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

本项目研究宽禁带电子器件中（Zn,Mg）O的可控n型和p型掺杂。该方法包括载流子掺杂（Zn,Mg）O晶体薄膜的合成和性能，重点了解外延（Zn,Mg）O薄膜中受体和施主态的形成。感兴趣的合金成分包括富锌区，其中可以实现相纯纤锌矿结构，以及富镁区，其中获得岩盐结构。目的是了解掺杂剂种类、复合物形成和生长条件对活性掺杂剂掺入的作用。活动将包括使用两种互补的外延薄膜生长技术研究掺杂。首先，阴离子掺杂与V族受体（主要是N）将研究分子束外延。对单氮与多氮承载分子作为氮掺杂的传递种的有效性进行了具体的理论预测。锌在基质内、氧空位和/或氢配合物在形成补偿浅层供体水平中的作用，要求同时考虑原位和生长后加工条件的作用。其次，脉冲激光沉积将用于研究（Zn,Mg）O的受体掺杂和供体掺杂。供体掺杂剂将是取代在阳离子位上的III族元素（Ga）。对于使用脉冲激光沉积的受体掺杂，主要焦点将放在磷-磷掺杂上，因为最近的结果表明在高p掺杂的ZnO表面上存在p型行为。也有人预测，与某些供体杂质共掺杂可能会由于形成受体-供体-受体复合物而导致受体水平的降低。作为p型掺杂的第二选择，将考虑共掺杂方法，重点是确定是否可以通过形成受体-供体-受体复合物将深层受体水平转移到较低的能量。温度相关的霍尔，塞贝克，C-V和电阻率测量将用于确定传导机制，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体能级的位置。x射线衍射将用来测定薄膜的结晶度。本项目涉及材料科学中具有重要技术相关性的主题领域的基础研究问题，并强调研究与教育的整合。项目活动将包括开发电子氧化物物理和材料教程，作为材料科学和物理学研究生系列研讨会的一部分。它将由PI或参与研究的研究生每年提交一次。演示材料将发布在指定的网站上，从而为佛罗里达大学以外的研究人员和学生提供访问权限。为了提高大学生对氧化物电子学的了解，以及总体上的研究，该研究项目将通过现有的高级研究论文计划在企业本科生中进行。每年招收一名四年级材料科学与工程本科学生，选择一个氧化物电子相关项目作为他或她的毕业论文研究课题。将特别鼓励代表性不足的群体（妇女、少数民族）的人参加

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.***