【作者】 赵彦桥；

【导师】 刘彩池；

【作者基本信息】 河北工业大学 ， 材料物理与化学， 2007， 硕士

【摘要】 GaAs是发展最快的第二代化合物半导体材料,具有迁移率高、直接跃迁型能带结构等优点,适合制造高频、高速器件和电路。作为基础半导体材料的半绝缘砷化镓(SI-GaAs)市场需求很大,其相关电子器件已发展到光通讯、卫星通讯、网络技术等诸多领域。器件和市场的需要对GaAs单晶材料提出了越来越高的要求,要求它在增大单晶直径的同时,还要减少晶体中的缺陷,不断提高各项物理参数及其均匀性等。因此对大直径SI-GaAs中的缺陷研究至关重要。本文主要采用标准配比的AB腐蚀液和熔融KOH腐蚀液对6英寸SI-GaAs晶片进行化学腐蚀,利用金相显微镜、扫描电镜和原子力显微镜来显示和检测缺陷的形貌、分布、密度等方面的情况,发现了不同形貌的位错和微缺陷。并利用PL Mapping技术,检测了样品的均匀性,得到了样品中缺陷的整体分布状况,研究了缺陷的微观特性和形成机理。实验结果表明,大直径SI-GaAs晶片,经化学腐蚀后表面出现了明显的位错胞状结构和网状结构,随着腐蚀时间的延长还会出现环状位错和枣核形层错结构等特殊缺陷形貌;SI-GaAs中的位错和微缺陷是紧密联系并且相互作用的;沿样品的直径方向位错密度呈U型分布;SI-GaAs中各种缺陷形貌的形成与晶体的结晶学方向和晶体的生长工艺等因素有关。以上研究结果有助于材料和器件生产者了解晶体缺陷对于器件生产的影响,改进材料生产工艺,提高器件质量等。更多还原

【Abstract】 GaAs is a compound semiconductor which has the most rapid development in semiconductor materials. GaAs is used to fabricate the devices and circuits of high frequency and speed because of its high mobility ratio and direct transition energy band structure. SI-GaAs have expansive market demand .The correlation devices have been used to light communication and secondary planet communication and so on. Because the growth technology and quality improvement of single crystal influence the devices development, it is important that the single crystal diameter to get to be enlarged, the defects to be decreased for the the physical parameters and quality uniformity to be improved. So the detects investigation of large diameter SI-GaAs is very important.In this paper, the distribution and pattern and density of detects in 6-inch SI-GaAs were investigated by mean of chemical etching and microscopy observation, etc. The detects were displayed by mean of AB etching and molten KOH etching; Different patterns of dislocation and microdefect were found when the etched samples were checked and observed by metalloscope and scanning electron microscope and so on. The whole defects distribution of sample was studied using PL Mapping technique in detail, and the sample uniformity was checked. The microscopic characterization of detects and formation mechanics were investigated.The experimental results showed that there are cell structures, netted structures in the sample surface, and so on. By analyzing the etching morphology of dislocations and micro-defects, it is indicated that their relationship are close and they are interactional. Furthermore, with the etching time extending, the defects with other patterns were found, which belong to the particular defect structures, for example the circularity dislocations. The distribution of dislocation density is U shape along the direction of diameter; The formation of defects in large diameter SI-GaAs was discussed which have some contacts with crystallography orientation and sample grown technology. The conclusions is very useful for the producers of material and device understand the defects effect on the quality of devices and materials.更多还原