Method of forming a zinc oxide coated article

#The present invention is related to a method of depositing a zinc oxide coating on a transparent substrate; more particularly, it is related to a chemical vapor deposition method of depositing a zinc oxide coating on a glass substrate.

#Deposition of metal oxide coatings reacted with H2O has been reported in the patent literature. For example:

#U.S. Pat. No. 4,751,149 describes a chemical vapor deposition (CVD) process for depositing zinc oxide films having certain properties which make them useful in photoconductive applications, such as in solar cells, and other photovoltaic devices. The deposition process includes introducing an organozinc compound, an oxidant and an inert carrier gas into a chamber containing a substrate heated to a temperature in the range of about 60° C. to 350° C. The resulting zinc oxide films are said to have a resistivity in the range of about 10−4 to 10−2 ohm centimeter. Such films contain hydrogen and may be fabricated to contain a Group III element by introducing volatile Group III compounds into the chamber along with the organozinc compound and oxidant.

#While zinc oxide coatings and deposition methods are known, cost effective methods of making pyrolytic zinc oxide coatings, at commercially viable growth rates, during the glass making process on a float glass manufacturing line, have not previously been known. The present invention overcomes the previous obstacles of making such zinc oxide films at commercially viable growth rates.

#While any suitable method of atmospheric pressure chemical vapor deposition may be utilized in connection with the present invention, the method of deposition disclosed in U.S. Pat. No. 6,268,019 to Atofina Chemicals, Inc. is preferred. The '019 patent is incorporated herein by reference, in its entirety. The method of the '019 patent has been shown to be capable of depositing metal oxide films of various kinds, at commercially useful growth rates, for example, at greater than 5 nm/sec. The precursor gases are delivered to a gas mixing chamber a predetermined distance above a surface of the substrate. The precursor gases are mixed together in the gas mixing chamber to form a precursor mixture which, upon exiting the gas mixing chamber, contacts the surface of the substrate as it moves outside of and past the gas mixing chamber. The deposition method of the '019 patent also has the advantage of being able to vary the mixing time of the reactant materials which, in turn, allows “tuning” of the properties of, in this instance, zinc oxide coatings. In particular, the present invention demonstrates the benefits of utilizing water to enhance the growth rates of zinc oxide films, which benefits will be discussed in greater detail herein.

#Such zinc oxide coated glass products are useful as low emissivity and/or solar control layers in architectural window applications. Other potential applications of this transparent conducting oxide include: photovoltaic devices, solid-state lighting (LEDs and OLEDs), induction heating, flat panel displays and touch panel screens, and transparent thin film transistors (TFT) that have applications in RFID tags and integrated circuits.