Carrier Doping in Epitaxial (Zn,Mg)O Thin Films

本计画主要研究（Zn，Mg）O的n型与p型掺杂控制，以应用于宽禁带电子学。该方法包括载流子掺杂的（Zn，Mg）O晶体薄膜的合成和性能，重点是理解外延（Zn，Mg）O薄膜中受主和施主态的形成。感兴趣的合金组合物包括可以实现纯相纤锌矿结构的富Zn区域，以及获得岩盐结构的富Mg区域。目的是了解掺杂剂种类，复杂的形成，并结合激活掺杂剂的生长条件的作用。活动将包括使用两种互补的外延膜生长技术进行掺杂研究。首先，将使用分子束外延研究V族受体（主要是N）的阴离子掺杂。已经对单氮与多氮承载分子作为氮掺杂的递送物质的有效性进行了具体的理论预测。Zn间质、氧空位和/或氢络合物在形成补偿浅施主能级中的作用使得需要同时考虑原位和生长后处理条件的作用。第二，脉冲激光沉积将用于研究受主掺杂和施主掺杂的（Zn，Mg）O。施主掺杂剂将是在阳离子位点上取代的III族元素（Ga）。对于使用脉冲激光沉积的受体掺杂，主要焦点将是磷掺杂，因为最近的结果表明，在重P掺杂的ZnO表面的p型行为。还已经预测，与某些供体杂质共掺杂可能由于形成受体-供体-受体络合物而导致受体能级的降低。作为p型掺杂的第二种选择，将考虑共掺杂方法，重点是确定深受主能级是否可以通过形成受主-施主-受主复合物转移到较低的能量。温度依赖霍尔，塞贝克，C-V和电阻率测量将用于确定导电机制，载流子类型和掺杂。低温光致发光和导纳光谱将用于确定给定掺杂剂的受主能级的位置。用X射线衍射仪表征薄膜的结晶度。.%%% 该项目涉及材料科学领域的基础研究问题，具有重要的技术相关性，并强调研究和教育的整合。项目活动将包括开发电子氧化物物理和材料的教程，作为材料科学和物理研究生系列研讨会的一部分。它将每年由PI或参与研究的研究生提交。演示材料将张贴在指定的网站上，从而为研究人员和学生以外的佛罗里达大学提供访问。为了提高本科生接触氧化物电子学和一般研究，该研究项目将通过现有的高级研究论文计划纳入公司本科生。每年，一个四年级的材料科学与工程本科生将被招募选择一个氧化物电子相关的项目作为他或她的高级论文研究课题。将特别鼓励代表不足的群体（妇女、少数群体）的人士参加。

This project addresses controlled n-type and p-type doping of (Zn,Mg)O for wide bandgap elec-tronics. The approach includes the synthesis and properties of carrier-doped (Zn,Mg)O crystalline thin films with a focus on understanding the formation of acceptor and donor states in epitaxial (Zn,Mg)O thin films. The alloy compositions of interest include the Zn-rich region for which the phase-pure wurtzite structure can be realized, as well as the Mg-rich region where the rock-salt structure is obtained. The objective is to understand the role of dopant species, complex forma-tion, and growth conditions on the incorporation of activated dopants. Activities will include the study of doping using two complementary epitaxial film-growth techniques. First, anion doping with group V acceptors (primarily N) will be investigated using molecular beam epitaxy. Specific theoretical predictions have been made regarding the effectiveness of single nitrogen versus multi-nitrogen bearing molecules as the delivery species for nitrogen doping. The role of Zn in-terstitials, oxygen vacancies, and/or hydrogen complexes in forming compensating shallow donor levels imposes the need to simultaneously consider the role of in situ and post-growth processing conditions. Second, pulsed-laser deposition will be used to investigate both acceptor doping and donor doping of (Zn,Mg)O. The donor dopant will be a group III element (Ga) substituted on the cation site. For acceptor doping using pulsed laser deposition, the primary focus will be on phos-phorus doping, as recent results suggest p-type behavior in heavily P-doped ZnO surfaces. It has also been predicted that co-doping with certain donor impurities may lead to a lowering of the acceptor levels due to the formation of acceptor-donor-acceptor complexes. As a secondary op-tion to p-type doping, co-doping approaches will be considered, with the focus on determining whether deep acceptor levels can be shifted to lower energies via the formation of acceptor-donor-acceptor complexes. Temperature-dependent Hall, Seebeck, C-V, and resistivity meas-urements will be used to determine conduction mechanisms, carrier type, and doping. Low tem-perature photoluminescence and admittance spectroscopy will be used to determine the location of the acceptor level for a given dopant. X-ray diffraction will used to characterize film crystal-linity. .%%% This project addresses basic research issues in a topical area of materials science with significant technological relevance, and places emphasis on the integration of research and education. Pro-ject activities will include developing a tutorial on Electronic Oxide Physics and Materials to be delivered as part of the Graduate Student Seminar Series in both Materials Science and Physics. It will be presented on an annual basis either by the PI or the graduate students involved in the re-search. The presentation materials will be posted on a designated website, thus providing access for researchers and students outside the University of Florida. In order to enhance the exposure of undergraduate students to oxide electronics, and research in general, the research project will in-corporate undergraduates through an existing Senior Research Thesis program. Each year, a fourth-year Materials Science and Engineering undergraduate student will be recruited to select an oxide electronics-related project as his or her Senior Thesis research topic. Persons from un-der-represented groups (women, minorities) will be particularly encouraged to participate.***