Low temperature method of making a zinc oxide coated article

[0001] The present invention relates to a method for depositing a zinc oxide coating on a transparent substrate. More particularly, the invention relates to a method for chemical vapor deposition of a zinc oxide coating on a transparent substrate, the coating being modified to form a zinc oxide coating having a set of desirable properties.

[0002] The development of zinc oxide coatings by means of CVD has been described in the scientific literature. For example, Smith, Frank TJ, "Metalorganic chemical vapor deposition of oriented ZnO films over large areas," Applied Physics Letters, Vol. 43, No. 12 (1983) pp. 1108-1110, describes a method of organometallic chemical vapor deposition to producing Zn oriented films orientated with respect to the axis c in a system similar to that which is commercially available for SiO2 deposition. It is believed that the films obtained are of uniform thickness and that they adhere to different substrates.

[0003] Gerfin and Dahmen in CVD of Nonmetals (WS Rees, Jr. ed., VCH Publishers, Inc., New York, NY, 1996), Chapter 3, pp. 180-185, describe the work of numerous scientists regarding the use of various chemical techniques of preparing layers of zinc oxide. The use of dialkylzinc compounds and various oxygen-containing compounds is discussed.

[0004] Deposition of films from zinc oxide has also been described in the patent literature.

[0005] Patent description Ser. Am. No. 4,751,149 belonging to Vijaykumar, P., et al. describes a low temperature (200 ° C or less), low pressure (2 torr or less), a static method of deposition of zinc oxide films, using an organozinc compound and water, conducted under an inert gas atmosphere. It is believed that the resulting zinc oxide film has a low electrical resistance, which can be changed by the addition of element from group 13.

[0006] Patent description Ser. Am. No. 4,990,286 and Solar Cells, 30 (1991) 437-450 belonging to Gordon, R., et al. describes deposition of fluorine doped zinc oxide films by chemical vapor deposition from vaporous mixtures of zinc, oxygen and fluorine-containing compounds.

The films produced are considered to be well-conducting electric current, transparent to visible light, reflecting infrared radiation and absorbing ultraviolet light. Temperature sensitive substrates are considered suitable for the process of the invention.

[0007] Patent description Ser. Am. No. 5,306,522 describes methods for coating a substrate, in particular, substrates comprising screened surfaces coated with zinc oxide containing coatings. The described methods include means for contacting the support with the zinc oxide precursor, preferably maintaining the substrate precursor coated under equilibrium conditions of the coating, then oxidizing the precursor to form a coating comprising zinc oxide. Also described are substrates coated by this method for use in various applications.

[0008] Patent description Ser. Am. No. 5,407,743, which refers to the above-mentioned US Pat. Ser. Am. No. 5,306,522, contains additional information regarding especially products coated with zinc oxide produced by the method described.

[0009] Patent description Ser. Am. No. 6,416,814 owned by Giolando, D. describes the use of coordinating compounds of tin, titanium and zinc as metal oxide precursor compounds in a method for the production of high quality metal oxide coatings upon contact with a heated substrate.

[0010] US-A-4 508 054 discloses an apparatus for depositing a mineral oxide coating on a substrate by means of CVD, wherein the reactive gases are to be counter-current to provide, by the turbulent effect, the occurrence of almost immediate mixing reactants.

[0011] Durable, coated, transparent backing materials are increasingly desirable. It would be desirable to have zinc coated transparent substrate materials exhibiting high visible light transmittance, low emission properties and / or solar control properties, high electrical conductivity / low surface resistance, and which could be produced in an economical manner.

BRIEF DESCRIPTION OF THE DRAWINGS [0012] Various other objects, properties and associated advantages of the present invention will be more fully appreciated when the invention becomes better understood from the following detailed description when considered together with the accompanying drawing.

[0013] The figure shows schematically the nozzle of the dynamic coating device used in example 21 according to the invention.

SUMMARY OF THE INVENTION [0014] The present invention relates to a method for the production of a transparent product coated with zinc oxide having a low electrical resistivity that has the properties described in claim 1. 1. Preferred embodiments of the present method are defined in the dependent claims.

DETAILED DESCRIPTION OF THE INVENTION [0015] This invention provides an economical method of making pyrolytic zinc oxide coatings at commercially viable growth rates on transparent substrate materials having a glass transition temperature, Tg (softening point) of less than 400 ° C. The present invention overcomes the earlier obstacles to the production of such doped zinc oxide films on a plurality of possible transparent substrates with a zinc oxide film deposited at a substrate temperature of less than 400 ° C, preferably between 80 ° C and 400 ° C.

[0016] While any suitable method of atmospheric pressure chemical vapor deposition can be used in conjunction with the present invention, the deposition process disclosed in US Patent Ser. Am. No. 6,268,019 to Atofina Chemicals, Inc.

The method of the '019 patent was found to be capable of depositing various types of metal oxide films at commercially viable growth rates, e.g., at greater than 5 nm / sec. The deposition process of the '019 patent also has the advantage of being able to vary the mixing time of the reacting materials, which in turn makes it possible to regulate the properties, in this case, zinc oxide coatings. In particular, the present invention presents the advantages of using multiple precursor compounds, which benefits will be discussed in more detail here. Such products coated with zinc oxide, when doped, are useful as, for example, transparent conductive oxide. The undoped zinc oxide coatings may be useful in a variety of multiple shell configurations for adjusting the refractive index. [0017] More specifically, the possible uses of doped zinc oxide coatings made by the method of the present application include, but are not limited to, thin-film and organic (OPV) photovoltaic devices, flat displays, luminous solids (LED and OLED), panels with a touch screen, thin-film transistors (TFT), which are used in RFID markers and integrated circuits as well as in a multitude of low-emissivity coatings and solar control.

[0018] Suitable zinc-containing compounds include, but are not limited to, compounds of general formula R¹R²Znlz or R¹R²Zn- [R³R⁴N (CHR⁵) N (CH2) m (CHR⁶) n⁷R⁸], where R^1-8 may be the same or different alkyl or aryl groups, such as methyl, ethyl, isopropyl, n-propyl, n-butyl, sec-butyl, phenyl or substituted phenyl, and may contain one or more fluorine-containing substituents, L is based on oxygen, a commercial, neutral ligand such as tetrahydrofuran, methyltrihydrofuran, furan, diethyl or dibutyl ether, methyl tert-butyl ether, or dioxane and z = 0-2. R⁵ and R⁶ may be H or alkyl or aryl groups, n may be 0 or 1, and m may be 1-6 if n is 0, and m may be 0-6 if n is 1.

[0019] Other suitable zinc compounds may include an alkyl hydrocarbon alkyl glycol ether having the formula:

R⁹2Zm [R¹⁰O (CH2) 2 O (CH 2) 2 OR¹⁰], where R⁹ means a short-chain, saturated organic group having 1 to 4 carbon atoms and R¹⁰ is a short-chain, saturated organic group having 1 to 4 carbon atoms. Preferably, R⁹ means a methyl or ethyl group (C2H₅-) and R¹⁰ means a methyl group (CH3-) and refers to (DEZ) diethylzinc diglyme of the formula:

Et2Zm [CH3O (CH2) 2O (CH2) 2OCH3] Other tridentate ligands capable of chelating a dialkylzinc moiety that may be useful in connection with the present invention include: compounds of the formula [R¹¹C (OR¹²) 3], where R¹¹ is H or a short-chain, saturated organic group having 1 to 4 carbon atoms or a phenyl group and R¹² is a short-chain, saturated organic group having 1 to 4 carbon atoms as described above, wherein R¹¹ and R¹² they may be the same or different, triamine ligands of the formula [R¹³2 N (CH₂)₂N (R¹⁴) (CH₂)₂NO¹³2], where R¹³ is a short-chain, saturated organic group having 1 to 4 carbon atoms and compounds wherein R¹⁴= phenyl (C6H5) or substituted phenyl. Diphenyl zinc compounds may also be useful in connection with the present invention.

[0021] Suitable oxygen-containing compounds include, but are not limited to: organic acetates, for example, ethyl acetate (EtOAc), t-butyl acetate (t-BuOAc), alcohols (including perfluorinated derivatives), oxygen and water: what is preferred is H2O or an alcohol containing water.

[0022] An inert carrier gas such as nitrogen, helium, or the like may also be used as a component of the gaseous stream of the reactant of the present invention.

[0023] If the transparent substrate material is glass, it can be formed by any suitable method, but is preferably a continuous glass ribbon formed by a well-known flat glass process as described in US Pat. Ser. Am. No. 3,356,474, 3,433,612, 3,531, 274 and 3,790,361, each of which is incorporated herein by reference in its entirety.

Other suitable substrate materials include, but are not limited to, polymethyl methacrylate (pMMA), polyethylene terephthalate (PET), polyamides, polyimides, polylactic acid (PLA) and polycarbonate materials.

[0025] If desired, the zinc oxide coating can be given properties, such as at least the conductivity of the electric current, by adding one or more dopant materials to one or more gaseous reactant streams. Suitable admixtures include, but are not limited to, fluorine-containing compounds, and metal-containing precursors of group 13:

Suitable fluorine-containing compounds include, but are not limited to:

difluoromethane, 1,1-difluoroethane, 1,1,1,2-tetrafluoroethane, 1,1,1,2,2-pentafluoroethane, 1,1,1-trifluoroethane, 1,1,1,3,3-pentafluoropropane, fluoroethylene, 1,1-difluoroethylene,

1.1.1.2.3.3.3- heptafluoropropane, 1,1,1,2,2,3,3-heptafluoropropane, hexafluoropropene, 3,3,3-trifluoropropene, perfluorocyclopentene, perfluorobutadiene,

1,1,1,3,3,3-hexafluoro-2-propanol, 1,1,1,3,3,3-hexafluoro-2-methyl-2-propanol, hexafluoropropene oxide, 2,2,3,4 4,4-hexafluoro-1-butanal, 1,1,2,2,3,4hexafluoro-3,4-bis (trifluoromethyl) cyclobutane, hexafluoro-2-butine, hexafluoroacetone, hexafluoroglutaric acid anhydride, trifluoroacetic anhydride, trifluoroacetyl chloride, 2,2,2-trifluoroethanol, 1,1,1-trifluoroacetone, trifluoromethane, 1,1,1-trifluoro-2-propanol, 3,3,3-trifluoropropionic acid,

3.3.3- trifluoropropne, trifluoroamine, hydrogen fluoride, trifluoroacetic acid,

1.1.1.3.3- pentafluorobutane and 1,1,1,2,3,4,4,5,5,5-decafluoropentane.

Suitable precursors comprising a metal of group 13 include those of general formula R¹⁵(3-n) MR¹⁶n or R¹⁵3M (L) wherein M = one of B, Al, Ga, In or T1, R¹⁵ is alkyl or aryl or a halide or an alkoxylate group, R¹⁶ is H, alkyl, aryl, a halide or a diketone group of the formula (R.¹⁷C (O) CR¹⁸C (O) R¹⁹) in which R^17-19 may be the same or different and represent H, alkyl or aryl groups (including cyclic and partially perfluorinated and perfluorinated derivatives), wherein L is an oxygen-based commercial neutral ligand, such as methylthihydrofuran, tetrahydrofuran, furan, diethyl ether or dibutyl, dioxane and n = 0-3. Me₂Ga (hfac) (hfac = hexafluoroacetylacetonate, F₃CC (O) CHC (O) CF₃), Me₂Ga (acac), Et₂Al (acac) (acac = acetylacetonate, H₃CC (O) CHC (O) CH₃), and Et₂AlCl are preferred compounds of group 13.

[0026] It is preferred that the zinc oxide films produced in the process of the present invention be doped with one or more of the abovementioned additive materials.

[0027] The following non-limiting examples illustrate certain aspects of the present invention.

Examples [0028] Example 21 is an example of the invention.

[0029] The APCVD apparatus used in Examples 1-20 is similar to that described in US Pat. Ser. Am. 6268019 B1. The key feature of the apparatus is the ability to control the mixing time of gaseous reactants by feeding the pairs separately to the coating nozzle. In these experiments the coating nozzle consists of concentric tubes: 3/8 "tube inserted into 1" tube by press fit, which allows adjusting the length of the mixing zone and a 1.5 "outer tube connected to the outlet blower to remove byproducts and unreacted vapors. The films obtained from this nozzle configuration were round with a diameter of approximately 1.5 ".

[0030] The APCVD apparatus used in example 21 is shown in the figure and consists of a single slit coating device 10 that comprises a mixing chamber 12 where two separate precursor streams can be combined in a controlled manner before contacting the substrate surface 14, which it is supported on the nickel heating block 15. The first stream is introduced through the head 16 and flows down through the distribution plate 17, while the second flow is introduced through the lateral inlet slots 18. The mixing chamber has a length of 1.25 inches. For a total carrier gas flow of 15 l / min, the mixing time of the two precursor streams is approximately 280 milliseconds. The deposition by-products and unreacted precursor vapors are removed through two exit slots 20 (adjacent to the coating slot 22) connected to an outlet blower (not shown). The films obtained from this nozzle have a width of approximately 4-inches. Heated substrates can be transported below the nozzle to cover different lengths.

[0031] Examples 1-5 describe the deposition of zinc oxide at 365 ° C and at different H2O / Zn ratios in the range between 3 and 12, using the previously described deposition method. Examples 6-10 describe the deposition of zinc oxide at 280 ° C and different H2O / Zn ratios between 3 and 12. Examples 11-15 describe the deposition of zinc oxide at 190 ° C and various H2O / Zn ratios in the range of: between 3 and 12. Examples 16-17 describe the deposition of zinc oxide at 155 ° C and at different H2O / Zn ratios between 3 and 6. Examples 18-20 describe the deposition of ZnO doped Al at 200 ° C. Example 21 describes the deposition of ZnO doped Ga at a temperature of about 200 ° C. For all the above examples,

Examples 1 - 5 [0032] Borosilicate glass (1.1 mm thick) was heated to 365 ° C (measured on the surface of the substrate using a contact thermocouple) on a nickel heating block. Gas mixture 0.08 mol% Et₂ZnYEEDA (TEEDA =

N, N, N ', N'-tetraethylethylenediamine) in a 30 L / min nitrogen carrier gas at 180 ° C was fed through the primary chemical inlet of the coating nozzle. In a separate inlet, a gas mixture of 0.24 mol%, respectively

About 97% mole of steam (evaporated in vaporizer 1) in a carrier gas in the form of nitrogen of 2.2 L / min flow was fed into the inner tube of the coating device, resulting in H2O / Zn ratios between 3 and 12.

[0033] The inner feed tube has been adapted so that the length of the mixing zone is 15 cm. The carrier gas flows in the form of nitrogen have been chosen so that the feed rates on the two inlets are approximately equal. Under these conditions, the face speed at the nozzle outlet of the coating device was approximately 100 cm / s, which correlates with a reactant mixing time of approximately 150 ms (milliseconds).

[0034] A gaseous mixture containing water vapor was pre-dosed for 5 seconds on the substrate immediately before the start of the Zn precursor flow. The deposition rates were in the range between 8.87 nm / s and 6.45 nm / s, with the highest deposition rate occurring when the H2O / Zn ratio was 9 and the lowest settling rate occurring when the H2O / Zn ratio was 12 .

Examples 6-10 [0035] Borosilicate glass (1.1 mm thick) was heated to a temperature of 280 ° C (measured on the substrate surface by means of a contact thermocouple) on a nickel heating block. Gas mixture 0.08 mol% Et₂ZmTEEDA in a carrier gas in the form of nitrogen at 30 L / min at 180 ° C was fed through the primary chemical inlet of the coating nozzle. In a separate inlet, a gas mixture of 0.24 mol% to 0.97 mol% water vapor (evaporated in vaporizer 1) in a carrier gas in the form of nitrogen of 2.2 L / min flow was fed into the inner tube of the device on the coating, resulting in H2O / Zn ratios between 3 and 12.

[0036] The inner feed tube has been adapted so that the length of the mixing zone is 15 cm. The carrier gas - nitrogen flows were selected so that the feed rates on the two inlets were approximately equal. Under these conditions, the face speed at the nozzle outlet of the coating device was approximately 100 cm / s, which correlates with a reactant mixing time of approximately 150 ms (milliseconds). The substrate was pre-metered in water vapor for 5 seconds immediately prior to starting the flow of the Zn precursor to the substrate. The deposition rate was between 9.28 nm / s and 6.84 nm / s, with the highest deposition rate occurring when the H 2 O / Zn ratio was 3 and the lowest deposition rate occurring when the H 2 O / Zn ratio was 12 .

Examples 11-15 [0037] Borosilicate glass (1.1 mm thick) was heated to 190 ° C (measured on the substrate surface by means of a contact thermocouple) on a nickel heating block. Gas mixture 0.08 mol% Ht₂ZirTT.HID \ in carrier gas in the form of nitrogen at 30 L / min at 180 ° C was fed through the primary chemical inlet of the coating nozzle. In a separate inlet, the gas mixture, suitably 0.24 mol% to 0.97 mol% water vapor (evaporated in vaporizer 1) in carrier gas in the form of nitrogen at a flow rate of 2.2 1 / min, was fed into the inner tube of the coating apparatus.

[0038] The inner feed tube has been adapted so that the length of the mixing zone is 15 cm. The carrier gas flows in the form of nitrogen have been chosen so that the feed rates on the two inlets are approximately equal. Under these conditions, the face speed at the nozzle outlet of the coating device was approximately 100 cm / s, which correlates with a stirring time of the reactant of approximately 150 ms.

[0039] The substrate was pre-metered in water vapor for 5 seconds immediately prior to starting the flow of the Zn precursor to the substrate. The deposition rates ranged between 8.50 nm / s and 8.02 nm / s, with the highest deposition rate occurring when the H 2 O / Zn ratio was 9 and the lowest deposition rate occurring when the H 2 O / Zn ratio was 6 .

Examples 16-17 [0040] Borosilicate glass (1.1 mm thick) was heated to 155 ° C (measured on the surface of the substrate by means of a contact thermocouple) on a nickel heating block. Gas mixture 0.08 mol% Ht₂ZirTT.HID \ in carrier gas in the form of nitrogen at 30 L / min at 180 ° C was fed through the primary chemical inlet of the coating nozzle. In a separate inlet, the gas mixture, suitably 0.24 mol% to 0.49 mol% water vapor (evaporated in vaporizer 1) in carrier gas in the form of nitrogen at a flow rate of 2.2 1 / min was fed into the inner tube of the coating device.

[0041] The inner feed tube has been adapted so that the length of the mixing zone is 15 cm. The carrier gas flows in the form of nitrogen have been chosen so that the feed rates on the two inlets are approximately equal. Under these conditions, the face speed at the nozzle outlet of the coating device was approximately 100 cm / s, which correlates with a stirring time of the reactant of approximately 150 ms.

[0042] The substrate was pre-metered in water vapor for 5 seconds immediately before the start of the Zn and Ga precursor flow. The deposition rates were in the range between 5.82 nm / s and 6.14 nm / s, with the highest deposition rate occurring when the H 2 O / Zn ratio was 3 and the lowest settling rate occurring when the H 2 O / Zn ratio was 6.

Table 1

<td>Examples</td><td>Temp. deposition (° C)</td><td>Ratio H₂O / Zn</td><td>Deposition rate (nm / s)</td>

<td>1</td><td>365</td><td>6</td><td>7.71</td>

<td>2</td><td>365</td><td>3</td><td>7.32</td>

<td>3</td><td>365</td><td>9</td><td>7.87</td>

<td>4</td><td>365</td><td>12</td><td>6.45</td>

<td>5</td><td>365</td><td>6</td><td>6.84</td>

<td>Examples</td><td>Temp. deposition (° C)</td><td>Ratio H₂O / Zn</td><td>Deposition rate (nm / s)</td>

<td>6</td><td>280</td><td>6</td><td>7.47</td>

<td>7</td><td>280</td><td>3</td><td>9.28</td>

<td>8</td><td>280</td><td>9</td><td>8.73</td>

<td>9</td><td>280</td><td>12</td><td>6.84</td>

<td>10</td><td>280</td><td>6</td><td>8.81</td>

<td>11</td><td>190</td><td>6</td><td>8.02</td>

<td>12</td><td>190</td><td>3</td><td>8.18</td>

<td>13</td><td>190</td><td>9</td><td>8.5</td>

<td>14</td><td>190</td><td>12</td><td>8.18</td>

<td>15</td><td>190</td><td>6</td><td>8.34</td>

<td>16</td><td>155</td><td>6</td><td>5.82</td>

<td>17</td><td>155</td><td>3</td><td>6.14</td>

[0043] As can be seen in the above examples, the fastness of ZnO deposition was relatively uniform at commercially available deposition rates between 190 ° C and 365 ° C. When the temperature of the substrate dropped below 190 ° C, a significant decrease in the deposition rate was observed.

Example 18 [0044] Borosilicate glass (0.7 mm thick) was heated to a temperature of 200 ° C (measured on the substrate surface by means of a contact thermocouple) on a nickel heating block. Gas mixture 0.45 - mole% Ht₂ZirTMPDA (TMPDA = 10 N, N, N ', N'-tetramethyl-1,3-propanediamine) and 0.0072 mol% Et2Al (acac) in carrier gas in the form of nitrogen at a flow rate of 30 l / min at 180 ° C it was administered by the original chemical inlet of the coating nozzle. In a separate inlet, a gas mixture of 2.73 mol% water vapor (evaporated in vaporizer 1) and 1.59 mol% hexafluoropropene was fed into the inner tube of the coating apparatus in the carrier gas in the form of nitrogen at a flow rate of 2.2 l / min.

[0045] The inner feed tube has been adapted so that the length of the mixing zone is 15 cm. The carrier gas flows in the form of nitrogen have been chosen so that the feed rates on the two inlets are approximately equal. Under these conditions, the face speed at the nozzle outlet of the coating device was approximately 100 cm / s, which correlates with a stirring time of the reactant of approximately 150 ms.

[0046] A mixture containing water vapor / hexafluoropropene was pre-metered into the substrate immediately before the flow of the Zn and Al precursors into the substrate. The deposition rate was in the range between 35 nm / s and 42 nm / s, resulting in films with a thickness of 850-1000 nm. The sheet's electrical resistance was measured as 50 - 55 ohms / sq. And the specific electrical resistance of the film was 5? 10^-3 ohm-cm.

Example 19 [0047] Borosilicate glass (0.7 mm thick) was heated to 200 ° C (measured on the substrate surface by means of a contact thermocouple) on a nickel heating block. Gas mixture 0.059 mol% Et₂Zn-TMPDA (TMPDA = N, N, N ', N'-tetramethyl-1,3-propanediamine) and 0.0055 mol% Et 2 AlCl in 30 1 / min carrier gas in the form of nitrogen at 180 ° C was given by the original chemical feed for the coating nozzle. In a separate feed, a gas mixture of 0.78 mol% 2-butanol (containing 5 mol% H 2 O) and 0.81 mol% hexafluoropropylene was fed into the inner tube of the coating apparatus at 2.2 1 / min of carrier gas in the form of nitrogen.

[0048] The inner feed tube has been adapted so that the length of the mixing zone is 15 cm. The carrier gas flows in the form of nitrogen have been chosen so that the feed rates on the two inlets are approximately equal. Under these conditions, the face speed at the nozzle outlet of the coating device was approximately 100 cm / s, which correlates with a stirring time of the reactant of approximately 150 ms.

[0049] The deposition rate was 8.5 nm / s, resulting in a 380 nm thick film. The sheet's electrical resistance was measured as 51 ohm / sq and the specific electrical resistance was 2 χ 10^-3 ohm-cm.

Example 20 [0050] Borosilicate glass (0.7 mm thick) was heated to 200 ° C (measured on the surface of the substrate by means of a contact thermocouple) on a nickel heating block. Gas mixture 0.059- mole% Et₂ZirTYlPDA (TMPDA = N, N ', N', N'-tetramethyl-1,3-propanediamine) and 0.011 mole% Et 2 ICI in 30 l / min carrier gas in the form of nitrogen at 180 ° C was given by the primary feed chemical coating nozzle. In a separate feed, a gas mixture of 0.90 mol% 2-butanol (containing 20 mol% H 2 O) and 0.81 mol% hexafluoropropene was fed into the inner tube of the coating apparatus in 2.2 L / min carrier gas in the form of nitrogen.

[0051] The inner feed tube has been adapted so that the length of the mixing zone is 15 cm. The carrier gas flows in the form of nitrogen have been chosen so that the feed rates on the two inlets are approximately equal. Under these conditions, the face speed at the nozzle outlet of the coating device was approximately 100 cm / s, which correlates with a stirring time of the reactant of approximately 150 ms.

[0052] The deposition rate was 9.5 nm / sec, resulting in a film having a thickness of 420 nm. The sheet's electrical resistance was measured as 47 ohm / sq and the specific electrical resistance of the film was 2 χ 10^-3 ^ ohm cm.

[0053] As can be seen from the results of Examples 18-20, the use of water in combination with an admixture containing 1 μl and an admixture containing F (feed 18) provided high coating growth rates, but the surface resistance and film resistivity were slightly higher than in the previous table. 19 and 20. Conversely, Examples 19 and 20 showed lower growth rates and desirable lower resistances of the respective films using an alcohol / water mixture as an oxygen-containing component.

Example 21 [0054] Borosilicate glass (0.7 mm thick) was heated to about 200 ° C on a nickel heating block. A gas mixture of 0.26 mol% Me₂ZmTMPDA (TMPDA = N, N, N ', N'-tetramethyl-1,3-propanediamine) in 10 L / min of carrier gas in the form of nitrogen at 170 ° C was given by primary feeding of the coating nozzle. The dopant precursor, Me2Ga (acac), was added to the primary feed stream through a stainless steel bubbler (16 ° C) using a carrier gas in the form of nitrogen at 30 sccm. In the secondary feed, 1.66 mol% steam was fed in 5 1 / min carrier gas in the form of nitrogen at 170 ° C to the nozzle of the coating apparatus as shown in the figure.

The precursor feeds are connected in a mixing chamber inside the nozzle of the coating device and directed to the surface of the heated glass substrate. The films were grown on stationary medium for 45 seconds.

[0055] The deposition rate was 16 nm / sec, resulting in a film thickness of 730 nm. The specific electrical resistance of the film was measured at 3.1 χ 10^-3 ^ ohm cm. The Hall effect measurement revealed a carrier concentration of 3.5 × 10¹⁹ cm³ and mobility of 5.7 cm²/ V ^ s.

[0056] The dynamic deposition system of Example 21 using water and an admixture of gallium produced a ZnO film at commercially available thicknesses and low resistances of the respective film.

[0057] While the present invention has been described with reference to various specific examples and embodiments, it is to be understood that the invention is not limited thereto and that it may be used in practice in the scope of the following claims.