CAREER: Engineering point defect formation in UWBG-based optoelectronic devices

职业：基于 UWBG 的光电器件中工程点缺陷的形成

• 批准号: 1653383
• 负责人: Ramon Collazo
• 金额: $ 50万
• 依托单位: North Carolina State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-03-01 至 2023-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1653383&HistoricalAwards=false
• 关键词: CAREER; Engineering; point; defect; formation

Many applications such as optoelectronics and power electronics rely on the functionality of ultra wide bandgap materials. But to reach their full potential, it is necessary to understand and realize novel processes to enhance their performance, either electrically or optically. The proposed processing framework has the opportunity of revolutionizing these family of materials, thus providing for the achievement of properties that otherwise will not be attainable. This is in addition to providing a unifying conceptual approach consistent with modern computational efforts that bring about a non-Edisonian approach to the design of materials and processes dealing with this class of materials. This research will directly lead to applications that deal with the preservation and extension of natural resources by allowing for: the availability of clean potable water through disinfection by the use of ultraviolet light emitting diodes, and the detection of pollutants and other effluents. The novel concepts developed within this project can also be implemented in the educational and outreach efforts (some specifically targeted at minority students), especially integrating materials characterization and control schemes to applications dealing with the need for the development of materials for sustainability purposes. This program will provide the opportunity to educate Ph.D. students on the growth, characterization and device fabrication of these materials while participating on an established international collaborators network. Furthermore, integration of these ideas into design of new courses broadens the community of students and experts related to the topic, especially those dealing with computational methods. From this, graduate students and group members will be able to effectively discuss their research for fruitful collaborations while accelerating their professional growth.Charged point defects in compound semiconductors strongly determine electronic and optical properties. The energy of formation of a point defect is a function of the process conditions and the Fermi energy. In ultra wide bandgap materials or insulators, the contribution of the Fermi energy to the formation energy of charged point defects is significant. For the practical case of doping for n- or p-type conductivity, the larger the energy gap, the higher the concentration of compensating point defects that is at equilibrium with the system. This is a fundamental problem of these materials that will be directly addressed with these capabilities. In this approach, we will extend the concept of the quasi-Fermi level in an effort to quantify the impact of external excitation in the formation energy of the point defect. Increasing the formation energy of unwanted point defect through external excitation during a growth experiment leads to a reduction in compensating point defects and higher device efficiencies. The research objective of this proposal is to test the hypothesis that the energy of formation of charged point defects could be manipulated by an external excitation in a steady-state condition during growth. Approaches include the introduction of above-bandgap illumination or e-beam irradiation as excitation sources. This process is referred to as Fermi level control of point defects. Three main research tasks are designed to test the hypothesis: (1) demonstration of Fermi level control of technologically important point defects during the growth of III-nitrides based UV LED structures, (2) optical and electrical study of point defects and their influence on the device performance, (3) extension to other wide bandgap systems and alternative Fermi level management processes to show universality of the process. This research will extend these capabilities to AlGaN for the engineered reduction of compensating and non-radiative defects in deep UV LEDs. It is expected that this process is generally applicable to a broad class of wide bandgap materials, in particular, several oxide systems.

光电子和电力电子等许多应用都依赖于超宽带隙材料的功能。但为了充分发挥其潜力，有必要了解并实现新颖的工艺来增强其电气或光学性能。所提出的加工框架有机会彻底改变这些材料系列，从而实现其他方式无法实现的性能。除此之外，还提供了一种与现代计算工作一致的统一概念方法，为材料设计和处理此类材料的工艺带来了非爱迪生方法。这项研究将直接导致涉及自然资源保护和扩展的应用，通过以下方式实现：通过使用紫外线发光二极管进行消毒来提供清洁的饮用水，以及检测污染物和其他废水。该项目中开发的新颖概念也可以在教育和推广工作中实施（有些专门针对少数族裔学生），特别是将材料表征和控制方案整合到处理可持续发展材料开发需求的应用中。该计划将提供博士学位教育的机会。学生在参与已建立的国际合作者网络的同时，了解这些材料的生长、表征和器件制造。此外，将这些想法整合到新课程的设计中扩大了与该主题相关的学生和专家的社区，特别是那些涉及计算方法的社区。由此，研究生和小组成员将能够有效地讨论他们的研究，以实现富有成效的合作，同时加速他们的专业发展。化合物半导体中的带电点缺陷在很大程度上决定了电子和光学特性。点缺陷的形成能量是工艺条件和费米能的函数。在超宽带隙材料或绝缘体中，费米能对带电点缺陷的形成能的贡献是显着的。对于 n 型或 p 型导电性掺杂的实际情况，能隙越大，与系统平衡的补偿点缺陷的浓度就越高。这是这些材料的一个基本问题，将通过这些功能直接解决。在这种方法中，我们将扩展准费米能级的概念，以量化外部激发对点缺陷形成能的影响。在生长实验期间通过外部激励增加不需要的点缺陷的形成能，从而减少补偿点缺陷并提高器件效率。该提案的研究目的是检验以下假设：带电点缺陷的形成能量可以通过生长过程中稳态条件下的外部激励来操纵。方法包括引入带隙以上照明或电子束照射作为激发源。这个过程被称为点缺陷的费米能级控制。设计了三项主要研究任务来检验这一假设：(1) 演示在 III 族氮化物 UV LED 结构生长过程中对技术上重要的点缺陷的费米能级控制，(2) 点缺陷的光学和电学研究及其对器件性能，（3）扩展到其他宽带隙系统和替代费米能级管理流程，以显示该流程的通用性。这项研究将这些功能扩展到 AlGaN，以工程方式减少深紫外 LED 中的补偿和非辐射缺陷。预计该工艺通常适用于多种宽带隙材料，特别是几种氧化物系统。

项目成果

Behavior of E. coli with Variable Surface Morphology Changes on Charged Semiconductor Interfaces

• DOI: 10.1021/acsabm.9b00573
• 发表时间: 2019-09-16
• 期刊: ACS APPLIED BIO MATERIALS
• 影响因子: 4.7
• 作者: Iyer, Divya;Gulyuk, Alexey, V;Ivanisevic, Albena
• 通讯作者: Ivanisevic, Albena

Recovery kinetics in high temperature annealed AlN heteroepitaxial films

• DOI: 10.1063/5.0002891
• 发表时间: 2020-03
• 期刊: Journal of Applied Physics
• 影响因子: 3.2
• 作者: S. Washiyama;Y. Guan;S. Mita;R. Collazo;Z. Sitar

Al Rich AlGaN Based APDs on Single Crystal AlN with Solar Blindness and Room Temperature Operation

单晶 AlN 上基于富铝 AlGaN 的 APD，具有日盲和室温操作功能

• DOI: 10.1109/rapid.2019.8864417
• 发表时间: 2019
• 期刊: 2019 IEEE Research and Applications of Photonics in Defense Conference (RAPID
• 作者: Reddy, Pramod;Collazo, Ramon;Sitar, Zlatko;Breckenridge, M. Hayden;Klump, Andrew;Guo, Qiang;Mita, Seiji;Sarkar, Biplab;Kirste, Ronny;Moody, Baxter
• 通讯作者: Moody, Baxter

Thermal conductivity of GaN single crystals: Influence of impurities incorporated in different growth processes

• DOI: 10.1063/1.5047531
• 发表时间: 2018-09
• 期刊: Journal of Applied Physics
• 影响因子: 3.2
• 作者: R. Rounds;B. Sarkar;T. Sochacki;M. Boćkowski;Masayuki Imanishi;Y. Mori;R. Kirste;R. Collazo;Z. Sitar

High p-conductivity in AlGaN enabled by polarization field engineering

• DOI: 10.1063/5.0143427
• 发表时间: 2023-04
• 期刊: Applied Physics Letters
• 影响因子: 4
• 作者: S. Rathkanthiwar;P. Reddy;B. Moody;Cristyan Quiñones-García;P. Bagheri;D. Khachariya;R. Dalmau