Surface Chemistry Studies During Thin-Film Growth Using Electrochemical Atomic Layer Epitaxy (EC-ALE)

使用电化学原子层外延 (EC-ALE) 进行薄膜生长过程中的表面化学研究

• 批准号: 0075868
• 负责人: John Stickney
• 金额: $ 37.66万
• 依托单位: University of Georgia Research Foundation Inc
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-08-01 至 2003-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0075868&HistoricalAwards=false
• 关键词: Surface; Chemistry; Studies; During; Thin

The goal of this project is greater understanding and control of electrochemical epitaxial processing of compound semiconductors. The focus of the project is atomic layer epitaxy (ALE), where deposits are formed an atomic layer at a time. In ALE, surface limited reactions are used to form each atomic layer. Surface limited electrochemical reactions generally occur at underpotentials, potentials below those needed to deposit the element on itself. The approach makes use of an automated electrochemical flow-cell, which facilitates growth of films thick enough for analysis by X-ray diffraction (XRD), electron microprobe analysis (EPMA), infrared (IR), and optical spectroscopies. Previous EC-ALE studies have focused either on the first few atomic layers or the structure, composition, and morphology of completed films. This project will address surface chemistry of the EC-ALE cycle as the deposit is being formed. It is thought that optimal conditions (potentials) change as the deposit grows, and some form of feedback is needed to better control the process. However, currents measured during various cycle steps do not provide an accurate picture of the deposition process. It is proposed to study the surface chemistry after various numbers of cycles, and at different points in the cycle, while deposits are forming, that is, to follow the surface chemistry during the 2nd , 5th , 10th , 25th , -..200th , cycles. Surface sensitive probes will be used to follow the EC-ALE cycle chemistry during film growth. A unique electrochemical STM flow-cell will be used to monitor surface structure and morphology during deposition. This apparatus allows atomic scale imaging in a controlled environment where solutions are easily exchanged and EC-ALE deposits can be formed. The mass of the deposits will be monitored at each step in the EC-ALE cycle using an electrochemical quartz crystal microbalance (EC-QCM) system. A microbalance crystal will be used as a substrate in a flow-cell. The mass of the deposit at each step will be compared with observed currents to elucidate interfacial processes and current efficiencies. An electrochemical flow-cell deposition system will be constructed for use in the antechamber of a UHV surface system, so that the composition of the surface can be monitored after any number of cycles and after any cycle step. Deposits will be transferred periodically from the flow cell directly to the analysis chamber for examination with AES, XPS, LEED, STM, and LEIS. Improved understanding of the surface chemistry, leading to better control over deposit structure, composition and morphology is expected. InAs and InSb are being grown using EC-ALE and work on the formation of III-V compounds in general will continue. CdSe/CdTe and InAs/InSb superlattices have been formed, and will continue to be studied.%%%The project addresses basic research issues in a topical area of materials science with high technological relevance. New, innovative experimental techniques such as electrochemical atomic layer epitaxy can now be characterized more fully leading to greater understanding and control of elementary chemical and diffusion processes which will allow advances in fundamental materials science and technology. The basic knowledge and understanding gained from the research is expected to contribute to improving the ability to efficiently deposit high crystal quality semiconductor films for electronic and photonic applications. An important feature of the program is the integration of research and education through the training of students in a fundamentally and technologically significant area.***

该项目的目的是对复合半导体的电化学外延处理的更深入和控制。该项目的重点是原子层外延（ALE），其中一个沉积物一次形成原子层。在啤酒中，表面有限反应用于形成每个原子层。表面有限的电化学反应通常发生在义务范围内，低于沉积元件所需的电位。该方法利用自动化的电化学流量细胞，该电池促进了足够厚的膜的生长，以通过X射线衍射（XRD），电子微探针分析（EPMA），红外线（IR）和光谱光谱法分析。先前的EC-ALE研究集中在前几个原子层或完整膜的结构，组成和形态上。该项目将随着矿床的形成，将解决EC-ale循环的表面化学。人们认为，随着存款的增长，最佳条件（潜在）会发生变化，并且需要某种形式的反馈来更好地控制过程。但是，在各个循环步骤中测得的电流并不能准确地描述沉积过程。提议在各种循环数量后研究表面化学，在周期中的不同点处，即沉积物在形成时，即在第二，第5、10、25、25，.. 200th Cycles遵循表面化学。表面敏感的探针将用于遵循膜生长期间的EC-ale循环化学。独特的电化学STM流量细胞将用于监测沉积过程中的表面结构和形态。该设备允许在受控环境中易于交换溶液并形成EC-ale沉积物的原子尺度成像。将使用电化学石英晶体微量平衡（EC-QCM）系统在EC-ale循环中的每个步骤中监测沉积物的质量。微平衡晶体将用作流细胞中的底物。每个步骤的沉积物质量将与观察到的电流进行比较，以阐明界面过程和电流效率。将构建电化学流量细胞沉积系统，用于在UHV表面系统的横切室中使用，以便在任何数量的周期和任何周期步骤之后都可以监测表面的组成。沉积物将定期从流动池转移到分析室进行AES，XPS，LEED，STM和LIEW检查。对表面化学的了解得以提高，从而可以更好地控制沉积结构，组成和形态。 INAS和INSB正在使用EC-ale生长，并在一般来说，在III-V化合物的形成方面都将继续进行。 CDSE/CDTE和INAS/INSB超级晶格已经形成，并将继续研究。%%%该项目解决了具有高技术相关性的材料科学主题领域的基础研究问题。现在，可以更充分地表征新的创新实验技术，例如电化学原子层的外观，从而更加充分地了解基本化学和扩散过程，从而可以在基本材料科学和技术方面取得进步。预计从研究中获得的基本知识和理解力有助于提高有效地为电子和光子应用沉积高晶体质量半导体膜的能力。 该计划的一个重要特征是通过培训学生在根本和技术意义的领域中培训研究和教育。***