Field emission enhancement of composite structure of ZnO quantum dots and CuO nanowires by Al2O3 transition layer optimization

Significance 

Although of the advancement in the field, the application of ZnO quantum dots is still limited by their poor charge transport performance. With the rapid advancement in nanotechnology, one-dimensional oxide nanostructures such as nanowires have been widely used for field emission-related studies. These nanomaterials exhibit significant coupling effects with ZnO quantum dots due to the latter’s remarkably large surface-to-volume ratio property. As such, a composite of ZnO quantum dots and one-dimensional oxide nanostructures have been widely speculated to be a potential material for efficient field emission enhancement. However, no definitive studies have been conducted to prove these assertions.

Recent studies revealed that the field emission properties could be significantly increased by nanowires with core-shell heterostructures. Consequently, heterostructures formed from different functional components have been found to bring new interface effects that can further improve the properties and functions of these materials. Equipped with this knowledge, Dr. Lei Sun, Dr. Enguo Chen, and Mr. Tailiang Guo from Fuzhou University explored the field emission enhancement capability of the composite structure of ZnO quantum dots and CuO nanowires synthesized by a mild solution method. The main objective was to investigate the field emission properties of the synthesized heterojunction composite structures. Their research work is currently published in the journal, Ceramics International.

In their approach, the Al2O3 transition layer was adopted as a good nucleation interface for the growth of ZnO, and it was deposited on the CuO nanowires by surface modification engineering technique. The modification process was specifically based on atomic layer deposition to enhance the surface characteristics of the CuO nanowire substrate and microstructure of the ZnO quantum dots. The structural morphology and composition of the prepared conducts, as well as their field emission properties, were studied in detail using various techniques such as scanning electron microscopy (SEM) and transmission electron microscopy.

The authors reported a significant improvement in the field emission performance of the [email protected]2O3/ZnO ternary heterostructure compared to pure CuO nanowires and ZnO quantum dots-CuO nanowires. For instance, the synthesized ternary heterostructure reported a field enhancement factor of 5798 and a turn-on field of 2.82 V/µm. The remarkable improvement in the field emission site stability and the electron conductivity was attributed to the easy transportation of electrons to the ZnO quantum dots due to the increase of the oxygen vacancies and the decrease of the electron transport barrier at the interface. Moreover, the amorphous Al2O3 transition layer also helped minimize the lattice mismatch between the substrate and ZnO quantum dots.

In summary, the authors investigate the field emission performance of ZnO quantum dot-CuO heterostructure nanowires synthesized by the mild solution method. Results showed improvement in performance with enhanced electronic conductivity and field emission site stability. In a statement to Advances in Engineering, the authors said their study would pave the way for the use of core-shell heterostructure nanomaterials for improving field emission performance.

Field emission enhancement of composite structure of ZnO quantum dots and CuO nanowires by Al2O3 transition layer optimization - Advances in Engineering

About the author

Enguo Chen is currently an associate professor at Fuzhou University, with a joint appointment as a Distinguished Research Fellow of Fujian Science & Technology Innovation Laboratory for Optoelectronic Information of China. He received his Ph.D. from Zhejiang University, China in 2013. After that, he visited The Hong Kong University of Science and Technology (HKUST) and University of Central Florida (UCF) as a research scholar, respectively.

His research interests mainly include: 1) optical design of optical systems, 2) emerging display technologies. Till now his research has been funded by several grants from national or regional government, and he has also cooperated with several well-known display manufacturers.

He has published over 70 papers in academic journals and conference proceedings, and owned over 30 authorized Chinese invention patents. He is member of OSA, SID, ACS, IEEE, and Chinese Vacuum Society, and has served as the reviewer for many peer-reviewed journals and TPC member for several academic conferences.

About the author

Lei Sun is currently an associate professor at Fuzhou University and a council member of the Fujian Physics Association. She received her Ph.D. from Fuzhou University, China in 2019. As a research scholar, she visited the Hong Kong University of Science and Technology and the Institute of Material Structure of the Chinese Academy of Sciences. Her main research field is information optoelectronic display technology, especially in field emission display and quantum dot luminescence. So far, she has received multiple grants from the National Natural Science Foundation of China and the Local Natural Science Foundation.

She has published more than 20 papers in academic journals, and has a number of authorized Chinese invention patents. In 2015, she was selected as the Outstanding Young Scientific Research Talents Program of Fujian Universities, and in 2018 she was selected as the New Century Excellent Talents Program of Fujian Universities.

About the author

Tailiang Guo received his MS degree in applied physics from Fuzhou University of China in 1986. He has published more than 200 papers on display technologies. His research interests focus on FED materials and devices, 3-D display, printing electronics, and its applications.

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Reference

Sun, L., Chen, E., & Guo, T. (2020). Field emission enhancement of composite structure of ZnO quantum dots and CuO nanowires by Al2O3 transition layer optimizationCeramics International, 46(10), 15565-15571.

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