Design And Characteristics Of ZnO Based Electroluminescent Devices

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.