【作者】 马德明；

【导师】 施卫； 李恩玲；

【作者基本信息】 西安理工大学 ， 微电子学与固体电子学， 2009， 博士

【摘要】 砷化镓材料作为一种直接带隙双能谷化合物半导体材料,以其优越的光电特性在微电子和光电子学领域有着广泛的应用。非掺杂半绝缘砷化镓材料的团簇深能级缺陷影响着材料和器件的光电性能,深入研究砷化镓团簇的结构和性质,不论对砷化镓纳米材料的制备和应用,还是对半绝缘砷化镓材料深能级缺陷的微观结构和光电特性的分析,都有着极其重要的意义。论文利用杂化密度泛函理论中的B3LYP方法对砷化镓团簇的几何结构和振动频率进行了计算,分析了团簇基态结构的稳定性规律,研究了团簇与半绝缘砷化镓深能级缺陷的关系,讨论了半绝缘砷化镓材料吸收大于本征吸收长波限激光的微观过程,取得以下成果：1计算了GamAsn(m=1-2,n=1-7)中性团簇和Ga2Asn(n=1-7)正负离子团簇的基态结构,结果表明团簇结构中As-As和As-Ga键比Ga-Ga键稳定,团簇得失电子成为正负离子团簇,离子团簇自身所带电荷的静电库仑作用使得团簇的结构发生畸变,并影响着团簇的性质和规律。2 GamAsn(m=1-2,n=1-7)中性团簇的结构稳定性随团簇的As原子数增大而呈奇偶交替变化规律,As原子为偶数的团簇比As原子为奇数的团簇的结构稳定；具有相同原子数的不同系列团簇,As原子数多的团簇比As原子数少的团簇稳定。3 Ga2Asn(n=1-7)中性团簇和正离子团簇的结构稳定性随团簇原子数变化的规律一致,总原子数为偶数的团簇比总原子数为奇数的团簇稳定,负离子团簇刚好相反,即总原子数为奇数的团簇比原子数为偶数的团簇稳定；原子数相同的团簇,其结构稳定性的关系为：负离子团簇>中性团簇>正离子团簇。4 GamAsn(m=1-2,n=1-7)团簇的能隙差随As原子数的增大呈奇偶交替变化规律,其中As原子为偶数的团簇比As原子为奇数的团簇的能隙差大,化学活性弱,化学稳定性高；具有相同As原子数的GaAsn(n=1-7)团簇和Ga2Asn(n=1-7)团簇,As原子为偶数的两个团簇比As原子为奇数的两个团簇的能隙差差值小；原子数相同的Ga2Asn(n=1-7)离子团簇与中性团簇相比,能隙差差异大,即团簇得失电子对团簇的化学稳定性的影响大。5 GamAsn(m=1-2,n=1-7)团簇的热稳定性随团簇总原子数的增大呈奇偶交替变化规律,其中总原子数为偶数的团簇比总原子数为奇数的团簇的热稳定性好。对于Ga2Asn(n=1-7)离子团簇,正负离子团簇热稳定性随总原子数的变化规律一致,且与中性团簇相反,即总原子数为奇数的团簇比总原子数为偶数的团簇的热稳定性好。6提出了半绝缘砷化镓EL2深能级缺陷的离子团簇微观构型,给出了半绝缘砷化镓材料吸收大于本征吸收限激光的微观过程。更多还原

【Abstract】 The gallium arsenide is a compound semiconductor material with direct bandgap and two-valley; it is widely applied in the field of microelectronics and optoelectronics because of its superior electrooptical characteristics. The deep-level cluster defects of undoped semi-insulating gallium arsenide materials affects the electrooptical properties of materials and devices, the further study on the structure and properties of gallium arsenide clusters will play an extremely important role in the preparation and application of gallium arsenide nanomaterials or the analysis of microstructure and electrooptical characteristic of the deep-level defects of semi-insulating gallium arsenide materials.The method of B3LYP in hybrid density functional theory (DFT) was used to optimize the geometric configuration and compute the vibration frequency of gallium arsenide clusters in the paper, the stabile regularities of the ground-state structures of clusters was analyzed, the relation between the clusters and the semi-insulating gallium arsenide deep-level defects was studied, the micro-process of the semi-insulating gallium arsenide materials absorbing the lasers which wavelength is above this permits absorption of long-wave limit was discussed. The results were found as follows:The ground-state structures of GamAsn(m=1-2, n=1-7) neutral clusters and Ga2Asn(n=l-7) positive and negative ion clusters were obtained. The results showed that As-As and As-Ga bond was more stable than Ga-Ga bond in those clusters. The clusters advantages and disadvantages of electronic became ion clusters. The electrostatic coulomb interaction which ion cluster itself brought about by charge resulted made the clusters structures distort, and the interaction also affected the nature and patterns of clusters.Their structure stability show a certain degree of even/odd alternation with the number of arsenide atoms in the GamAsn(m=1-2, n=1-7) neutral clusters. The structure with even number of arsenide atoms was more stable than those with odd number of arsenide atoms, the structure with more number of arsenide atoms was more stable than those with less number of arsenide atoms in different series clusters with the same totals atoms.Their structure stability show the same regularity in the Ga2Asn(n=1-7) neutral and positive ion clusters, the structure with even number of total atoms was more stable than those with odd number of total atoms, on the contrary, the structure with odd number of total atoms was more stable than those with even number of total atoms in Ga2Asn- clusters. The order of structure stability with the same number atoms clusters is that anion clusters was more stable than those of neutral clusters and positive ion clusters, positive ion clusters was the worst in those clusters.Their energy gap show a certain degree of even/odd alternation with the number of arsenic atoms in the GamAsn(m=1-2, n=1-7) clusters, the Egap with even number of arsenic atoms was more large than those with odd number of arsenide atoms, the chemical activity of the former is relative weak, and its chemical stability is much stronger. In addition, there is relatively less Egap difference between the atoms with even number than those with odd number atoms in the GaAsn(n=1-7) and Ga2Asn (n=1-7) clusters with the same number of arsenic atoms; there is relatively large Egap difference between the Ga2Asn(n=1-7) positive and negative ions cluster and neutral clusters with the same atoms, in other words, cluster advantages and disadvantages of electronic has a large affect on its chemistry stability.Their thermal stability show a certain degree of even/odd alternation with total atom numbers of the clusters in the GamAsn(m=1-2, n=1-7) clusters, the thermal stability with even number of total atoms was stronger than those with odd number of total atoms. Their thermal stability show the same regularity in the Ga2Asn(n=1-7) positive and negative ion clusters, the regularity is contrary to those of the neutral clusters, namely, the thermal stability with odd number of total atoms was stronger than those with even number of total atoms.Ion cluster micro configuration of semi-insulating gallium arsenide EL2 deep-level defects was proposed; the micro-process of the semi-insulating gallium arsenide materials absorbing the lasers which wavelength is above this permits absorption of long-wave limit was given.更多还原