Interfacial charge transfer mechanism in nanostructured TiO2–ZnS coupled network for single electron device applications

Abstract

We report on the production of nanoporous TiO2 network sensitized by ZnS nanospheres as an idealized scheme to facilitate interfacial charge transfer effects. The nanoporous TiO2 system was fabricated on the 0.1μm thick Al substrate from titanium isopropoxide [Ti(i−OC3H7)] and 1-butanol (C4H9OH) as requisite precursor. The Zn++ ions are internally adsorbed to provide heterogeneous coupled TiO2–ZnS nanosystem. The I-V response shows transistor characteristics which suggests sharp rise in current with forward biasing voltage before attaining saturation. It is expected that with the increase in signal frequency more number of trap carriers being able to follow signal assist higher carrier transfer rate across the interface in the coupled system and hence saturation current (IS) increases. However, in all the cases saturation occurs around finite biasing voltage, i.e., 3.6V. This ensures that the surface states (which normally lie within the forbidden gap and below the conduction bands for electrons) mainly participate in carrier transfer mechanism within the device. A phenomenon in understanding highly controlled interfacial carrier transport process would find potential in nanoelectronics, e.g., single electron transistor and other single electron devices.