ABSTRACT
Charge-carrier transport in multilayer structures of Si nanocrystals (NCs) embedded in a SiO(2) matrix grown by magnetron sputtering has been investigated. The presence of two types of Si NCs with different diameters after post-growth annealing is concluded from transmission-electron microscopy and photoluminescence measurements. Based on the electric field and temperature dependences of capacitance and resistivity, it is established that the carrier transport is best described by a combination of phonon-assisted and direct tunneling mechanisms. Poole-Frenkel tunneling seems to be a less suitable mechanism to explain the vertical carrier transport due to the very high values of refractive indices obtained within this model. The possibility to more effectively collect charge carriers generated by light in structures having Si NCs of different size is discussed.
Subject(s)
Crystallization/methods , Membranes, Artificial , Nanostructures/chemistry , Nanostructures/ultrastructure , Nanotechnology/methods , Silicon Dioxide/chemistry , Silicon/chemistry , Electric Capacitance , Electric Impedance , Electron Transport , Macromolecular Substances/chemistry , Materials Testing , Molecular Conformation , Particle Size , Static Electricity , Surface PropertiesABSTRACT
The chemical structure and possible hydro-oxidation of LaNiO(3-delta) films were studied by means of tuneable high-energy X-ray photoelectron spectroscopy using synchrotron radiation. It was shown that the hydroxyl-containing phase, located near the film surface, may be attributed to the lanthanum and nickel hydroxide species. The thickness of a hydroxide-enriched layer was estimated from the oxide/hydroxide ratio measured at normal and grazing conditions. The hydroxide layer thickness was about 2 nm for step and/or exponential hydroxide spatial distribution.
