【作者】 史佳新；

【导师】 吉元；

【作者基本信息】 北京工业大学 ， 材料学， 2003， 硕士

【摘要】 本论文提出氧环境扫描电子显微分析方法，以减轻和补偿非导电氧化物类样品在电子束辐照作用下的表面充电现象。在常规扫描电子显微镜（SEM）中引入一定的氧气(样品室真空度仍维持在2×10-3( 4×10-2 Pa)，直接观察和分析非导电样品，而不需要在样品表面镀导电膜。同时不改变扫描电子显微镜原有的电子光学系统和探测系统。本工作搭建了扫描电子显微镜的氧气输送和控制装置。采用pA-电流表测量吸收电流信号，评价Al2O3、Cu/SiO2、用Y2O3稳定的ZrO2(YS-ZrO2)等氧化物表面的充电现象，以及氧环境的充电补偿作用。此外，通过样品加热和改变电镜的成像参数等方法，减轻非导电样品表面的充电效应。在10-3～10-2 Pa的氧环境中观察到Al2O3和Cu/SiO2样品表面的充电现象得到明显减轻。对YS-ZrO2样品加热到230℃，使其表面充电得到改善。本文讨论了在电子束辐照下，Al2O3、SiO2、YS-ZrO2等氧化物材料的充电机制，以及氧环境的充电补偿机制。电子束轰击造成表面电子受激解吸和电子束对内部缺陷的调制是充电的主要原因。对于样品表面电子受激解吸造成的充电可通过氧环境提供补偿,氧环境主要是通过及时补充氧空位、修复能带扭曲起作用的； 对于电子束调制内部缺陷造成的充电可通过加热试样减轻缺陷浓度来补偿。氧环境扫描电子显微分析是针对氧化物类非导电材料直接成像和分析的一种新颖而实用的方法。更多还原

【Abstract】 In order to reduce and compensate charge phenomena at the surface of non-conductive oxide materials under the electron irradiation, oxygen environmental scanning electron microscopy (SEM) is offered in this thesis. Introduce oxygen environment in general SEM (sample chamber in high vacuum of 2×10-3( 4×10-2 Pa), and directly observe and analyze materials (no conductive films), simultaneously, keep original electron optical and detecting system unchanged.In this work the devices of feeding and controlling oxygen are set up. Absorbable current is measured with a PA meter in order to estimate charge phenomena of non-conductive oxide materials (for example Al2O3、Cu/SiO2、YS-ZrO2 etc) and charge compensation in oxygen environmental SEM. Heating specimen and changing imaging parameter are performed to reduce charge phenomena. For Al2O3 and Cu/SiO2, a strong charge reduction is observed in oxygen environment of 10-3～10-2 Pa; Charge phenomena of YS-ZrO2 are reduced through heating to 230℃. The mechanisms of charge and charge compensation are discussed: We suggest electron stimulated desorption (ESD) at the surface and inner defects induced by the electron beam bombardment are main reasons of charge. The charge related to ESD can be compensated by oxygen environment, oxygen environment works mainly through making up oxygen vacancy and repairing energy band distortion in time. Heating the sample and reducing defect concentration can reduce the charge related to inner defects.Oxygen environmental scanning electron microscopy is a new and practical method for directly observing and analyzing non-conductive oxide materials.更多还原