Extraordinary transmission in ultraviolet band in (Al<sub><i>x</i></sub>Ga<sub>1–<i>x</i></sub>)<sub>2</sub>O<sub>3</sub>/Al nanopore array
Authors: Zhu Wen-Hui , Feng Lei , Zhang Ke-Xiong , Zhu Jun ,   School of Physical Science and Technology, Inner Mongolia University, Hohhot 010021, China,   School of Integrated Circuits, Dalian University of Technology, Dalian 116620, China
Published: September 2024

<sec>The finite difference time domain method is used to compute the transmissions of periodic triangular-lattice Al nanopore arrays on (Al<sub><i>x</i></sub>Ga<sub>1–<i>x</i></sub>)<sub>2</sub>O<sub>3</sub> thin film substrates. The influences of Al component <i>x</i> in(Al<sub><i>x</i></sub>Ga<sub>1–<i>x</i></sub>)<sub>2</sub>O<sub>3</sub> substrate, and the thickness, aperture and period of Al nanopore array on their optical transmission behaviors are studied systematically.</sec><sec>The numerical results indicate that when <i>x</i> = 0, there are two strong transmission peaks at 263 nm and 358 nm, respectively. As <i>x</i> increases, the transmission peak at 263 nm exhibits a slight blue-shift, with intensity first increasing and then decreasing. Meanwhile, the transmission peak at 358 nm demonstrates a noticeable blue-shift and its intensity strengthens continuously. The change of Al component <i>x</i> has a significant effect on the peak position of the transmission peak in the longer ultraviolet band and the peak transmission in the shorter ultraviolet band. If the periodic structure of the nanopore array keeps unchangeable, the two prominent transmission peaks appear near 244 nm and 347 nm, respectively, as the air column apertures enlarge. Remarkably, these dual peaks initially undergo a red-shift, followed by a blue-shift, while the transmission steadily increases and the reflectivity decreases. The change in aperture size can significantly affect the peak transmission, and by controlling the aperture size appropriately, the transmission intensity can be significantly enhanced. With the expansion of the period, the two strong transmission peaks are located at 249 nm and 336 nm, respectively, and the two transmission peaks show obvious red-shift. The former transmission peak is redshifted to 304 nm, and the latter one is redshifted to 417 nm. Moreover, the transmissions at these peaks continue to decrease. The change in period can significantly affect the central wavelength of the transmission peak, and the periodicity of the array plays a dominant role in modulating the peak position in a large wavelength range. As Al thickness increases, a blue-shift of the transmission peak occurs at 380 nm , and the transmission decreases continuously. The change in thickness significantly affects the transmission intensity of the transmission peak in the longer ultraviolet band and the visible light region, but it is not so pronounced as the effect of aperture size on transmission intensity.</sec><sec>Through reasonable design and optimization of structural parameters of Al nanopore array/(Al<sub><i>x</i></sub>Ga<sub>1–<i>x</i></sub>)<sub>2</sub>O<sub>3</sub>, the peak position of transmission peak can be effectively regulated and the extraordinary transmission in ultraviolet band can be achieved.</sec>