Direct nanomechanical machining of gold nanowires using a nanoindenter and an atomic force microscope

Abstract

Nanomechanical characterization of gold nanowires with a height of 160 nm, width of 350 nm and length of 5 µm has been carried out. Hardness and elastic modulus of the unreleased wires were measured by nanoindentation techniques using a nanoindenter. Post-fabrication mechanical machining of the gold nanowires is demonstrated. An array of nanoscale indents was successfully made on the gold nanowires. Nanochannels, nanoslots and complex nanopatterns were fabricated on a single gold nanowire by directly scratching/sliding the wire surface with the atomic force microscope (AFM) tip. Bending tests were performed to generate nanogaps on the wires using the nanoindenter. Direct machining techniques using a nanoindenter and an AFM should find more applications in the integration and manufacturing of micro/nanodevices.

Elastic properties of nanowires

“…8,10 Bending of nanowires 8,11,27,28 and stretching of nanocoils 29 have been reported in the literature but there is no report about the twisting nanowire experiments. Nakatani and Kitagawa 30 recently presented an atomistic study of twisting a nanowire using molecular dynamics.…”

“…Scanning transmission microscopy (STM), atomic force microscopy (AFM) and transmission electron microscopy (TEM) have been used to manipulate and characterize the properties of individual nanostructures. 8,9,10,11 In this paper, we present a model for the study of the elastic properties of amorphous straight nanowires. We propose an experimental setup that can be used to measure the Young's modulus and the Poisson's ratio of the composite material of an amorphous nanowire in two situations.…”

Molecular Dynamics Simulation Model of AFM-Based NanoMachining

“…It also has the ability to perform in situ repair/re-manufacturing of the position, size, shape, and orientation of single nanostructures. Some applications of AFM-based nanomachining include fabrication of micro-/nano-devices, individualized biomedicine and drug delivery, molecular reading and sorting, ultrahigh density memory, nanoscale circuitry, and fabrication of metal nanowires [3][4][5][6][7][8][9][10][11][12][13].…”

Can Young’s modulus and hardness of wire structural materials be directly measured using nanoindentation?

“…In recent studies, nanoindentation experiments combined with the Oliver and Pharr method (OP method) are frequently used to study the mechanical properties of 1D structural materials, especially properties of the 1D nanostructural materials (nanowires and nanobelts), because their mechanical properties are obtained with difficulty using the conventional testing instruments and techniques for their tiny volumes, sample clamping requirement, and super measuring precision. [1][2][3][4][5][6] A significant reduction in the measured Young's moduli of the aluminum borate (Al 4 B 2 O 9 and Al 18 B 4 O 3 ) nanowires, in the range of 50 to 70%, compared with those of the bulk materials was reported using nanoindentation with the OP method, which was then attributed to the loss of constraints on surface atoms. 4 The low Young's modulus, compared with the counterpart bulk materials, was also observed in other nanowires, such as ZnO, ZnS, and GaN.…”

“…1,7,8 In contrast, nanoindentation of gold and silver nanowires yielded the Young's moduli comparable with those of the bulk materials. 2,3 However, according to atomic simulations, the nanowires have a comparable Young's modulus with that of the corresponding bulk material, and the surface and edge effects of nanowires can be negligible when the diameters of the nanowires are larger than 3 to 4 nm. 9 Meanwhile, using the surface stress theory, the divergences between the Young's modulus of ZnO nanowires and those of the bulk materials are small (in the range of 10%) and decrease as the diameter increases, when their diameters are larger than 50 nm.…”