Materials Processing for ZnO

本项目主要研究两个领域，一是利用氧化锌作为材料欧姆接触的工艺材料，二是探索和开发掺杂氧化锌的铁磁性。更深入地了解与稳定、低阻的氧化锌欧姆接触有关的基础材料科学；用于干法刻蚀氧化锌的等离子体化学；用于接触形成和器件内电气和光学隔离的选择性区域掺杂所需的注入/隔离；以及氢对氧化锌的电和磁性能的作用。该项目的基本原理包括将氧化锌应用于紫外光发射器、压敏电阻、透明高功率电子器件、表面声波器件、压电换能器、气敏以及作为显示器和太阳能电池的窗口材料。与GaN相比，它具有更大的激子结合能(~60 meV，cf.GaN约为25 meV)。此外，在In组分~22%的情况下，ZnO与InGaN是晶格匹配的，这增加了两种材料集成以提供增强功能的可能性。这可能会在高密度数据存储系统、固态照明(其中白色光是从蓝色或紫外光发光二极管激发的荧光粉中获得)、硫化通信和生物检测中得到应用。氧化锌的性质与氮化镓的性质相当。氧化锌是一种Eg=3.2 eV的直接带隙半导体。带隙可以通过阳离子位置上的二价取代来调节。Cd替代导致禁带宽度减小到约3.0 eV。在锌位上替代镁可以使带隙增加到约4.0 eV，同时仍保持纤锌矿结构。室温下，氧化锌单晶的电子霍尔迁移率约为200cm2/V-sec量级。电子迁移率略低于GaN，但具有较高的饱和速度。这个项目解决了材料科学中与重大技术相关的主题领域的基础研究问题，并强调研究和教育的整合。至少两名本科生将被包括在这个项目中。将特别鼓励来自代表性不足群体(妇女、少数群体)的人参加。此外，作为这次助学金活动的一部分，PI将接待2名学生参加由UFL大学学前教育和培训中心在夏季举办的UFL学生科学培训计划。该计划目前已进入第41个年头，吸引了10年级和11年级的学生积极参与科学和工程研究。佛罗里达大学的学前教育和培训中心还在夏季开展了一项NSF教师研究更新经验(TRUE)计划。国际学生联合会将在该项目上发表关于氧化锌的演讲，并将与感兴趣的教师合作，将这里的研究经验转化为模块，可以带回初中和高中。***

This project focuses on two research areas related to utilization of ZnO as a technological mate-rial-ohmic contact formation, and the exploration and potential exploitation of ferromagnetism in doped ZnO. Greater understanding of fundamental materials science associated with stable, low resistance ohmic contacts to ZnO; plasma chemistries for dry etching of ZnO; implanta-tion/isolation needed in selective area doping for contact formation and for intra-device electrical and optical isolation; and the role of hydrogen on electrical and magnetic properties of ZnO is sought. Rationale for the project includes potential ZnO application to UV light emitters, varistors, transparent high power electronics, surface acoustic wave devices, piezoelectric transducers, gas-sensing and as a window material for display and solar cells. It has advantages relative to GaN because of its availability in bulk, single crystal form and its larger exciton binding energy (~60meV, cf. ~25meV for GaN). In addition, ZnO is lattice-matched to InGaN at an In composition of ~22%, raising the possibility of integration of the two materials to provide enhanced functionality. This may have applications in high-density data storage systems, solid-state lighting (where white light is obtained from phosphors excited by blue or UV light-emitting diodes), se-cure communications and biodetection. The properties of ZnO compare well with those of GaN. ZnO is a direct bandgap semiconductor with Eg = 3.2 eV. The bandgap can be tuned via divalent substitution on the cation site. Cd substitution leads to a reduction in the bandgap to ~ 3.0 eV. Substituting Mg on the Zn site can increase the bandgap to approximately 4.0 eV while still maintaining the wurtzite structure. The electron Hall mobility in ZnO single crystals is on the order of 200 cm2/V-sec at room temperature. The electron mobility is slightly lower than for GaN, but ZnO has a higher saturation velocity. %%% 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. At least two undergraduates will be included in this project. Persons from under-represented groups (women, minorities) will be particularly encouraged to participate. Additionally, as part of this grant activity, the PI will host 2 students attending the U. FL Student Science Training Program, which is run during the summer by the U. FL Center for Precollegiate Education and Training. This program, now in its 41st year, brings in 10th and llth grade students to actively participate in science and engineering research. The Center for Precollegiate Education and Training at the University of Florida also runs an NSF Teacher Research Update Experience (TRUE) program during the summer. The PI will present a lecture on ZnO at the program and will collaborate with interested teachers to translate the research experience here into modules, which can be taken back to the middle and high schools. ***