Fabrication of A III B V nanostructures by droplet epitaxy has many advantages over other epitaxial techniques. Although various characteristics of the growth by droplet epitaxy have been thoroughly studied for both lattice-matched and mismatched systems, little is known about physical processes hindering the formation of small size InAs/GaAs nanostructure arrays with low density and thin wetting layer. In this paper, we experimentally demonstrate that the indium droplet diameter can be reduced by decreasing the deposition time, but this reduction is limited by a critical thickness of droplet formation dependent on the substrate temperature. Using the kinetic Monte Carlo model, we propose a mechanism considering that the droplet formation begins when the system overcomes a barrier determined by the substrate attraction. As a result of physical and chemical balancing between adatom aggregation and substrate wetting, this attraction becomes weaker with increasing either temperature or deposition amount, which leads to the critical layer formation and subsequent nucleation. Using this mechanism, it is possible to provide a wide control over the nanostructure growth which is especially important at high temperatures when the processes of the island ripening are particularly intensive.

Three-dimensional orientation of the ferroelectric (FE) domain structure of a BiFeO3 epitaxial film was investigated by scanning electron microscopy (SEM) using back-scattered electrons and piezoresponse-force microscopy (PFM). By changing the crystallographic orientation of the sample and the electron collection angle relative to the detector, we establish a link between the orientation of polarization vectors (out-of-plane and in-plane) in BiFeO3 film and the backscattered electron image contrast in agreement with PFM investigations. The different FE polarization states in the domains correspond to altered crystalline environments for the impingent primary beam electrons. We postulate that the resultant back-scattered electron domain contrast arises as the result of either differential absorption (through a channelling effect) or through back-diffraction from the sample which leads to a projected diffraction pattern superposed with the diffuse conventional back-scattered electron intensity. We demonstrate that SEM can be sensitive for both out-of-plane and in-plane polarization directions using BSE detection mode and can be used as a non-destructive and fast method to determine 3D FE polarization orientation of domains.

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Electrochemical anodization is a powerful method for the preparation of oxide thin films with controlled thickness, structure, and composition and proves as a promising approach to be applied to memristive devices. Here, experimental studies on titanium oxide nanoscale structures produced by local anodic oxidation and the influence of the thickness on the memristive properties are presented. Controllable preparation of forming‐free memristive cells with switching voltages less than 3 V are demonstrated. The chemical composition and oxidation state of the elements in the TiOx nanostructures are analyzed by means of X‐ray photoelectron spectroscopy, which reveals the formation of TiO2 (458.4 eV), Ti2O3 (456.6 eV), and TiO (454.8 eV). The increasing thickness of the devices from 4.5 ± 0.7 to 7.9 ± 0.3 nm leads to a decrease in the OFF to ON resistance ratio from 250 to 10.7, respectively. The mechanism of formation and resistive switching in the anodic devices is also discussed. The results can be applied to the design and development of technological processes for memristive structure manufacturing based on electrochemical oxidation.

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