A Study on Impact of Process Parameters to Metal Organic Chemical Vapor Deposition Grown (002) Zinc Oxide Thin Films,at 320 deg C

摘要

This paper reports preparation of highly oriented (002) ZnO films by atmospheric [pressure CVD at 320 deg C,which is far below previous reported values.In this study,a cold wall horizontal system was used to thennally decompose sublimed zinc acetylacetonate (Zn(acach,Zn(C_5H_7O_2)_2) vapor,and reacted with water vapor to produce ZnO films at temperatures above 320 deg C.Through experimental data,we discovered that low deposition temperature,using water ,vapor as co-reactant and substrates with ZnO buffer layer pre-coated by PVD are the key factors rto prepare (002) ZnO films.By using Si(100) pre-coated with sputtered ZnO amorphous buffer layer as substrates,the ZnO growth rate is highest.While using copper oxide pre-coated Si substrates gave the lowest growth rate,and deposited ZnO film is amorphous.Considering r influence of CVD co-reactant,using Zn(acac)_2 and water vapor gives higher growth rate and better crystallinity than CVD using Zn(acac)_2 and oxygen.Water vapor may supply hydrogen to react with released acetylacetonyl ligand (C_5H_7O_2),and help the fonnation of stable acetylaceton (C_5H_8O_2) molecule.DPA shows that film contain 46% O and 54% Zn.XPS of Zn Auger identified the valence of Zn being Zn~(2+).It seems that excessive Zn might present as discrete Zn~(2+) dispersed between ZnO lattices.