Zno nanorods Grown on Si Substrate by Ultrasonic Spray Pyrolysis

ZnO Nanorods Grown on Si Substrate by Ultrasonic Spray Pyrolysis
M. Rokhimova, Kh. Murodova, M. Mamatkarimova, M. Egamberdieva, D. Sagidov
Department of Physics, National University of Uzbekistan named after Mirzo Ulugbek, Tashkent, 100714, Uzbekistan, [e-mail]

ZnO nanorods are promising nanostructures because of the large surface area, high aspect ratio, and unique shape. A large surface area is important for high-sensitivity sensors for gas detection. The high aspect ratio of ZnO nanorods allow excellent field emission for a high-efficiency electron source. ZnO nanorods provide possibilities for valuable applications such as light emitting diodes (LEDs) and solar cells owing to their structural advantages over thin films [1,2].

Ultrasonic spray pyrolysis is a method in which a nanostructure is deposited by spraying a solution with an ultrasonic nebulizer on to a heated surface. In comparison with the conventional methods, the ultrasonic spray pyrolysis method provides advantages such as low equipment cost, good thickness uniformity over a large area, low temperature and low vacuum requirement in processing [3].
In this work, we report the growth of ZnO nanorods by using the ultrasonic spray pyrolysis with catalyst-free condition on Si substrate. In order to prepare ZnO nanorods, we used zinc acetate as the zinc source. The distilled water was used as a solvent and air as a carrier gas and oxygen source. The Si wafer was used as a substrate for the growth of nanorods. First, the ZnO thin film was deposited on Si substrate to make a seed layer. The Si substrate temperature was set at 450 ⁰C, and the thickness of ZnO film was about 200 nm. Then ZnO nanorods were deposited at 600 ⁰C on that seed layer. The morphology and structure of nanorod arrays were studied by scanning electron microscope (SEM).
Figure 1 shows the SEM images: (a) top view and (b) cross section of ZnO nanorods grown on Si substrate covered with a ZnO seed layer. It shows that vertically aligned ZnO nanorods were grown on seeding-layer patterns whereas the nanorods were hardly grown on the bare silicon parts using the same condition. The average diameter and the length of ZnO nanorods were 95 nm and 1.2 µm, respectively.
(a) (b)

Fig. 1. SEM images: (a) top view and (b) cross section of ZnO nanorods grown on Si substrate covered with a ZnO seed layer.
Figure 2 shows the photoluminescence (PL) spectra of (a) ZnO film and (b) ZnO nanorods measured at room temperature, respectively. It is seen from Fig. 2 that the PL spectrum of ZnO nanorods shows only one peak at 3.25 eV related to the recombination of free excitons and there is not observed another PL peak at 2.7 eV which is connected with the deep level defects. This demonstrates more high quality of ZnO nanorods comparing with ZnO films grown by USP.

Fig. 2. PL spectra of (a) ZnO film, (b) ZnO nanorods measured at T = 300K.


References
[1] F. Yang, M. Shtein, S.R. Forrest, Nature Mater. 4, 37 (2005).
[2] Y.Y. Lin, C.W. Chen, J. Chang, T.Y. Lin, I.S. Liu, and W.F. Su, Nanotechnology, 17, 1260 (2006).
[3] S. R. Ardekania, et al., Journal of Analytical and Applied Pyrolysis, 141, 104631 (2019).


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Rokhimova Mokhira Kenjaboy qizi

Magistr
yo‘q
O‘z M U Fizika fakulteti “Qayta tiklanuvchi energiya manbalari va atrof muhit fizikasi ” yo‘nalishi I- kurs magistranti
Manzil: Toshkent shahri,Talabalar shaharchasi,Unversitet ko‘chasi 4-uy, Mirzo Ulug‘bek nomidagi O‘zbekiston Milliy Unversiteti Fizika fakulteti, “Yarimo’tkazichlar va polimerlar fizikasi” kafedrasi,2-qavat,240-xona,
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ZnO Nanorods Grown on Si Substrate by Ultrasonic Spray Pyrolysis
Yarimo‘tkazgichlar va polimerlar fizikasi, nanotexnologiya