Control of Defect Interactions for P-Type Doping of ZnO by Ion Implantation

这是一个少数民族职业发展奖（MCAA）项目，研究p型透明导电氧化物（tco）和宽带隙半导体的选择性区域形成，使用离子注入，重点研究ZnO作为代表材料。掺杂方法涉及在足够低的温度下进行离子注入，以冻结由离子束辐照产生的间隙，从而避免产生缺陷不平衡，从而妨碍对注入引起的晶格损伤进行适当的退火。低温注入后，对样品进行快速的原位加热，以诱导短范围、间隙-空位复合和掺杂剂的取代晶格位置。然后将进行非原位退火以进一步退火任何残留的晶格缺陷，并增强掺杂剂的电活化。通过控制缺陷的迁移率和重组，通过仔细监测潜在掺杂剂的晶格位置，以及植入层的电输运性质，寻求有关ZnO和其他宽带隙半导体中常见掺杂困难的机制的基本信息。注入和退火样品将表征其结构，组成，光学和电子输运性质。晶格无序度和掺杂浓度作为深度函数的测量将被执行，并与光学和电子输运分析相关联：卢瑟福后向散射光谱将被用于确定化学计量、成分作为深度函数和薄膜中杂质的存在。离子通道测量将用于监测注入引起的晶格损伤，并评估（在单晶中）掺杂剂的晶格位置。离子注入物种的深度分布，以及宿主底物成分和杂质，将用二次离子质谱法研究。光学性质将通过分光光度法分析，在传输和反射模式。电子输运性质将通过霍尔效应和电导率测量来表征，作为温度的函数。这项研究有望促进对ZnO和其他宽带隙半导体的电输运特性的理解，并为ZnO基器件的空间控制掺杂开发一种方法。该项目涉及与具有技术相关性的电子材料相关的基础研究问题。该项目的一个重要特点是科研与教育的结合。通过对本科生和研究生进行材料研究主题和方法的教育和培训，可以举例说明与该项目相关的更广泛影响；将研究活动中开发的材料纳入研究生/本科生关于离子-固体相互作用的课堂；强调吸引来自代表性不足群体的学生；与来自拉丁美洲的团体建立科学合作；促进学生（研究生、本科生、高中）的活动，如技术专题讨论会和地方一级的海报比赛（佛罗里达州）；与奥兰多科学中心合作为高中和初中科学教师举办科学讲习班；公布研究结果，并在指定网站（物理系网站：www.physics.ucf.edu）公布科学信息。

This is a Minority Career Advancement Award (MCAA) project addressing selective-area formation of p-type transparent conducting oxides (TCOs), and wide band gap semiconductors, using ion implantation, with focus on ZnO as a representative material. The doping approach involves ion implantation at a temperature low enough to freeze interstitials created by ion beam irradiation so as to avoid creation of a defect imbalance that precludes proper annealing of implantation-induced lattice damage. Low temperature implantation will be followed by a very rapid in-situ heating of the sample, to induce short range, interstitial-vacancy recombination, and substitutional lattice location of the dopants. An ex-situ annealing will then be carried out to further an-neal any residual lattice defects, and enhance electrical activation of the dopants. By controlling the mobility and recombination of defects, and by carefully monitoring the lattice location of po-tential dopants, and the electrical transport properties of the implanted layers, fundamental in-formation is sought regarding mechanisms responsible for the doping difficulties typically encountered in ZnO, and other wide band gap semiconductors. Implanted and annealed samples will be characterized for their structural, compositional, optical, and electronic transport properties. Measurements of lattice disorder and dopant concentration as a function of depth, will be performed and correlated with optical and electronic transport analyses: Rutherford backscattering spectrometry will be employed to determine stoichiometry, composition as a function of depth, and the presence of impurities in the films. Ion channeling measurements will be used to monitor implantation induced lattice damage, and to assess the lattice location of the dopants (in single crystals). The depth profiles of ion implanted species, as well as host substrate compo-nents, and impurities, will be studied with secondary ion mass spectrometry. Optical properties will be analyzed by spectrophotometry, in transmission and reflection modes. Electronic trans-port properties will be characterized by Hall effect and conductivity measurements, as a function of temperature. This research is expected to advance understanding of the role of defects on the electrical transport properties of ZnO, and other wide band gap semiconductors, and in the de-velopment of an approach for spatially controlled doping of ZnO based devices. %%% The project addresses fundamental research issues associated with electronic materials having technological relevance. An important feature of the project is the integration of research and education. Broader impacts associated with the project are exemplified by education and training of undergraduate and graduate students in materials research topics and methodologies; incorporation of the materials developed in the research activity in a graduate/undergraduate class on ion-solid interactions; a strong emphasis on attracting students from underrepresented groups; establishment of scientific collaborations with groups from Latin America; fostering of activities for students (graduate, undergraduate, high school) such as technical symposia and poster session competitions at the local level (Florida State); development of science workshops for high and middle school science teachers in collaboration with Orlando Science Center; and dissemination of scientific information by publishing the results, and posting on a designated website (within the Physics Department website: www.physics.ucf.edu).