Lecture

SEM Basics: Imaging Parameters

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In course

MSE-636: Organic semiconductors

Description

This lecture covers the basics of scanning electron microscopy (SEM), focusing on imaging parameters such as exposure time optimization, resolution, contrast, illumination, and detector choice. It explains how SEM images are generated step by step through sequential scanning of the sample, controlled by scan coils. The lecture also discusses the impact of accelerating voltage on penetration depth and signal, the generation of different types of signals (SE, BSE, X-rays), and the challenges faced in SEM imaging, including beam damage, charging effects, and strategies to mitigate them.

Instructor

Frank Nüesch

Teaching & PhD PhD Students Elodie Didier, Ceren Mitmit, João Pedro Ferreira Assunção, Vahid Charkhesht Past EPFL PhD Students Hui Zhang, Simon Johannes Dünki, Yee Song Ko, Lei Wang, Sandra Christina Jenatsch, Nicolas Alexandre Serge Leclaire, Donatas Gesevicius, Surendra Babu Anantharaman, Markus Regnat, Philip Horst Caspari, Patrik Schürch, David Reber, Karen Verena Strassel, Sina Abdolhosseinzadeh, Matthias Diethelm, Francis Owusu, Camilla Arietta Vael-Garn, Yeerlan Adeli, Wei-Hsu Hu, Cansu Zeytun Kara

Official source

Related concepts (32)

Magnetic resonance imaging

Magnetic resonance imaging (MRI) is a medical imaging technique used in radiology to form pictures of the anatomy and the physiological processes of the body. MRI scanners use strong magnetic fields, magnetic field gradients, and radio waves to generate images of the organs in the body. MRI does not involve X-rays or the use of ionizing radiation, which distinguishes it from computed tomography (CT) and positron emission tomography (PET) scans.

Ion source

An ion source is a device that creates atomic and molecular ions. Ion sources are used to form ions for mass spectrometers, optical emission spectrometers, particle accelerators, ion implanters and ion engines. Electron ionization Electron ionization is widely used in mass spectrometry, particularly for organic molecules. The gas phase reaction producing electron ionization is M{} + e^- -> M^{+\bullet}{} + 2e^- where M is the atom or molecule being ionized, e^- is the electron, and M^{+\bullet} is the resulting ion.

Medical imaging

Medical imaging is the technique and process of imaging the interior of a body for clinical analysis and medical intervention, as well as visual representation of the function of some organs or tissues (physiology). Medical imaging seeks to reveal internal structures hidden by the skin and bones, as well as to diagnose and treat disease. Medical imaging also establishes a database of normal anatomy and physiology to make it possible to identify abnormalities.

Contrast agent

A contrast agent (or contrast medium) is a substance used to increase the contrast of structures or fluids within the body in medical imaging. Contrast agents absorb or alter external electromagnetism or ultrasound, which is different from radiopharmaceuticals, which emit radiation themselves. In x-ray imaging, contrast agents enhance the radiodensity in a target tissue or structure. In magnetic resonance imaging, contrast agents shorten (or in some instances increase) the relaxation times of nuclei within body tissues in order to alter the contrast in the image.

Scanning electron microscope

A scanning electron microscope (SEM) is a type of electron microscope that produces images of a sample by scanning the surface with a focused beam of electrons. The electrons interact with atoms in the sample, producing various signals that contain information about the surface topography and composition of the sample. The electron beam is scanned in a raster scan pattern, and the position of the beam is combined with the intensity of the detected signal to produce an image.

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