Structural and electronic properties of identical-sized Zn nanoclusters grown on Si(111)-(7×7) surfaces

Abstract

Identical-sized Zn nanoclusters have been grown on Si(111)-(7x7) surfaces at room temperature. In situ scanning tunneling microscopy (STM) studies and first-principles total energy calculations show that room-temperature grown Zn nanoclusters tend to form the seven-Zn-atom structure with one excess Zn atom occupying characteristically the center of the cluster. The evolution of the surface electronic structures measured by scanning tunneling spectroscopy reveals that the formation of Zn nanoclusters is responsible for the saturation of the metallic Si adatom dangling bond states at about -0.3 and +0.5 V and causes the semiconducting characteristics of the nanoclusters. Furthermore, the Zn nanocluster in a faulted half unit cell empties the filled surface dangling bond state of the closest edge Si adatoms in the nearest neighboring uncovered unfaulted half unit cells at about -0.3 V, leading to the suppressed height of the closest edge Si adatoms in the filled-state STM images.

Novel Evolution Process of Zn-Induced Nanoclusters on Si(111)-(7×7) Surface

“…It is found that all the Zn 3 Si 1 , Zn 5 Si 2 , and Zn 7 Si 3 clusters could be observed with the tiny number of Zn atoms adsorbed, and the Zn 3 Si 1 and Zn 5 Si 2 clusters gradually disappear when increasing the Zn deposition. As the content of Zn atoms further increases to 0.03 mL, almost no Zn 3 Si 1 and Zn 5 Si 2 clusters are observed, while the surface is dominated by Zn 7 Si 3 clusters, as shown in our previous work [14]. Therefore, we could deduce that, as the increasing of Zn deposition, the additional Zn atoms could gradually merge into the initially formed Zn 3 Si 1 clusters, leading to the formation of Zn 5 Si 2 and finally the Zn 7 Si 3 clusters.…”

“…For type III nanocluster, two groups of empty-and filled-state STM images shown in Fig. 2a-d exhibit almost the same topographic evolution as the previous research [14]. Combined with the results of the simulated STM images as shown in Fig.…”

“…From the viewpoint of practical applications, it is necessary to fabricate stable, ordered, and identical-sized nanoclusters. In the past decade, utilizing the natural template of Si(111)-(797) surface, a number of metal nanoclusters with identical sizes and shapes have been successfully fabricated, such as group IA metals (Na) [11,12], group IB metals (Au) [13], group IIB metals (Zn) [14], group IIIA metals (Al, Ga, Tl, and In) [15][16][17][18][19][20], group IV metals (Pb) [21], and even some 3d ferromagnetic metals (Fe, Co, and Ni) [22][23][24]. By using the ultrahigh-vacuum (UHV) scanning tunneling microscopy (STM) technology combined with the first-principle theoretical simulations, the stable structural configurations of the identical-sized nanoclusters on Si(111)-(797) surface have been clearly illustrated.…”

“…For instance, group IIIA metals (Al, Ga, and In) tend to form the stable Al 6 Si 3 , Ga 6 Si 3 , and In 6 Si 3 nanoclusters with six metal atoms and three displaced Si edge adatoms connecting as a hollow triangle [15][16][17][18][19][20]. However, group IIB metal, Zn, tends to form the stable Zn 7 Si 3 nanoclusters with an excess Zn atom characteristically occupying the center of the hollow triangle [14]. Although the structural configurations have been clearly clarified, the evolution process of these metal nanoclusters was rarely addressed.…”

Semiconducting transport characteristics and their regulation in metal quantum structures

“…Lu课题组 [27] 采用第一性原理模 子结合形成Au 6 Si 3 结构, 表现出了不同于Au体材料的 半导体性质 [48] ; 增大沉积量之后, Au团簇铺满整个Si (111)-7×7表面, 排列成二维蜂窝状Au/Si量子点阵列. 在这个过程中, Si(111)-7×7表面半单胞起到限制并形 成全同Au量子点的作用 [49,50] . 形成的这一层Au量子点 被巧妙地用于饱和Si [51] .…”