【作者】 刘威；

【导师】 徐春祥； 石增良；

【作者基本信息】 东南大学 ， 生物医学工程， 2021， 博士

【摘要】 紫外电致发光器件可被广泛应用于生物医学工程、光电子与信息技术等领域。ZnO因其直接带隙、宽禁带（3.37 e V）及高激子束缚能（60 me V）等优点,成为紫外光电子器件的优选材料之一。但由于难以获得稳定性好、载流子浓度高的p型ZnO,近年来研究者针对ZnO/Ga N异质结发光二极管开展了大量的研究,重点围绕改变异质结的结构以及引入表面等离激元等。由于器件结构和增益材料性质是决定器件性能的关键因素。因此,合理设计器件的结构和提升增益材料的性能对于提高器件的性能显得尤为重要,更有利于提高其在原有领域的应用效率甚至拓宽新的应用领域。本文旨在合理设计ZnO基电致发光器件的结构和优化ZnO的性能,从而制备出高发光效率、高亮度以及多功能的ZnO基电致发光器件。本文的主要研究内容如下:1.对称双异质结发光二极管的制备。选取ZnO微米线为增益材料,设计了n-ZnO/n-Ga N/n-ZnO和n-ZnO/p-Ga N/n-ZnO对称双异质结,研究了其在直流电正反方向单个异质结的发光特性以及器件的整体发光特性,利用I-V特性和光谱分析了器件在不同频率交流电激励下的电学特性和发光特性,发现该结构发光二级管不仅能够在交流激励下正常工作,而且有效消除了频闪效应,解决了现有二极管不能直接在交流电激励下工作以及频闪的问题。研究器件的电流响应速度,发现响应频率较高,并将其应用于光通讯领域。2.异质结二极管界面发光的调控。设计引入超薄Hf O₂电子阻挡层至n-ZnO/p-Ga N异质结,实现了界面发射从414 nm至394 nm的调控,将对异质结器件的无用的界面发射变为可用,有效提高了器件的发光效率,获得了高质量的纯紫外电致发光器件,并探讨了其电子隧穿的机制。另外,结合电容理论计算分析了器件的电子电流密度分布以及载流子输运特性,发展了一种基于电容判断介质层属性的简便方法。3.调控和引入缺陷改善ZnO基电致发光器件的性能。研究了热辅助紫外辐照方法对ZnO微米线的缺陷、光致发光以及电致发光的影响,分析了热辅助紫外辐照对ZnO微米线中氧空位和锌间隙缺陷的抑制作用以及对辐射复合效率的提升,有效提高了ZnO微米线及其电致发光器件的发光性能。通过引入Er³⁺掺杂,分析了其对ZnO微米线的电导率及发光性能的调控,有效提升了其电致发光器件的发光强度和效率。4.基于ZnO微米线缺陷调控温度传感器的构建。系统研究了温度与ZnO微米线荧光强度、电导率之间的关系,分别构建了基于荧光强度和电流强度的温度传感器,探讨了材料缺陷、温度与荧光强度或电导率之间的关联机制,并分析了温度传感器的热敏电阻系数和相对灵敏度,实现了在人体体温区间的传感应用。更多还原

【Abstract】 Ultraviolet electroluminescent devices are widely used in multiple fields such as biomedical engineering,optoelectronics and information technology.ZnO has become one of the preferred materials for ultraviolet optoelectronic devices due to its direct band gap,wide band gap（3.37 e V）and high exciton binding energy（60 me V）,However,due to its great difficulty to obtain p-type ZnO with good stability and high carrier concentration,researchers have carried out a lot of research on ZnO/Ga N heterojunction light-emitting diodes,which focused on changing the structure of the heterojunction and introducing surface plasmon in recent years.The device structure and gain-material properties are the key factors of the performance of the device,therefore.Rationally designing the structure of the device and improving the performance of the gain-material are particularly important for improving the performance of the device,which is more conducive to improving its application efficiency in the original field and even broadening new application fields.This article aims to rationally design the structure of ZnO-based electroluminescent devices and optimize the performance of ZnO,so as to prepare ZnO-based electroluminescent devices with high luminous efficiency,high brightness and multi-function.The main research contents of this article are as follows:1.The preparation of symmetrical double heterojunction light-emitting diodes.This article selected ZnO microwires as gain materials,and designed n-ZnO/n-Ga N/n-ZnO and n-ZnO/p-Ga N/n-ZnO symmetric double heterojunctions,and studied the luminescence characteristics of a single heterojunction in the forward and reversed directions of direct current as well as the overall luminescence characteristics of the device.Using I-V characteristics and spectrum to analyze the electrical characteristics and luminescence characteristics of the device under AC excitation at different frequencies,we found that the structure of the light-emitting diode can not only work normally under AC excitation,but also effectively eliminate the stroboscopic effect,which solved the problems that the existing diode cannot work directly under the excitation of alternating current and the stroboscopic problem.The current response speed of the device is studied.It is found that the response frequency is higher,which can be applied to the field of optical communication.2.Regulation of light emission on the interface of heterojunction diodes.The design introduces an ultra-thin Hf O2 electron barrier layer into the n-ZnO/p-Ga N heterojunction,which realizes the regulation of the interface emission from 414 nm to394 nm,and makes the useless interface emission of the heterojunction device available,and effectively improves the luminous efficiency of the device.Then,a high-quality pure ultraviolet electroluminescence device was obtained,and the mechanism of electron tunneling was discussed.In addition,the electronic current density distribution and carrier transport characteristics of the device are analyzed by capacitance theory calculations,and a simple method for judging the properties of the dielectric layer based on capacitance has been developed.3.Regulation and introduction of defects to improve the performance of ZnO-based electroluminescent devices.The effects of heat-assisted ultraviolet irradiation on the defects,photoluminescence and electroluminescence of ZnO microwires were studied.The suppression effect of heat-assisted ultraviolet irradiation on the oxygen vacancies and zinc interstitial defects in ZnO microwires and the radiation recombination were analyzed,which effectively improved the luminous performance of ZnO microwires and ZnO based electroluminescent devices.The regulation of the conductivity and luminescence performance of the ZnO microwire was analyzed by introducing Er³⁺doping,which improved the luminous intensity and efficiency of the electroluminescent device.4.Construction of temperature sensor based on defect regulation of ZnO microwire.The relationships among the temperature,the fluorescence intensity and conductivity of the ZnO microwire were systematically studied,and temperature sensors based on fluorescence intensity and current intensity were constructed respectively.The correlation mechanism between material defects,temperature and fluorescence intensity or conductivity was discussed,and the thermistor coefficient and relative sensitivity of the temperature sensor are analyzed,which is the basis of realizing the sensing application in the human body temperature range.更多还原