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2Emission sources based on hydrothermal ZnO nanostructures
S.A. Kadinskava1'2*, V.M. Kondratev1,2, A.V. Nikolaeva1,2, E.S. Zavyalova1'2, D.S. Gets3, I.Kh. Akopyan4, A.Yu. Serov4, M.E. Labzovskaya4, S.V. Mikushev4, B.V. Novikov4,
I.V. Shtrom45, A.D. Bolshakov1,2,4,6
1- Center for Nanotechnologies, Alferov University, Khlopina 8/3, 194021 Saint Petersburg, Russia
2- Center for Photonics and 2D Materials, Moscow Institute of Physics and Technology, 9 Institutskiy Lane,
141701 Dolgoprudny, Russia
3- School of Physics and Engineering, ITMO University Lomonosov str 9, Saint Petersburg 191002, Russia
4- Faculty of Physics, St. Petersburg State University, Universitetskaya Embankment 13B, 199034
St. Petersburg, Russia
5- Institute for Analytical Instrumentation of the Russian Academy of Sciences, Rizhsky pr. 26, 190103
St. Petersburg, Russia
6- Laboratory of Advanced Functional Materials, Yerevan State University, Yerevan 0025, Armenia
Zinc oxide (ZnO) is one of the promising materials for development of UV emitters due to the band gap (3.37 eV at room temperature) and high exciton binding energy (60 meV) [1]. In addition, ZnO is inexpensive, relatively abundant, chemically stable, easily synthesized, and non-toxic. Although a wide variety of ZnO-based light-emitting devices (LEDs) have been developed so far, their performance, light-emitting ability, and production technology are still below expectations.
Hydrothermal synthesis is a method of growing various materials and compounds, based on the use of physical and chemical processes that take place in aqueous solutions at slightly elevated temperatures often used to obtain ZnO nanostructures [2].
In our work, Si (111) substrates are used for the hydrothermal synthesis of ZnO nanostructures since this material is known to be the most often used in nanoelectronics. Zinc acetate is used as a seed layer material. The growth solution consists of equimolar aqueous solutions of Zn(NO3)2 and hexamethylenetetramine (HMTA).
Two series of studies of the optical properties of zinc oxide were carried out using photoluminescence spectroscopy. The samples were placed in a closed-cycle helium cryostat (Janis Research Company, USA). The sample temperature was about 10 K. The PL was excited by a He-Cd laser (X = 325 nm, excitation power W = 50 kW-cm~2) and by an ultraviolet solid-state laser LCM-DTL-374QT (X = 355 nm). The excitation power of this laser was varied in the range from 1 to 800 kW-cm"2. The threshold generation value was 140 kW-cm-2. Laser generation is observed at different points of the sample, which indicates the good quality of the synthesized structures.
The synthesized ZnO was transferred from the growth substrate to a glass substrate and coated with perovskite CsPbBr3. Pumping was carried out at room temperature using a femtosecond laser (Light Conversion), pulse duration 150 fs, repetition rate 10 kHz, pump wavelength 480 nm. The threshold generation value was 70-120 ^J-cm-2. Laser generation is observed on single ZnO structures.
The results show that a simple hydrothermal synthesis method is promising for fabricate efficient light-emitting devices based on ZnO.
The presented study is supported by the Ministry of Science and Higher Education of the Rus-sian Federation (agreement 075-15-2024-671).
[1] U. Ozgur, Ya. I. Alivov, C. Liu, A. Teke, M.A. Reshchikov, S. Dogan, V. Avrutin, S-J Cho, H. Morkoj, A comprehensive review of ZnO materials and devices, Journal of Applied Physics, vol.98, pp. 041301, (2005).
[2] H.Y. Xu, H. Wang, Y.C. Zhang, W.L. He, M.K. Zhu, B. Wang, H. Yan, Hydrothermal synthesis of zinc oxide powders with controllable
morphology, Ceramics International, vol.30(1), pp. 93-97, (2004).
