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Copper nanowires (Cu-NWs) are leading contenders to replace indium tin oxides (ITOs) based traditional transparent conducting electrodes from the market due to their high mechanical flexibility and low-cost. In this work, Kilo-electron-volt (KeV) hydrogen (H+) ions beam irradiation-induced reduction in diameters of Cu-NWs is examined through transmission electron microscope (TEM) and scanning electron microscope (SEM). The reduction in diameters of Cu-NWs is found to occur via H+ ions beam irradiation-induced collision cascade of atomic displacements mechanism lead to continual reorganizing Cu atoms in individual Cu-NWs lattices. Formation of defect clusters or loss of crystal structure is not found in x-ray diffraction (XRD) patterns due to H+ ions beam irradiation. These experimental findings may potentially be applied to enhance spaces between NWs in complex Cu-NWs meshes for application as transparent conducting electrodes. Moreover, this study has also significance in exploring the possibility for application of Cu-NWs meshes based optoelectronic devices in harsh environment containing plenty of H+ ions such as for use in spacecrafts for upper space missions.

In order to replace conventional transparent conducting electrodes, metal nanowires (MNWs) networks have long been act as promising contenders due to their high mechanical flexibility. However, nanowire-nanowire contact resistance is main technical obstruction in terms of improvement in their performance. To reduce nanowire-nanowire contact resistance, welding of nanowires (NWs) is essential. In this work, MeV proton and argon ions beam irradiation induced nanoscale welding technique to fabricate X-, Y-, II- and T-shaped molecular junctions between nickel nanowires (Ni-NWs) is presented. Ni-NWs are irradiated by 2.75 MeV proton ions and 3.5 MeV argon ions at doses 1x1016ions/cm2 and 5x1015 respectively while temperature is kept constant. Transmission electron microscopy (TEM), scanning electron microscopy (SEM) and x-ray diffraction (XRD) results reveal that Ni-NWs are welded without losing stability in crystal structures of NWs. Afterward, a two-dimensional large scale random network of Ni-NWs is fabricated by 3 MeV proton ions beam irradiation induced nanoscale welding of Ni-NWs at crossing positions. Proton ion beam induced large scale network fabrication is confirmed by TEM and SEM techniques. Moreover, these networks are characterized optically using UV-VIS spectroscopy. It is observed that at a beam fluence of 5x1015 ions/cm2, perfect molecular junctions between Ni-NWs in X-, II-, and V-shapes are achieved and a large scale welded network of Ni-NWs is obtained without distorting the morphology of NWs. Moreover, structure of Ni-NWs remains stable under 3MeV proton ions beam irradiation and networks are found to be optically transparent. The results exhibit that fabrication of Ni-NWs network precede through three steps: i- High energy ions beam irradiation induced heat spikes lead to locally heat and fuse Ni-NWs, ii- Formation of molecular junctions on small scale, iii- Formation of large scale network Ions beam irradiation induced welding of Ni-NWs can improve performance of NWs networks by reducing contact resistance between NWs for application as transparent conducting electrodes. These high quality welded MNWs networks may potentially be applied as transparent conducting electrodes in optoelectronic devices.

The effect of copper ions (Cu+) of various fluencies on optical and electrical properties of silver nanowires (Ag-NWs) thin films is investigated. It is found that electrical conductivity and optical transmittance rises with increase in fluencies of copper ions. At 3x1015 ions/cm2, optical transmittance of Ag-NWs thin films increased upto 80 % in the visible (Vis) region and 55% in ultraviolet (UV) region in comparison with pristine Ag-NWs thin films. At the same beam fluence of Cu+ ions, electrical conductivity is raised thrice to that of pristine value. The increase in optical transmittance is attributed to Cu+ ion beam irradiation-induced localize heating effect cause melting and slicing of Ag-NWs, whereas Cu+ ion beam induced fusion of Ag-NWs at contact points is the main reason to enhance electrical conductivity. This study offers a technical base for designing of transparent conducting electrodes (TCEs) based on Ag-NWs thin films for multiple photovoltaic applications. Besides, this investigation is also helpful for application of photovoltaic devices based on MNWs thin films in radiations containing environment such as upper space.

Metal nanowires (MNWs) are proven to be excellent innovative conducting materials for next generation of nanodevices either in form of transparent electrodes for solar cells or for interconnecting conducting nanowires to incorporate multiple nanodevices. To exploit exceptional properties of MNWs networks in future nanodevices, effective joining between various types of MNWs is critical. This study is based on joining of copper nanowires (Cu-NWs) and nickel nanowires (Ni-NWs) through argon (Ar+) ions beam irradiation. Scanning electron microscopy (SEM), x-ray diffraction (XRD) and transmission electron microscopy (TEM) results exposed that Ag-NWs are effectively connected to each other on intersecting positions and crystal structure also remained un-damaged. In addition, the results exhibit that Ar+ ions beam irradiation induced sputtering of atoms from NWs lattices lead to produce point defects and accumulation of these point defects on crossing sharp angle contact areas, eventually lead to connect these NWs. A basic perception is the exploitation of Ar+ ions beam irradiation induced nanowelding technique for construction of complex and random networks of well-connected multiple MNWs for application in future nanodevices or optoelectronic devices.

This report is based on study of defect clusters or amorphous matrices induced in nickel nanowires (Ni-NWs) due to interaction of a beam of ~ 60 KeV hydrogen (H+) ions. Ni-NWs are exposed to various fluencies of hydrogen (H+) ions ranging between ~ 1014 ions/cm2 to 1017 ions/cm2. The analysis of pristine and hydrogen (H+) ions irradiated Ni-NWs samples has been mainly done using scanning electron microscopy (SEM), transmission electron microscopy (TEM) and x-ray diffraction (XRD) techniques. SRIM (stopping range of ions in matter) simulation is performed to corroborate the production of defect clusters/amorphous matrices in Ni-NWs theoretically. Moreover, basic insight of defect creation in Ni-NWs due to interaction of low energy in kilo-electron-volt (KeV) range hydrogen (H+) ions has been built using collision cascade theory. The purpose of this analysis is to explore the possibility of application of Ni-NWs based future nanodevices in environment containing plenty of hydrogen (H+) ions such as for use in spacecrafts employed for upper space missions.

A random two-dimensional nano-network of silver nanowires (Ag-NWs) was fabricated by MeV Hydrogen (H+) ion beam irradiation. Ag-NWs were irradiated under H+ ion beam at different fluences at room temperature. Ag-NWs network was fabricated by H+ ion beam induced coalescence of Ag-NWs at the crossing and the parallel positions. H+ ion beam induced coalescence was confirmed by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Moreover, structure of Ag NWs remains stable under H+ ion beam. Threshold dose for the stability of Ag NWs structure under H+ ion beam irradiation was 5x1015 protons/cm2 at room temperature, confirmed by TEM, and XRD. Morphology also remains stable under H+ ion beam irradiation. No slicing, cutting of Ag-NWs were observed under MeV H+ ion beam irradiation. This observation is useful for using Ag-NWs based devices in upper space where protons are abandon in MeV to GeV energy ranges. The results exhibit that the formation of Ag-NWs network proceeds through three steps: ion beam induced local heating, formation of simple junctions, and the formation of large scale network. This high quality network will also be useful as a transparent electrode for optoelectronics devices.

Here, we demonstrate a MeV proton beam irradiation induced nanowelding technique to fabricate X-, Y-, T and II-shapes molecular junctions between Ag nanowires, both suspended and deposited on substrates. High-resolution transmission electron microscopy, X-ray diffraction and Scanning electron microscopy revealed that the nanoweldings are nearly perfect, with the same crystal orientation. We further discuss various experimental aspects of this method which may potentially be used for developing complicated networks of joined nanowires. The high quality of the welding is attributed to the nanoscale sample dimensions, oriented-attachment mechanisms and mechanically assisted fast surface-atom diffusion.