The Fabrication of the Zernike Electrostatic Phase Plate and its application on the Phase TEM

• Main Authors: Wang, Wan-Jhih, 王婉稚
• Other Authors: Fu-Rong Chen
• Format: Others
• Language: en_US
• Published: 2007
• Online Access: http://ndltd.ncl.edu.tw/handle/33536626570776722812

碩士 === 國立清華大學 === 工程與系統科學系 === 95 === Abstract Transmission Electron Microscopy (TEM) is a powerful tool to analyze the inner structure of the specimen. However, for the biological samples which mainly compose of low atomic number elements such as C, N and O or for the doping layer a the semiconductor which has doped elements of atomic numbers close to the matrix, the contrast of the image is too poor to analyze precisely. The contrast of TEM images come from the intensity of the electron beams and the phase difference between the direct and scattered electron wave. The Zernike Electrostatic Phase Plate (ZEPP) is a novel device in TEM altering the phase shift between the direct electron wave and the scattered electron wave to obtain Zernike phase contrast. The Zernike phase contrast is the most effective way to increase the image contrast without loss of resolution. The main structure of a ZEPP is a 5-layer ring shape structure—3 layers of electrode and 2 dielectric layers between each electrode. A voltage is applied to the middle electrode and the top and bottom electrodes are grounded. In this way an electrostatic field is constructed in the inner cylinder of the phase plate ring structure and is effective as an electrostatic lens. As the direct electron wave passes through the electrostatic field, its phase is shifted. The ZEPP is fabricated by Micro-Electro Mechanical System (MEMs) techniques for it is able to handle the micro-meter scale dimension design of the phase plate.