ZnO微米晶的激光制备装置及发光性能研究

Laser-Induced Growth Device and Optical Properties of ZnO Microcrystals

ZnO是第三代半导体的代表之一,可作为紫外光致发光与多共振模式激光的载体,尤其以光学气化过饱和析出法(OVSP)制备的ZnO微米晶近年来在光催化、高效多彩光源、高效电致发光等方面显示出重要优势,但其制备成本较高、生产效率低下,阻碍了其大规模器件化的发展。针对上述问题,基于有限元分析的结果,设计并搭建了一套工作波长在1080nm,功率18%(@2500W)激光加热的微米晶生长装置。以ZnO为原料验证了所研制装置的可行性与实用性。结果表明,该装置制备产物与OVSP法制备产物在形貌、结构、发光性能上非常接近,生产效率得到极大提高(~500%)。利用研制的生长装置,成功制备出了具有完整六边形截面形貌的富受主型ZnO单晶微米棒,其直径约为3.8μm,长度达10~20μm。通过拉曼光谱发现,ZnO微米棒的拉曼峰清晰尖锐,位于437cm^(-1)处的拉曼峰对应E_(2)^(high)模式,所制备微米棒为结晶性较好的六方纤锌矿结构。通过对ZnO微米棒荧光光谱的分析,发现其与OVSP法所制备的ZnO微米管具有类似的紫外双峰结构,表明微米棒内存在大量与锌空位(V_(Zn))相关的受主缺陷。在80~280K范围内,随着温度升高,ZnO微米棒的荧光发光峰强度出现“热猝灭-负热猝灭-热猝灭”的反常行为。研究发现,在166~200K范围内出现的负热猝灭行为与导带底以下477meV处存在的中间态能级(陷阱中心)有关,在200~280K范围内出现的热猝灭现象与导带底以下600meV处非辐射复合中心有关。两者的出现与所制备的ZnO微米棒氧空位(V_(Zn))缺陷相关。所研制的激光生长装置具有较高的可行性与实用性,该制备方法为富受主型ZnO单晶微米棒的快速批量生长奠定了技术基础,同时对其在光电器件领域的应用也具有重要意义。

ZnO is third-generation semiconductors which can be used as the carrier of ultraviolet photoluminescence and multiresonance mode laser.In recent years,ZnO microcrystals prepared by optical vapor supersaturation precipitation(OVSP)have shown important advantages in photocatalysis,efficient multi-color light source and efficient electroluminescence.However,the high preparation cost and low production efficiency hinder the development of the large-scale device.In this work,we designed and built a set of growth devices with a working wavelength of 1080nm and a power of 18%(@2500 W)laser heating.The height of the raw material rod was 6.5mm,and the diameter was 8mm.The results show that the morphology,structure,and luminescence properties of the products prepared by this device are very close to those prepared by the OVSP method,and the production efficiency is greatly improved(~500%).The growth device successfully prepared acceptor-rich ZnO single crystal micro rods with complete hexagonal cross-section morphology.The diameter and length of ZnO micro rods are about 3.8and10~20μm,respectively.Raman spectra show that the Raman peaks of ZnO micro rods are sharp,and the Raman mode at 437cm^(-1)indicates that the ZnO micro rods are hexagonal wurtzite structures with good crystallinity.By analysing the PL spectra of ZnO micro rods,it was found that the ZnO microtubes prepared by the OVSP method had a similar ultraviolet bimodal structure,indicating that there exists an abundant zinc-vacancies acceptor.In the 80~280Krange,with the increase of temperature,the fluorescence intensity of ZnO microrods appears“thermal quenching-negative thermal quenching-thermal quenching”behavior.The negative thermal quenching behavior in the range of 166~200 Kis related to the intermediate state energy level(trap center)at 477meV below the conduction band bottom,and the thermal quenching phenomenon in the range of 200~280Kis related to the non-radiative recombination center at 600 meV below the conduction band bottom.The appearance of both is related to the prepared ZnO microrod oxygen vacancy(V_(O))defect.The laser growth device developed in this paper has high feasibility and practicability.This preparation method lays a technical foundation for the rapid batch growth of ZnO single crystal micro rods with rich acceptors and is also of great significance for its application in optoelectronic devices.