# Creation of One- and Two-Dimensional Copper and Zinc Oxides Semiconductor Structures
## 2 Formation of One- and Two-Dimensional ZnO and CuO Structures
In [116], it was shown that the quality of PLD thin films deposited by the PLD method is influenced by the substrate temperature. Figure 6 illustrates that at temperatures up to 100 \({}^{\circ}\)C, the substrates appear to be covered with clusters of nanoparticles forming a dense film. Beginning from a certain temperature, the porous structure will initially consist of small grains, which will favor the growth of small particles, limiting the preferential growth in certain directions and affecting the crystallinity of ZnO thin films [116]. It should be noted that laser-based methods offer advantages in terms of control over size, shape, and crystal structure, making them valuable for the fabrication of various nanostructures for research and applications Nevertheless, several challenges and difficulties take place in the synthesis of one-dimensional and two-dimensional ZnO and CuO structures using laser-based or laser-assisted methods. One of these challenges is the need to optimize  
Figure 5: SEM image of the hybrid material containing ZnO nanosheets and one-dimensional carbon nanotubes (CNT) obtained by pulsed laser ablation over a period of 10 min, at a laser wavelength of 532 nm [106]. laser irradiation parameters, such as power, frequency, and pulse duration, to achieve the desired structural characteristics. Additionally, thermal effects and thermal stresses induced by laser irradiation can also negatively impact the quality of the synthesized structures, making monitoring and control of these aspects a critical part of the process. The distribution of power density within the laser spot can indeed influence the quality of the synthesized structures when using laser-based methods. This is an important factor that affects the growth, morphology, and properties of nanomaterials. Thus, in [117], a method of pulsed laser synthesis in which CO\({}_{2}\) laser irradiation is used for ablating the zinc acetylacetonate in water and alcohol solvents was described. The mechanism of the formation of ZnO nanorods and nanowires involves the aggregation of small particles with the formation of larger solid particles in the form of one-dimensional structures in the process of self-assembly. The length and width of the formed one-dimensional structures depend not only on the irradiation time but also on its intensity. It has been shown that ZnO nanoparticles are formed not only in the peripheral regions of the laser spot characterized by lower power density but also near the irradiation site. However, these nanoparticles do not aggregate into larger ones [117]. Laser-induced chemical deposition was realized in [118], where the ZnO nanowires grew on the deposited nanoparticles, and the area of zinc oxide deposition on the silicon wafer was limited directly by the laser beam. It has been noted that intense laser irradiation can stimulate the nucleation of ZnO, but it may also result in an excessive presence of hydroxide ions and the delocalization of the deposition. In [119], a laser-induced hydrothermal growth (LIHG) process was carried out using a continuous wave diode laser with a profile beam shaper for uniform irradiation over the entire surface area. The settings of laser power distribution, beam velocity, and exposure time allowed for the precise control of the morphology of the produced quasi-one-dimensional ZnO nanostructures. Uniform power density distribution can contribute to the formation of structures with smoother and more homogeneous surfaces, which is crucial for certain applications. A non-uniform  
Figure 6: SEM images depicting ZnO thin films deposited at different temperatures: RT is Room Temperature [116]. distribution, however, may lead to heterogeneity in sizes and shapes within the synthesized nanomaterials. At that, the value of laser power density can influence the crystal structure of the resulting nanomaterials, i.e., may promote the growth of crystals with specific orientations or phases, and at high power densities, the structures may be damaged [120].