The Application of Electric Fields to Aerosol Assisted Chemical Vapor Deposition Reactions

Abstract

Chemical vapor deposition methodologies are widely employed in a variety of fields such as microelectronics and glazing. Control of film growth and microstructure, and hence film properties, may be limited by precursor properties such as volatility or decomposition chemistry. In this paper we report how the incorporation of an applied electric field to aerosol assisted chemical vapor deposition reactions of vanadyl acetylacetonate in alcohols can influence the microstructure and growth of thin films of vanadium dioxide in unusual and sometimes unexpected ways. The films were characterized using scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and Raman spectroscopy.

Electric field assisted aerosol assisted chemical vapour deposition of nanostructured metal oxide thin films

“…Previous investigations [10][11][12][13] have shown that the application of an electric field during a CVD reaction influences the crystallographic orientation, microstructure and subsequent properties of the deposited materials. Indeed it is well known that sensor microstructure plays an important role in determining the gas response of a gas sensing material [24].…”

“…Indeed it is well known that sensor microstructure plays an important role in determining the gas response of a gas sensing material [24]. We have suggested previously that a variety of phenomena may be occurring when an electric field is applied to CVD growth [10][11][12][13]. Applied electric fields can cause an increase in growth rate and nucleation rate leading to pseudo dendritic type morphologies as a result of accelerating gas phase species towards the surface [10].…”

“…We have suggested previously that a variety of phenomena may be occurring when an electric field is applied to CVD growth [10][11][12][13]. Applied electric fields can cause an increase in growth rate and nucleation rate leading to pseudo dendritic type morphologies as a result of accelerating gas phase species towards the surface [10]. We consider this to be the result of an interaction between a permanent or induced dipole in the CVD precursor species and the applied electric field; greater kinetic energy would increase the probability of nucleation on the gas sensor substrate surface increasing film growth rate as well as leading to a reduction in the scale length of the deposited particles.…”

“…The experiment was carried out in a cold wall reactor, which has been previously reported [10]. The reactor was a cylindrical stainless steel tube with dimensions of 3 cm diameter and 36 cm length.…”

“…The effect of an electric field in chemical vapour deposition reactions of any kind is largely unknown; Williams et al noted that whilst trying to follow WO 3 film growth from an aerosol assisted chemical vapour deposition (AACVD) using impedance measurements, the bias of the measuring circuit led to a change in film microstructure [9]. We have conducted a number of studies on the effect of electric fields in the chemical vapour deposition reactions to produce various metal oxides [10][11][12][13]. In this paper we describe the use of electric field assisted chemical vapour deposition to produce thin films of vanadium, titanium and tungsten oxides and their application as metal oxide gas sensors.…”