Research On Structure And Electrooptical Characteristic Of Gallium Arsenide Clusters

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.