Zinc-nanosystem-structure formation using anodic-oxidized aluminum membranes

Abstract

Abstract-We propose a new method for the formation of zinc nanosystems by condensation of a weakly supersaturated Zn vapor in pores of the anodic-oxidized aluminum membrane (AOA)-silicon substrate system. For this purpose, a weak Zn vapor flow is created by magnetron sputtering of Zn target in a high-purity inert gas atmosphere and maintaining a temperature of the porous AOA membrane outer surface higher than that of the substrate. This drives a directional Zn vapor flow inward membrane parallel to the pore generatrix and favors effective penetration of Zn vapor into the membrane. DOI: 10.1134/S1063785017020201Ordered arrays of metal and semiconductor nanoislands have drawn much research interest due to the good prospects of their use in electronics, optoelectronics, sensors, thin displays, and high-density data-storage media [1,2]. Various metal nanosystems are usually obtained with the aid of nanotemplates of porous anodic-oxidized aluminum (AOA) membranes [3][4][5], electron-beam nanolithography [6][7][8], and self-assembly processes [9,10]. It should be noted that the template approach employing AOA membranes is usually realized by means of electrolytic deposition [4,5]. A necessary condition for implementing this method is a sufficiently high electric conductivity of substrates, which imposes certain limitations on the spectrum of acceptable substrate materials.In contrast to using electrolytic deposition for the formation of ordered Zn nanoisland arrays, we propose a more universal method of substance condensation near thermodynamic equilibrium onto the anodic-oxidized aluminum membrane (AOA)-substrate system. In this case, the conductivity of a substrate is not important and the effective formation of nanosystems in the porous membrane template is favored by creating a directional vapor flow inward into the pores and maintaining vapor supersaturation at the substrate surface higher than that over the outer membrane surface. This approach allows nanosystems to be formed on arbitrary substrates.Some peculiarities of the self-organization of lowdimensional systems during the condensation of weakly supersaturated vapors have been considered in our previous works [11][12][13][14]. Particular interest is related to characteristic features of the formation of Zn nanosystems directly on the outer surface of AOA membranes under conditions of ultimately weak supersaturation of deposited vapors. The choice of zinc is explained by the fact that, in combination with a quite simple oxidation method, this approach can be used for obtaining ZnO nanosystems with a broad spectrum of potential applications.In this context, the main aim of this work was to study the mechanisms of structure formation in Zn nanosystems on the surface of a Si substrate and the outer surface of AOA membranes during the condensation of weakly supersaturated Zn vapors onto the membrane-substrate (AOA-Si) system under conditions of a lower temperature of the substrate surface as compared to that of the outer membrane surface.The condensation of a s...