Planar and coaxial core-shell nanostructures prepared by atomic layer deposition on semiconductor substrates

Abstract

Planar and core-shell structures prepared on the basis of semiconductor nanowires with various semiconductor films constitute a basis for a wide variety of devices for multiple applications. Planar structures have been prepared in this study by atomic layer deposition (ALD) of ZnO and TiO2 thin layers on semiconductor substrates, and their morphologies and the luminescence properties have been compared with those of coaxial core-shell structures obtained by coating of GaAs nanowires with ZnO and TiO2 shells. The prepared structures have been characterized by scanning electron microscopy (SEM), energy dispersive X-ray (EDX) and X-ray diffraction (XRD) analysis, and photoluminescence (PL) spectroscopy. Polarization characteristics of PL bands related to different recombination channels have been investigated in core-shell structures, and the results were analyzed in terms of the either contrast in dielectric constants, or selection rules associated with crystal structure symmetry, or local strain related to specific microscopic structure of recombination centers involved in electronic transitions responsible for specific PL bands.