CDTE Cage-like Nano-dendris And Its AG Doping Theory

As one of typical Ⅱ-Ⅵ semiconductor materials,CdTe nanoclusters have attracted so much concern for their tunability of its electronic properties,especially doped nanoclusters.In this thesis,the（CdTe）_16×N（N=1-3）nanochains,Ag doped（CdTe）_16×N（N=1-2）nanochains and Ag doped（CdTe）₃₄ nanoclusters have been investigated by density functional theory（DFT）.First,by a mass of calculation on（CdTe）i_16×N（N=1-3）nanochains,the results show that（CdTe）_16×N nanochains possess high stability than single cage nanocluster.Besides,the（CdTe）_16×N nanochains stability is not only affected by the number of N but also determined by its assembled mode.Furthermore,the energy gap of nanochains is less than single（CdTe）₁₆ nanoclusters,which shows typical characteristics of quantum dots.Based on the（CdTe）_16×N（N=1-2）nanochains,we substitute one Cd atom by Ag atom and study the effect of Ag substitutional sites on electrical properties.The results show that the binding energy,energy gap and density of state varies with the different substitutional sites directly.One new energy level called acceptor level is introduced in（CdTe）_16×N（N=1-2）nanochains due to Ag doping.The charge distribution of acceptor level mainly comes from the Ag atom and three adjacent Te atoms.In addition,the Te atom which being furthest of Ag atom makes the great contributions.Also,the Ag substitutional doping greatly changes the charge density distributions.Finally,the electrical properties of Ag doped（CdTe）₃₄ nanoclusters have been analyzed in detail.The stable core-cage（CdTe）₃₄ nanoclusters is formed by（CdTe）₂₈ nanocluster and a（CdTe）₆ nanocluster encapsulated inside this cage.The results show that doping improves the initial nanoclusters stability.And the electrical properties vary with the different substitutional sites.