Title : Morphology, composition and electronic structure of the CdS thin films surface
Abstract:
Nanoheterostructures based on CdS-Me nanofilms are useful in such modern and topical applications as chemical and biometric sensors, in photo-controlled hydrogen production, in memory devices and in CdS solar cells. Among them nanoheterostructures consisting of metallic and semiconductor nanocrystals are of particular importance for photocatalytic applications. However, their photocatalytic efficiency is limited. To increase efficiency It is necessary to suppress the recombination of charge carriers photogenerating so they can participate in the photocatalytic reaction.
This work is devoted to the study of the morphology, composition and electronic structure of the surface of CdS /Mo(111) nanofilms (θ ≈ 100-200 nm). The composition and structure of a massive single crystal CdS sample were studied in the same experimental installation for comparison.
The objects of investigation were CdS films with a thickness of ~ 150-400 nm grown on the surface of Mo(111) by thermal deposition under a vacuum of 10-4 Pa. The research was carried out using Auger electron spectroscopy (AES), atomic force microscopy (AFM), slow elastic electron scattering spectroscopy (SEESS), and ultraviolet photoelectron spectroscopy (UPES).
Analysis of the AFM image shows that the film has a polycrystalline structure consisting of islands with surface diameter of ~ 0.5–2 microns. The boundaries of these islands overlap and continuous polycrystalline film with a surface roughness of ? 6-8 nm is formed.
For the first time, the parameters of the energy bands, the electron density of the valence band and the conduction band were determined by combining the methods of photoelectron and secondary electron spectroscopy.
