This talk will consist of two parts, each dedicated to functional characterization of nano-micro structures, such as GaAs nanowires (NWs) and Si micropillars (MPs). These methods address the requirements for characterizing nanostructures with high aspect ratio (HAR) and large array, thus tend to be a standard characterization in NW based devices. The first part focuses on a characterization of GaAs NW based solar cell structures by means of conductive-probe atomic force microscopy (C-AFM). Using this method, we explain how non-uniformity in electrical properties of NW p-n junctions in array can be quantified by different regimes in C-AFM, such as current scanning or single NW IV characterization. Also, we show that the small fraction of low performing NWs cannot determine the overall performance, but non-sensitive to light NWs can act as a leakage paths and drastically reduce the photovoltaic properties of the device. In the second part we introduce electrochemical impedance spectroscopy (EIS) for a characterization of the interfaces in oxide-semiconductor nanostructures. Surface passivation by ALD oxide is one of the option to suppress enhanced surface recombination in nano/micro structures due to high surface area. Despite complications with passivation step itself, analysis of the effect on interface defects requires advanced characterization. Standard capacitance-voltage (C-V) measurements require completion of the studied structure with metal gate. In HAR nano/micro structures metallization of the surface leads to discontinuity of the layer and difficulties with the area determination. By providing liquid electrolyte conformal contact, we have access to the full surface area of the HAR nanostructures thus able to quantify surface passivation by oxide layer. As an example of the characterization, we provide an analysis of the Al2O3 passivation of Si MPs, where we found the benefit of the low-temperature controllable thermal oxidation of Si MPs just before the ALD process.​ ​

515 room​​ (Birzhevaya line, 14​)