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Low temperature solution growth is an attractive method for the preparation of nanostructured semiconductor materials with a wide range of applications from optoelectronics to chemical sensing. Despite the widespread application of low temperature solution growth, basic phenomena taking place during the growth are still under debate. The growth is mostly carried out in batch reactors, which are largely scalable and convenient for applied research and industrial applications. The batch reactors are filled with reactants and sealed, and there is no further inflow of the reactants during the growth. As the growth proceeds, the reactants are depleted, and the growth velocities decrease. Conventionally, the growth process is analyzed in static conditions, where the gradual depletion of the reactants in time is neglected. We analyzed time evolution of the growth of ZnO nanorod arrays on conventional sol–gel seed layers and on GaN substrates patterned by focused ion beam lithography. The focused ion beam lithography allows for precise control of the distances between the nanorods in the arrays. We show that for short growth times the growth is reaction limited, while for longer times the growth regime depends on the distance between the nanorods and changes from reaction limited to diffusion limited as the distance between the nanorods decreases. Under diffusion limited growth conditions, the nanorod height depends on the position within the pattern. The nanorods at the edge of the hexagonal pattern with 19 nanorods in diameter are significantly taller than the nanorods in the center. These experimental observations are validated by the solution of the diffusion equation by a finite element method.

One dimensional ZnO nanostructures prepared by favorable and simple solution growth methods are at the forefront of this research. Vertically oriented ZnO nanorods with uniform physical properties require high-quality seed layers with a narrow size distribution of the crystallites, strong c-axis orientation, and low surface roughness and porosity. It has been shown that high quality seed layers can be prepared by the sol–gel process. The sol–gel process involves three essential steps: preparation of the sol, its deposition by dip coating, and thermal treatment comprising preheating and annealing. We put emphasis on the investigation of the heat treatment on the properties of the seed layers and on the vertical alignment of the nanorods. It was demonstrated that for the vertical alignment of the nanorods, the preheating step is crucial and that the temperatures reported in the literature have been too low. With higher preheating temperatures, conditions for the vertical alignment of the nanorods were achieved in both investigated annealing atmospheres in air and in argon.

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The influence of polar and nonpolar crystallographic orientations of ZnO substrates on the current transport mechanism in poly(3,4‐ethylenedioxythiophene) poly(4‐styrenesulfonate) (PEDOT:PSS)/ZnO heterojunctions is investigated by DC and AC electrical measurements. It is shown that PEDOT:PSS forms high‐quality rectifying junctions on nonpolar planes of n‐type ZnO substrates, whereas on polar c‐planes, the quality of the junction is affected by the surface polarity, with lower‐quality junctions formed on the O‐polar c‐plane. The lower quality of the junction is attributed to partial degradation of the O‐polar surface caused by the acidic nature of PEDOT:PSS. By the analysis of current–voltage characteristics, it is demonstrated that the recombination‐tunneling mechanism dominates charge transport in the forward direction. An equivalent circuit is proposed to interpret the data obtained by impedance spectroscopy and the parameters of the equivalent circuit are extracted.