increased, an ablation threshold is reached where laser energy absorption is higher than that needed for evaporation. The ablation threshold is dependent on the absorption coefficient of the material and is thus wavelength dependent. At still hig
23、her fluences, absorption by the ablated species occurs, resulting in the formation of a plasma at the target surface. With appropriate choice of ablation wavelength and absorbing target material, high-energy densities are absorbed by a small volume of material, resulting in vaporization that is not
24、dependent on the vapor pressures of the constituent cations.In pulsed-laser deposition, a background gas is often introduced that serves two purposes. First, the formation of multication thin-film materials often requires a reactive species (e.g., molecular oxygen for oxides) as a component of the f
- 配套讲稿:
如PPT文件的首页显示word图标,表示该PPT已包含配套word讲稿。双击word图标可打开word文档。
- 特殊限制:
部分文档作品中含有的国旗、国徽等图片,仅作为作品整体效果示例展示,禁止商用。设计者仅对作品中独创性部分享有著作权。
- 关 键 词:
- PLD 脉冲 激光 沉积 简介 电子 教案
1、咨信平台为文档C2C交易模式,即用户上传的文档直接被用户下载,收益归上传人(含作者)所有;本站仅是提供信息存储空间和展示预览,仅对用户上传内容的表现方式做保护处理,对上载内容不做任何修改或编辑。所展示的作品文档包括内容和图片全部来源于网络用户和作者上传投稿,我们不确定上传用户享有完全著作权,根据《信息网络传播权保护条例》,如果侵犯了您的版权、权益或隐私,请联系我们,核实后会尽快下架及时删除,并可随时和客服了解处理情况,尊重保护知识产权我们共同努力。
2、文档的总页数、文档格式和文档大小以系统显示为准(内容中显示的页数不一定正确),网站客服只以系统显示的页数、文件格式、文档大小作为仲裁依据,平台无法对文档的真实性、完整性、权威性、准确性、专业性及其观点立场做任何保证或承诺,下载前须认真查看,确认无误后再购买,务必慎重购买;若有违法违纪将进行移交司法处理,若涉侵权平台将进行基本处罚并下架。
3、本站所有内容均由用户上传,付费前请自行鉴别,如您付费,意味着您已接受本站规则且自行承担风险,本站不进行额外附加服务,虚拟产品一经售出概不退款(未进行购买下载可退充值款),文档一经付费(服务费)、不意味着购买了该文档的版权,仅供个人/单位学习、研究之用,不得用于商业用途,未经授权,严禁复制、发行、汇编、翻译或者网络传播等,侵权必究。
4、如你看到网页展示的文档有www.zixin.com.cn水印,是因预览和防盗链等技术需要对页面进行转换压缩成图而已,我们并不对上传的文档进行任何编辑或修改,文档下载后都不会有水印标识(原文档上传前个别存留的除外),下载后原文更清晰;试题试卷类文档,如果标题没有明确说明有答案则都视为没有答案,请知晓;PPT和DOC文档可被视为“模板”,允许上传人保留章节、目录结构的情况下删减部份的内容;PDF文档不管是原文档转换或图片扫描而得,本站不作要求视为允许,下载前自行私信或留言给上传者【快乐****生活】。
5、本文档所展示的图片、画像、字体、音乐的版权可能需版权方额外授权,请谨慎使用;网站提供的党政主题相关内容(国旗、国徽、党徽--等)目的在于配合国家政策宣传,仅限个人学习分享使用,禁止用于任何广告和商用目的。
6、文档遇到问题,请及时私信或留言给本站上传会员【快乐****生活】,需本站解决可联系【 微信客服】、【 QQ客服】,若有其他问题请点击或扫码反馈【 服务填表】;文档侵犯商业秘密、侵犯著作权、侵犯人身权等,请点击“【 版权申诉】”(推荐),意见反馈和侵权处理邮箱:1219186828@qq.com;也可以拔打客服电话:4008-655-100;投诉/维权电话:4009-655-100。