【作者】 李彦菊；

【导师】 李克艳； 薛冬峰；

【作者基本信息】 大连理工大学 ， 功能材料化学与化工， 2011， 硕士

【摘要】 功能材料设计已经成为新材料领域的重要研究课题之一。材料设计的基础就是深刻认识晶体微观结构并建立物理性质与微观结构之间的定量关系。经过70多年的发展,电负性如今已经成为材料性质研究的基本参数之一,它表示分子中原子将电子吸引向自身的能力,所以由成键原子吸引电子能力决定的性质都与电负性存在一定的关系。带隙是决定半导体应用价值的主要特性参数之一,它表示电子从价带顶跃迁到导带底所需要的能量,它与成键原子对价电子的吸引力有关。实现对此参数的预测,可为新型半导体材料的开发提供指导。因此本论文从电负性观点出发来研究半导体材料的带隙。我们从材料的微观结构出发,研究带隙的本质决定因素。研究得出半导体带隙取决于两个因素：1)成键原子对电子的吸引能力；2)化学键上价电子的离域程度。从这两个角度出发,对ANB8-N型二元化合物半导体建立了电负性与带隙之间的定量关系。然后,将模型拓展到ABC2三元黄铜矿半导体带隙的计算。计算结果与实验符合的很好。半导体掺杂是带隙工程的一个重要技术手段,但是目前在掺杂合金半导体带隙的计算方面仍缺乏一种简单有效的方法。我们将模型推广到用于预测AχB1-χC和ABχC1-χ阴阳离子掺杂合金半导体的带隙。在计算过程中我们假定杂质离子进入主体化合物以后都是均匀分布并根据AC和BC的配位结构是否相同,将三元合金分为两类分别进行研究。计算值与实验值非常吻合。这说明电负性可以有效地用于材料带隙的预测。该模型表明可以通过分析材料的化学组成及晶体结构定量计算一些化合物和掺杂半导体材料的带隙,为材料带隙的预测以及半导体掺杂提供了有益的指导。更多还原

【Abstract】 Functional material design has already been one of the most important research objects. This bases on a sophisticated knowledge of crystal microscopic structure and the quantitative relationship between the structure and the physical properties of crystals. For more than 70 years, electronegativity has been a fundamental parameter for the study of material properties, which is defined as an attractive ability of the atom in molecule to the electrons. Therefore, the property determined by such ability should correlate with the electronegativity. Band gap is an important parameter in determining the practical application of semiconductor materials, which denotes the required energy for an electron to jump from the valence band maximum to the conduction band minimum relating to the attractive power of bonding atoms to their valence electrons. Realizing the prediction of the parameter can provide a clue for the exploitation of new-type semiconductor materials. In this work, we investigate the band gap of semiconductor material from the viewpoint of electronegativity.In the framework of microscopic structure of materials, we analyze the origin of the band gap. Then, we propose that the band gap is determined by two factors:ⅰ) the attractive power of two bonded atoms to their valence electrons;ⅱ) the delocalization degree of the valence electrons between the two bonded atoms. From these two viewpoints, we establish a quantitative relation between electronegativity and the band gap for ANB8-N ternary compound semiconductors. Then, we extend this model to calculate the band gap of ABC2 ternary chalcopyrite compounds. The calculated band gap values of these two type compounds are in agreement with those experimental data.Doping of semiconductor is a key technology for band gap engineering, whereas a simple and effective method is imminently needed in evaluating the band gap of alloyed semiconductors. Hence, we employ our model to predict the band gaps of AxB1-xC and ABxC1-xisovalent substituted semiconductor alloys. Herein, we assume that the doped ions uniformly distribute in the host crystal. Additionally, according to whether AC and BC have the same structure, we divide these alloyed compounds into two categories. The calculated band gap results of these semiconductor alloys agree well with those available experimental data, indicating that this method gives a good description of the band gap and the covalent electronegativity can be effectively used to estimate the band gaps of semiconducting materials. This work provides us an effective method to predict the band gaps of semiconductor materials and gives guidance for the design of new alloyed semiconductors and the determination of macroscopic properties from microscopic structures.更多还原