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Femtosecond laser ablation has found wide-ranging applications in the surface structuring of nanoelectronics and nanophotonics devices. Traditionally, the inspection of the fabricated three-dimensional (3D) morphology was performed using a scanning electron microscope or atomic force microscopy in an ex situ manner after processing was complete. To quickly monitor and efficiently optimize the quality of surface fabrication, we developed an in situ method to accurately reconstruct the 3D morphology of surface micro-structures. This method is based on a triangulation optical system that utilizes structured illumination. The approach offers a super-resolution capacity, making it a powerful and non-invasive tool for quick in situ monitoring of surface ablation structures. [ABSTRACT FROM AUTHOR]

Thin films of silver were deposited on nonalkali glass substrates at substrate temperatures ranging from room temperature (28 °C) to 150, 200, 300, 400, and 500 °C at discharge pressures of 0.40, 1.20, and 2.00 Pa using direct current magnetron sputtering. On the basis of the measured cross-sectional and surface morphologies, crystallographic structures, and film properties, I discuss the dependence of the film structure and properties on the substrate temperature. The x-ray diffraction measurements showed that the <111> orientation was preferred for all deposition conditions. Scanning electron microscope observations revealed a microstructure of convex-shaped fine grains for a substrate at room temperature, while laterally growing, mound-shaped grains with flat-topped surfaces appeared at substrate temperatures of 400 and 500 °C. Atomic force microscopy also showed an increase in the lateral size and height of the mound-shaped structures with increasing substrate temperature. The lateral grain size evaluated from the areal particle density obtained from atomic force microscopy increased significantly with increasing substrate temperature, reaching 600–800 nm at a substrate temperature of 500 °C. The film stress also changed from compressive to tensile with increasing substrate temperature. The relative density, defined as the ratio of the deposited amount-of-substance to the physical-thickness, decreased significantly with increasing substrate temperature and, at a substrate temperature of 500 °C, was approximately 0.6 times as large as that obtained for thin films deposited at room temperature. The high surface diffusivity of the Ag adatoms induces the growth of laterally growing, mound-shaped grains. Besides, the energy accumulated in the thin films during sputter deposition induces the void formation to increase the efficiency of energy release in the form of heat. [ABSTRACT FROM AUTHOR]

GaN nanowires are potential candidates for use in scanning probe microscopy due to their well-defined, reproducible, geometric shapes, their hardness, and their light guiding properties. We have developed and investigated probes for high resolution atomic force microscopy and scanning tunneling microscopy utilizing GaN nanowires as probes. The nanowires are n-doped and the morphology of the nanowires has been tailored for scanning probe microscopy by growing them with a sharp tip for measurements and high thickness for robustness. The individual GaN nanowires were removed from their growth substrate and attached onto commercial atomic force microscopy cantilevers or etched tungsten wires for scanning tunneling microscopy. A standard scanning electron microscope equipped with a nanoprobe, a focused ion beam column and a gas injection system was used to locate, transfer, and attach the nanowires. We evaluated the properties of the GaN probes on different substrates including HOPG, Au, SiO2, InAs, and GaAs. We demonstrate both atomic force microscopy and scanning tunneling microscopy measurements with single atomic layer resolution and evaluate the robustness of the tips by monitoring them before and after scanning. Finally, we explore the use of the tips for scanning tunneling spectroscopy demonstrating that reliable results, which can reveal information on the electronic properties of the surface-tip system, are obtainable. The fundamental properties of these probes, which are demonstrated in this work, show promise for future use of the probes in exploring semiconductor-semiconductor tunneling junctions at the nanoscale as well as for other scanning probe techniques where high resolution is required. [ABSTRACT FROM AUTHOR]

The spin Hall angle (SHA) represents the efficiency of the conversion between spin current into charge current and vice-versa. In this paper, we report the experimental detection of large enhancement of the effective SHA in heterostructures of yttrium iron garnet (YIG)/[Pt-Ag]/Pt and YIG/[Pt-Ag], when compared with measurements in YIG/Pt bilayers. The notation [Pt-Ag] represents the nanoparticles island formation of Ag in the Pt film. In order to investigate the role played by the metallic nanoparticles in the spin-to-charge conversion process, we carried out microwave spin pumping measurements in the following samples: YIG/Ag(3 nm)/Pt(6 nm), YIG/[Pt(3 nm)-Ag(3 nm)]/Pt(3 nm) and YIG/[Pt(6 nm)-Ag(3 nm)]. By means of high-resolution scanning electron microscope (HR-SEM) investigation, we confirmed that layers of Ag exhibit islands nanoparticle structures when grown on the surface of the Pt, which are characterized by the Volmer-Weber mode. The spin pumping results show that the Ag nanoparticles can enhance the charge current created by the inverse spin Hall effect (IISHE) up to three times larger than the single Pt layer. Also, by analyzing atomic force microscopy (AFM) images, obtained for samples with different thickness of the Ag layer, we conclude that the roughness plays an important role in the enhancement of the IISHE. Therefore, taking advantage of poor wetting properties of Ag over Pt layer, it was possible to create nanoscopic particles of Ag randomly grown in the Pt layer. The nanoparticles serve as nanoscopic molds to locally increase the SHA. This feature represents an improvement in searching more efficient methods of the spin-to-charge conversion and opens up the possibility of tuning the SHA by controlling the size and shape of the Ag nanoparticles. [ABSTRACT FROM AUTHOR]

More than 40 years after its invention, the atomic force microscopy (AFM) can be integrated with scanning electron microscope (SEM) instruments as an increasingly capable and productive characterization tool with sub-nanometer spatial resolution. The authors have designed and developed an AFM instrument capable to be integrated into any SEM or in a combination of SEM with a focused ion-beam (FIB) tool. The combination of two or more different types of techniques like SEM, energy dispersive x-ray spectroscopy, and AFM is called correlative microscopy because analytical information from the same place of the sample can be obtained and correlated. For the first time, they introduced to the SEM/FIB tool correlative nanofabrication methods like field-emission scanning probe lithography, tip-based electron beam induced deposition, and nanomachining. The combination of all these methods provides a completely new nanotechnology instrument, which should be seen as a tool for correlative nanofabrication and microscopy. Thus, it provides for the first time the capabilities of a stand-alone instrument with the capabilities of nondestructive three-dimensional tip-based metrology and nanofabrication into the combined SEM/FIB tool. In this article, the authors describe all these methods in detail and present a brief example of the results obtained. They demonstrate that the self-sensing, self-actuating cantilevers (called active cantilevers) equipped with Diamond tip are a versatile toolkit for fast imaging and emerging nanofabrication. The AFM integrated into SEM is using active cantilevers that can characterize and generate nanostructures all in situ without the need to break-vacuum or contaminate the sample. [ABSTRACT FROM AUTHOR]

With rapidly increasing numbers of studies of new and exotic material uses for perovskites and quasicrystals, these demand newer instrumentation and simulation developments to resolve the revealed complexities. One such set of observational mechanics at the nanoscale is presented here for somewhat simpler material systems. The expectation is that these approaches will assist those materials scientists and physicists needing to verify atomistic potentials appropriate to the nanomechanical understanding of increasingly complex solids. The five following segments from nine University, National and Industrial Laboratories both review and forecast where some of the important approaches will allow a confirming of how in situ mechanics and nanometric visualization might unravel complex phenomena. These address two-dimensional structures, temporal models for the nanoscale, atomistic and multiscale friction fundamentals, nanoparticle surfaces and interfaces and nanomechanical fracture measurements, all coupled to in situ observational techniques. Rapid future advances in the applicability of such materials science solutions appear guaranteed. [ABSTRACT FROM AUTHOR]

In low energy scanning electron microscope (SEM) with primary electron energy less than 1.0 keV, the dependence of SEM contrast on crystallographic orientation within a range of 1.0 nm in depth has been investigated by utilizing 4H-SiC (0001) as a standard sample having a definitive electron penetration depth marker layer at hexagonal sites. Reflecting the difference of the direction of topmost two Si-C bilayers stacking sequence (0.50 nm in depth), clear bright and dark SEM contrast has been observed by adjusting the sample tilting and rotation angles by a conventional Everhart-Thornley type in-chamber detector. It is revealed that the brighter signal emission arises when the incident primary electron beam direction is almost parallel to the topmost stacking sequence direction. This angular coincidence was verified separately by correlating low energy SEM contrast from 3C-SiC (111) of no hexagonal sites with its electron back scattered diffraction pattern for identifying stacking sequence direction. The obtained results suggest a potential of low energy electron to characterize the crystallographic orientation just beneath the surface without using any special detector. [ABSTRACT FROM AUTHOR]