Electric radiation mapping of silver/zinc oxide nanoantennas by using electron holography

Abstract

In this work, we report the fabrication of self-assembled zinc oxide nanorods grown on pentagonal faces of silver nanowires by using microwaves irradiation. The nanostructures resemble a hierarchal nanoantenna and were used to study the far and near field electrical metal-semiconductor behavior from the electrical radiation pattern resulting from the phase map reconstruction obtained using off-axis electron holography. As a comparison, we use electric numerical approximations methods for a finite number of ZnO nanorods on the Ag nanowires and show that the electric radiation intensities maps match closely the experimental results obtained with electron holography. The time evolution of the radiation pattern as generated from the nanostructure was recorded under radio frequency signal stimulation, in which the generated electrical source amplitude and frequency were varied from 0 to 5 V and from 1 to 10 MHz, respectively. The phase maps obtained from electron holography show the change in the distribution of the electric radiation pattern for individual nanoantennas. The mapping of this electrical behavior is of the utmost importance to gain a complete understanding for the metal-semiconductor (Ag/ZnO) heterojunction that will help to show the mechanism through which these receiving/transmitting structures behave at nanoscale level.

Precession Electron Diffraction and Orientation Phase Mapping of Assembled Ag/ZnO Nanoantennas

“…For completeness, grazing angle x-ray diffraction measurements on prepared substrates Ag/ZnO systems shown well-defined peaks associated to the main phases of ZnO nanorods and Ag nanowires respectively. A full understanding of the fit faces mechanism between Ag/ZnO along the mismatch direction undoubtedly will allow elucidating the mechanism through which the contact metal-semiconductor behaves at the heterojunction interface.The figure 1A shows Ag/ZnO metal-semiconductor systems grown by microwave irradiation process as described by Sanchez et al [2]. Two main features could be listed in the micrograph; first a constant distribution of ZnO nanorods covering completely the surface area along the silver nanowire and secondly the multi-pentagonal arrangement of ZnO nanorods running through the long axis of the silver nanowire.…”

“…The figure 1A shows Ag/ZnO metal-semiconductor systems grown by microwave irradiation process as described by Sanchez et al [2]. Two main features could be listed in the micrograph; first a constant distribution of ZnO nanorods covering completely the surface area along the silver nanowire and secondly the multi-pentagonal arrangement of ZnO nanorods running through the long axis of the silver nanowire.…”

Structural analysis of the epitaxial interface Ag/ZnO in hierarchical nanoantennas

“…This is done by controlling parameters such as the deposition rate, temperature, and concentration of the species. 5,6 Furthermore, perfectly aligned nanostructures can be monitored in real time within a transmission electron microscope as demonstrated in a previous work. 5 Recently, microwave irradiation processes (MIPs) have been employed as an alternative in the chemical synthesis of metallic nanoparticles, quantum dots, and assembled nanostructures.…”

“…5,6 Furthermore, perfectly aligned nanostructures can be monitored in real time within a transmission electron microscope as demonstrated in a previous work. 5 Recently, microwave irradiation processes (MIPs) have been employed as an alternative in the chemical synthesis of metallic nanoparticles, quantum dots, and assembled nanostructures. [7][8][9] The chemical synthesis using MIP reduces the reaction time and can produce a controlled growth with a good alignment of the crystalline nanostructures.…”

“…The density of ZnO NRs distributed along the Ag NWs as well as their length has been controlled by changing the three main variables in the chemical process: temperature, power, and reaction time as we reported in detail previously. 5 In order to understand the mechanism through which the ZnO NRs are coupled to the active faces planes (001) of the Ag NWs, a series of different reaction times were monitored by SEM. Figure 1 shows that the distribution of the ZnO NRs increases as a function of the reaction time.…”