Thin film semiconductor nanomaterials and nanostructures prepared by physical vapour deposition: An atomic force microscopy study

Amorphous/nanocrystalline SiOx/CdSe, GeS2/CdSe, SiOx/ZnSe and Se/CdSe amorphous multilayers (MLs) were grown by consecutive physical vapour deposition of the constituent materials at room substrate temperature. A step-by-step manner of deposition was applied for the preparation of each layer (2-10nm thick) of MLs. Surface morphology has been investigated by atomic force microscopy (AFM) in order to get information about ML interfaces. For a scanned area of 3.4 x 4 mu m(2) SiOx/CdSe and GeS2/CdSe MLs showed surface roughness which is around three times greater than the roughness of SiOx/ZnSe MLs. This observation has been connected with effects of both film composition and deposition rate. For a scanned area of 250 x 250 nm(2) the roughness determined in all MLs displayed close values and a similar increase with the ML period. The latter has been related to the flexible structure of amorphous materials. The AFM results, in good agreement with previous X-ray diffraction and high resolution electron microscopy data, indicate that the application of step-by-step physical vapour deposition makes possible fabrication of various amorphous/nanocrystalline MLs with smooth interfaces and good artificial periodicity at low substrate temperatures. (c) 2007 Elsevier Ltd. All rights reserved.