STUDY OF THE DEPOSITION OF DOPED COPPER(I) OXIDE BY “AA-MOCVD” AS P-TYPE TRANSPARENT CONDUCTING MATERIAL

This experimental research project is focused on the study of the deposition by Aerosol Assisted Metal Organic Chemical Vapour Deposition (AA-MOCVD) of doped copper (I) oxide, Cu2O, thin films. Among the semiconducting compounds, copper oxide present the most promising electrical, optical and productive features that establish this material suitable as p-type semiconductor. In literature many materials with the required properties are been reported, among them transparent conductive oxide (TCOs) are the most widely used. The developed TCOs are mainly n-type semiconductors, but there is still a lack of p-type TCOs. For this reason, this research is focused on the growth of a p-type transparent conductive oxide. P-type oxides are characterized by metal-oxygen bonds that form deep acceptor levels, which limit the holes mobility. Cu (I) oxides have one of the lowest ionic aspect, therefore it is one of the most promising candidates as p-type transparent semiconductors. This research will be aimed on the optimization of the deposition and the characterization of pure and doped-copper oxide. In the first chapter of this work, there will be an overlook of transparent conductive material and of the so-called transparent electronics. It will contain also a summary of the physical properties of the cuprous oxide, how conduction takes place in this material and there will be special focus on the already existing doped copper oxide systems and their possible applications. In the chapter II there will be the description of the AAMOCVD system and the experimental setup followed by a complete explanation on how deposition occurs. Moreover, the used characterization tools will be described with an explanation of how these systems work. The third chapter is dedicated to the explanation of the pure copper oxide deposition and its optimization and then we will illustrate the results of these depositions. In the work on Cu2O, we performed different depositions to establish the optimized deposition conditions trying to get the best films in terms of conductivity and optical transmittance. Once obtained the best deposition conditions, we focused the attention on the deposition of doped Cu2O, with the purpose to enhance the electrical and optical properties of the films. The 4th chapter will be dedicated to the study of the effect of the tin as dopant on the copper oxide deposition. This chapter will be divided in two sections. The first study aims to test and to investigate the incorporation of tin in the film using different chemical precursors starting from the obtained results from DBTD. The second section will be related to the effect of the precursor already studied in Resende1, the Dibutyltin Diacetate (DBTD) as precursor for the tin doping. The study of lithium doped copper oxide (Li/Li+Cu) is described in the chapter V, discussing the results obtained with this dopant through the analysis of the produced films using the characterization tools described in chapter II, investigating the main parameter in terms of electrical and optical properties. For each chapter, the results will be presented divided between structural, morphological then electrical and optical properties of the as deposited samples. Moreover, every chapter will contain also the annealing studies performed on the samples.