Investigations of a Statistical and Analytical Method to Find the Relationship between the Morphological and Optical...

In this study, a sapphire substrate with a patterned concave structure was used to prepare ZnO film/A-B glue, and the ZnO film/A-B glue with a patterned convex matrix was transferred onto a silicon wafer using the lift-off technology as the seed layer. Then, the hydrothermal method with different Zn(CH₃COO)₂ and C₆H₁₂N₄ concentrations as precursors was used to synthesize ZnO nanoflower arrays on the patterned convex ZnO seed layer. XRD pattern, FESEM, FIB, and photoluminescence (PL) spectrometry were employed to observe and analyze the properties of the synthesized ZnO nanoflower arrays. When Zn(CH₃COO)₂ and C₆H₁₂N₄ concentrations were 0.01, 0.02, 0.03, and 0.04 M, the average heights of the ZnO nanorods in the ZnO nanoflower arrays were 993, 1500, 1550, and 1650 nm, the average diameters of the ZnO nanorods were 50, 90, 105, and 225 nm, and the aspect ratios (H/D) of the ZnO nanorods were 19.9, 16.7, 14.8, and 7.33, respectively. A simple statistical and analytical method was investigated to estimate the densities (number of nanorods) of the ZnO nanoflower arrays in one 1 μm × 1 μm area. The total surface area (S) of the ZnO nanoflower arrays first increased from 5.05 × 10⁶ and then reached a maximum value of 1.20 × 10⁷ nm² as Zn(CH₃COO)₂ and C₆H₁₂N₄ concentrations increased from 0.01 to 0.02 M. For the systhesized ZnO nanoflower arrays, as the Zn(CH₃COO)₂ and C₆H₁₂N₄ concentrations increased from 0.01 to 0.04 M, their total volume (V) increased from the 6.23 × 10⁷ to 5.90 × 10⁸ nm³ and the S/V ratio decreased from 8.10 × 10^-2 to 1.84 × 10^-2. We found that ZnO nanoflower arrays with Zn(CH₃COO)₂ and C₆H₁₂N₄ concentrations of 0.2 M presented the maximum PL emission intensities. The calculated S/V ratios and X-ray photoelectron spectroscopy analyses are used to discuss the reasons for these results.