2024

01-07

扫描隧道显微镜针尖的制作方法概述(一)

The size, shape, and chemical identity of STM needle tips not only affect the resolution and shape of scanning tunneling microscope images, but also affect the measured electronic states. The commonly used STM tip materials include tungsten (W), nickel (Ni), platinum iridium (Pt Ir), silver (Ag), and gold (Au) [2]. Various STM tip preparation methods can be mainly divided into two categories: (I) mechanical and (II) physical and chemical. Mechanical preparation methods include shearing, metal processing, and breaking metal wires into fragments to obtain sharp needle tips. The needle tips prepared by these methods are often difficult to reproduce, with problems such as shape asymmetry or multiple needle tip arrangements. When scanning an uneven sample surface, it is difficult to obtain the correct surface morphology with these needle tips. When preparing needle tips using physical and chemical methods, clear shapes can be obtained by adjusting process parameters. The technologies used in this process include electrochemical corrosion, electrochemical polishing, ion milling, and electron beam deposition [3]. At present, tungsten needle tips, nickel needle tips, silver needle tips, and gold needle tips are commonly prepared by electrochemical corrosion method, while platinum iridium wire needle tips are commonly prepared by shear method. Spin polarized scanning tunneling microscopy is an emerging surface spin resolution technique, and one of the key steps in SP-STM experiments is to prepare magnetic needle tips that can generate spin polarized electrons. These can be prepared directly from magnetic materials or by coating magnetic thin films on non-magnetic needle tips.

2018

10-17

真空蒸发镀膜技术浅析(二)

Atomic Layer Deposition (ALD) was initially called Atomic Layer Epitaxy (ALE), also known as Atomic Layer Chemical Vapor Deposition. (AtomicLayerChemicalVaporDeposit, ALCVD). Atomic layer deposition is the continuous introduction of at least two gas-phase precursor species onto a substrate in a heated reactor. The chemical adsorption process automatically terminates when the surface is saturated, and the appropriate process temperature hinders the physical adsorption of molecules on the surface. one

2018

10-17

真空蒸发镀膜技术浅析(三)

The basic concept of vacuum in vacuum technology, "vacuum" generally refers to a gas state in a given space where the gas pressure is lower than one atmosphere, which means it is a relatively thin gas state compared to normal atmospheric pressure. Vacuum degree is an objective measure of the degree of gas thinness. According to the theory of vacuum technology, the degree of vacuum is usually expressed by the pressure of the gas. In the International System of Units, pressure is measured in pascals (Pa), with 1Pa=1N/m2. Other commonly used units include Torr, mmHg, mbar, and engineering atmospheric pressure (kg/mm

2018

10-12

真空蒸发镀膜技术浅析(一)

Part 2: Knife edge flange dimensions Vacuum technology Bakableflanges Part2: knife edge dimensions (ISO/TS3669-2:2007, IDT)

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