Filters

2020 - 20212

More filters

20222
Reset filters

Settings

DDC: 500 × Subject: Scanning electron microscopy ×

Search Results

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    Conversion of p–n conduction type by spinodal decomposition in Zn-Sb-Bi phase-change alloys
    ([London] : Macmillan Publishers Limited, part of Springer Nature Tokyo, 2020) Wang, Guoxiang; Shi, Haizhou; Lotnyk, Andriy; Shi, Daotian; Wang, Rongping
    Phase-change films with multiple resistance levels are promising for increasing the storage density in phase-change memory technology. Diffusion-dominated Zn2Sb3 films undergo transitions across three states, from high through intermediate to low resistance, upon annealing. The properties of the Zn2Sb3 material can be further optimized by doping with Bi. Based on scanning transmission electron microscopy combined with electrical transport measurements, at a particular Bi concentration, the conduction of Zn-Sb-Bi compounds changes from p- to n-type, originating from spinodal decomposition. Simultaneously, the change in the temperature coefficient of resistivity shows a metal-to-insulator transition. Further analysis of microstructure characteristics reveals that the distribution of the Bi-Sb phase may be the origin of the driving force for the p–n conduction and metal-to-insulator transitions and therefore may provide us with another way to improve multilevel data storage. Moreover, the Bi doping promotes the thermoelectric properties of the studied alloys, leading to higher values of the power factor compared to known reported structures. The present study sheds valuable light on the spinodal decomposition process caused by Bi doping, which can also occur in a wide variety of chalcogenide-based phase-change materials. In addition, the study provides a new strategy for realizing novel p–n heterostructures for multilevel data storage and thermoelectric applications.
  • Thumbnail Image
    Item
    High temporal-resolution scanning transmission electron microscopy using sparse-serpentine scan pathways
    ([London] : Macmillan Publishers Limited, part of Springer Nature, 2021) Ortega, Eduardo; Nicholls, Daniel; Browning, Nigel D.; de Jonge, Niels
    Scanning transmission electron microscopy (STEM) provides structural analysis with sub-angstrom resolution. But the pixel-by-pixel scanning process is a limiting factor in acquiring high-speed data. Different strategies have been implemented to increase scanning speeds while at the same time minimizing beam damage via optimizing the scanning strategy. Here, we achieve the highest possible scanning speed by eliminating the image acquisition dead time induced by the beam flyback time combined with reducing the amount of scanning pixels via sparse imaging. A calibration procedure was developed to compensate for the hysteresis of the magnetic scan coils. A combination of sparse and serpentine scanning routines was tested for a crystalline thin film, gold nanoparticles, and in an in-situ liquid phase STEM experiment. Frame rates of 92, 23 and 5.8 s-1 were achieved for images of a width of 128, 256, and 512 pixels, respectively. The methods described here can be applied to single-particle tracking and analysis of radiation sensitive materials.