TUNGSTEN-DOPED INDIUM OXIDE THIN FILM FOR GAMMA RADIATION SENSING, AND METHOD OF SYNTHESIZING THE SAME

Abstract

The present invention relates to radiation sensing. Specifically, the present invention relates to a thin film sensor having tungsten-doped indium oxide (W-INO) thin films as a highly-sensitive material to detect gamma radiation over a dose range of 25 Gy to 200 Gy. The present invention also relates to a method of synthesizing the thin film sensor, and uses thereof.

Specification

Description:FIELD OF THE INVENTION
[0001] The present invention relates to radiation sensing. Specifically, the present invention relates to a thin film sensor having tungsten-doped indium oxide (W-INO) thin films as a highly-sensitive material to detect gamma radiation over a dose range of 25 Gy to 200 Gy. The present invention also relates to a method of synthesizing the thin film sensor, and uses thereof.

BACKGROUND OF THE INVENTION
[0002] Background description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art.
[0003] Gamma radiation, a form of ionizing radiation, is extensively utilized across various fields including medicine, academics, scientific research, and industry. While these applications offer significant benefits, prolonged exposure to gamma radiation poses acute health risks, necessitating stringent monitoring and control measures to safeguard both radiation workers and the general public. The accurate sensing and monitoring of gamma radiation levels are thus critical to minimize exposure and ensure safety. Among the various materials explored for radiation detection, thin film metal oxides have gained attention due to their tunable properties, particularly when doped with specific elements to enhance their sensitivity to gamma radiation.
[0004] Most commercial gamma sensors rely on materials and technologies, such as scintillators, semiconductor materials like cadmium zinc telluride (CZT), or silicon-based detectors, which have more established and reliable performance characteristics for gamma radiation detection. However, thin film metal oxides are a promising technology for gamma sensing, though they are more commonly used in research and development rather than widespread commercial products.
[0005] Among metal oxides, certain compounds like ZnO, TiO2, TeO2 and In2O3 have been explored and used in commercial or pre-commercial gamma sensors. However, metal oxides like ZnO, TiO2, and TeO2 have several drawbacks. ZnO generally has lower electrical conductivity compared to In₂O₃, which can limit its sensitivity and the speed of response for gamma detection applications. R.M. Sahani et al. reported the low sensitivity of the ZnO detector and the need for its enhancement in medical/personal dosimetry. Also, they conclude that a ZnO thick or thin film device is suitable for gamma dosimetry only at the mGy dose level. Moreover, it is not suitable for personal monitoring due to its high fading. TiO₂ has lower electrical conductivity than In₂O₃, which can result in less efficient signal transduction and reduced sensitivity in gamma radiation detection.
[0006] TiO₂ is generally more effective in UV and photocatalytic applications. According to T.K Maity et al., the sensitivity of the material to high radiation exposure is reduced by the substantial structural disorder. Also, it is reported that the stability and sensitivity of TeO2 are higher when mixed with indium oxide. For the mixture compound, the radiation sensitivity is comparatively lesser. T. K. Maity et al. reported that the sensitivity of the real-time gamma radiation dosimeters based on TeO2 thin films with thicknesses ranging from 300 to 1500 nm will be between 1.2 and 37.0 nA/(cm2•μGy).
[0007] In summary, the above materials exhibited lower sensitivity, slower response times, and stability challenges, which can hinder the practical use of these materials in commercial gamma sensors. Achieving the necessary sensitivity and stability with metal oxide thin films for reliable gamma radiation detection is challenging. Also producing high-quality thin films consistently on a commercial scale, and integrating them into devices that can compete with existing sensors, poses technical and economic challenges.
[0008] While thin film metal oxides are not commonly used in commercial gamma sensors today, they hold potential for future applications due to their unique properties, such as transparency, flexibility, and the possibility of miniaturization. Advances in material science, fabrication techniques, and sensor design could eventually lead to their adoption in specialized or next-generation gamma sensing devices. Thin film metal oxides often have high sensitivity to gamma radiation due to their ability to generate electron-hole pairs efficiently when exposed to radiation. Inherently compact and lightweight thin films, make them suitable for applications where space and weight are constraints, such as in portable or wearable devices.
[0009] The fabrication of thin film sensors can be easily scaled up using techniques like spray pyrolysis, sputtering, chemical vapour deposition (CVD), and sol-gel methods. Among these methods spray pyrolysis is especially known for its low cost. Thin film sensors typically exhibit faster response times compared to bulk materials because the reduced dimensionality of the material allows for quicker charge collection. Due to their small size and efficient design, thin film sensors generally require less power to operate, which is beneficial for battery-powered devices.
[0010] Thin films can be deposited on a variety of substrates, including flexible ones, allowing for integration into a wide range of devices and systems. The properties of thin film metal oxides can be tailored by altering the thickness, composition, and doping levels, enabling the design of sensors with specific sensitivity, selectivity, and other desired characteristics. Many metal oxides used in thin film sensors are inherently radiation-hard, meaning they can maintain their functionality in high-radiation environments, making them ideal for long-term monitoring in nuclear facilities, space applications, and other high-radiation environments. Thin films generally require fewer materials than bulk sensors, reducing material costs. Their fabrication methods are also compatible with existing semiconductor manufacturing processes, which can further reduce costs.
[0011] Metal oxides, such as In2O3 are chemically stable and resistant to environmental degradation, ensuring long-term reliability of the sensor in various conditions. These advantages make thin film metal oxide sensors a competitive option for gamma sensing in various applications, from medical imaging and radiation therapy monitoring to environmental radiation detection and space exploration. In₂O₃ thin films generally offer better electrical conductivity, chemical stability, and transparency, along with easier fabrication and integration into devices compared to other thin films like ZnO, TiO₂, and TeO2. We synthesized pristine indium oxide with good sensitivity and sensitivity for gamma radiation enhanced after doping the material with optimized tungsten concentration. These advantages make In₂O₃ more suitable for certain gamma sensing applications, particularly where high sensitivity, fast response, and integration into optical or transparent systems are required. The employed low-cost spray pyrolysis technique for deposition helps in producing high-quality thin film on a commercial scale. Hence, the thin film that was prepared resolves significant issues with metal oxide thin films for applications involving dosimetry and gamma detection.
[0012] Among the various materials explored for radiation detection, thin film metal oxides have gained attention due to their tunable properties, particularly when doped with specific elements to enhance their sensitivity to gamma radiation.
[0013] The present invention addresses the above needs by preparing a thin film sensor comprising tungsten-doped indium oxide (W-INO) thin films as a highly-sensitive material for gamma radiation detection.
[0014] The present invention satisfies the existing needs, as well as others, and generally overcomes the deficiencies found in the prior art.

OBJECTS OF THE INVENTION
[0015] Objects of the present invention are to provide a cost-effective and reliable sensing material for sensing applications.
[0016] An object of the present invention is to provide a sensing material for sensing gamma radiation over a dose range of 25 Gy to 200 Gy.
[0017] Another object of the present invention is to provide a tungsten-doped indium oxide (W-INO) thin films as a highly-sensitive material for sensing gamma radiation over a dose range of 25 Gy to 200 Gy.
[0018] Yet another object of the present invention is to provide a method of synthesizing a tungsten-doped indium oxide (W-INO) thin films.



SUMMARY OF THE INVENTION
[0019] This summary is provided to introduce a selection of concepts in a simplified form that is further described below in the detailed description section. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.
[0020] Aspects of the present invention relate to radiation sensing. Specifically, the present invention relates to a thin film sensor having tungsten-doped indium oxide (W-INO) thin films as a highly-sensitive material to detect gamma radiation over a dose range of 25 Gy to 200 Gy. The present invention also relates to a method of synthesizing the thin film as sensor, and uses thereof.
[0021] In an aspect, the present invention relates to a thin film sensor to detect gamma radiation having a dose range of 25 Gy to 200 Gy comprising: a homogeneous tungsten-doped indium oxide thin film deposited on a substrate,
wherein the indium oxide has a molar concentration of 0.06 to 0.14 M, and
wherein, the indium oxide thin film has 2 atomic% of tungsten doping.
[0022] In an aspect, the thickness of the homogeneous tungsten-doped indium oxide thin film is 525 to 625 nm
[0023] In an aspect, the present invention relates to a method of synthesizing the thin film sensor as disclosed herein, said method comprising:
a) preparing an Indium oxide precursor dissolved in deionized water (Solution A) and a dopant source dissolved in de-ionized water (Solution B), separately for half an hour;
b) adding the dopant source solution (Solution B) to Indium oxide source solution(Solution A), followed by a continuous stirring of mixed solutions in a magnetic stirrer for 15 minutes to get a homogeneous solution;
c) providing a substrate, followed by initial cleaning with a water bath, ultrasonication, and treatment with HCl, IPA (isopropyl alcohol) and acetone, respectively;
d) adding the homogenous solution from step b) to a spray pyrolysis unit; and
e) depositing the homogeneous solution by atomization as a thin film over the substrate under continuous heating at 4500C, followed by cooling the same to room temperature to obtain a homogeneous doped indium oxide thin film.
[0024] In an aspect, the Indium oxide source is indium chloride tetrahydrate (InCl3⋅4H2O).
[0025] In an aspect, the dopant source is ammonium tungsten oxide hydrate.
[0026] In an aspect, the substrate is selected from a glass substrate, FTO substrate, a quartz substrate
[0027] In an aspect, the deposition is effected by using a carrier gas, which is compressed air.
[0028] In an aspect, the ratio of dopant solution and Indium oxide source solution is 0.02:9.98.
[0029] In an aspect, the deposition is effected at a working pressure of 2 atm with a constant nozzle-to-substrate distance of 15 cm and a flow rate of 1ml/min.
[0030] In an aspect, the substrate is continuously heated to a temperature in the range from room temperature to 450° C before the spraying of the homogenous solution onto the substrate.
[0031] Various objects, features, aspects and advantages of the inventive subject matter will become more apparent from the following detailed description of preferred embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS
[0032] FIG. 1 Flowchart illustrating the method of synthesizing and characterising thin film.
[0033] FIG. 2 Schematic representation of spray pyrolysis technique.
[0034] FIG. 3 Current density vs dose plot of 2 % W doped In2O3 thin film at different applied voltages.



DETAILED DESCRIPTION OF THE INVENTION
[0035] The following is a detailed description of embodiments of the disclosure. The embodiments are in such detail as to clearly communicate the disclosure. However, the amount of detail offered is not intended to limit the anticipated variations of embodiments; on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present invention.
[0036] All publications herein are incorporated by reference to the same extent as if each individual publication or patent application were specifically and individually indicated to be incorporated by reference. Where a definition or use of a term in an incorporated reference is inconsistent or contrary to the definition of that term provided herein, the definition of that term provided herein applies and the definition of that term in the reference does not apply.
[0037] Reference throughout this specification to "one embodiment" or "an embodiment" means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, the appearances of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.
[0038] In some embodiments, numbers have been used for quantifying weight percentages, ratios, and so forth, to describe and claim certain embodiments of the invention and are to be understood as being modified in some instances by the term "about." Accordingly, in some embodiments, the numerical parameters set forth in the written description and attached claims are approximations that can vary depending upon the desired properties sought to be obtained by a particular embodiment. In some embodiments, the numerical parameters should be construed in light of the number of reported significant digits and by applying ordinary rounding techniques. Notwithstanding that the numerical ranges and parameters setting forth the broad scope of some embodiments of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as practicable. The numerical values presented in some embodiments of the invention may contain certain errors necessarily resulting from the standard deviation found in their respective testing measurements.
[0039] Various terms as used herein are shown below. To the extent a term used in a claim is not defined below, it should be given the broadest definition persons in the pertinent art have given that term as reflected in printed publications and issued patents at the time of filing.
[0040] As used in the description herein and throughout the claims that follow, the meaning of "a," "an," and "the" includes plural reference unless the context clearly dictates otherwise. Also, as used in the description herein, the meaning of "in" includes "in" and "on" unless the context clearly dictates otherwise.
[0041] Unless the context requires otherwise, throughout the specification which follow, the word "comprise" and variations thereof, such as, "comprises" and "comprising" are to be construed in an open, inclusive sense that is as "including, but not limited to."
[0042] The recitation of ranges of values herein is merely intended to serve as a shorthand method of referring individually to each separate value falling within the range. Unless otherwise indicated herein, each individual value is incorporated into the specification as if it were individually recited herein.
[0043] All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g. "such as") provided with respect to certain embodiments herein is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention otherwise claimed. No language in the specification should be construed as indicating any non-claimed element essential to the practice of the invention.
[0044] Groupings of alternative elements or embodiments of the invention disclosed herein are not to be construed as limitations. Each group member can be referred to and claimed individually or in any combination with other members of the group or other elements found herein. One or more members of a group can be included in, or deleted from, a group for reasons of convenience and/or patentability. When any such inclusion or deletion occurs, the specification is herein deemed to contain the group as modified.
[0045] The description that follows, and the embodiments described therein, is provided by way of illustration of an example, or examples, of particular embodiments of the principles and aspects of the present invention. These examples are provided for the purposes of explanation, and not of limitation, of those principles and of the disclosure.
[0046] It should also be appreciated that the present invention can be implemented in numerous ways, including as a system, a method or a device. In this specification, these implementations, or any other form that the invention may take, may be referred to as processes. In general, the order of the steps of the disclosed processes may be altered within the scope of the invention.
[0047] The headings and abstract of the invention provided herein are for convenience only and do not interpret the scope or meaning of the embodiments.
[0048] The following discussion provides many example embodiments of the inventive subject matter. Although each embodiment represents a single combination of inventive elements, the inventive subject matter is considered to include all possible combinations of the disclosed elements. Thus if one embodiment comprises elements a, b, and c, and a second embodiment comprises elements b and d, then the inventive subject matter is also considered to include other remaining combinations of a, b, c, or d, even if not explicitly disclosed.
[0049] Embodiments of the present invention relate to radiation sensing. Specifically, the present invention relates to a thin film sensor having tungsten-doped indium oxide (W-INO) thin films as a highly-sensitive material to detect gamma radiation over a dose range of 25 Gy to 200 Gy. The present invention also relates to a method of synthesizing the thin film sensor, and uses thereof.
[0050] In an embodiment, the present invention provides a thin film sensor to detect gamma radiation having a dose range of 25 Gy to 200 Gy comprising: a homogeneous tungsten-doped indium oxide thin film deposited on a substrate.
[0051] In an embodiment of the present invention, the indium oxide thin film has 1.5 to 2.5 atomic% of tungsten doping. Preferably 2.0 atomic% of tungsten doping.
[0052] In an embodiment of the present invention, the tungsten-doped indium oxide (W-INO) thin films has a thickness in the range of 525 to 625 nm
[0053] In an embodiment, the present invention provides a method of synthesizing the thin film sensor as disclosed herein, said method comprising:
a) preparing an Indium oxide precursor dissolved in deionized water (Solution A) and a dopant source dissolved in de-ionized water (Solution B), stirring it separately for half an hour;
b) adding the dopant source solution (Solution B) to Indium oxide source solution(Solution A), followed by a continuous stirring of mixed solutions in a magnetic stirrer for 15 minutes to get a homogeneous solution;
c) providing a substrate, followed by initial cleaning with a water bath, ultrasonication, and treatment with HCl, IPA (isopropyl alcohol) and acetone, respectively;
d) adding the homogenous solution from step b) to a spray pyrolysis unit; and
e) depositing the homogeneous solution by atomization as a thin film over the substrate under continuous heating at 4500C, followed by cooling the same to room temperature to obtain a homogeneous doped indium oxide thin film.
[0054] In an embodiment of the present invention, the Indium oxide precursor solution is selected from the group consisting of indium chloride tetrahydrate (InCl3⋅4H2O), indium chloride, indium nitrate and indium sulfate
[0055] In an embodiment of the present invention, the dopant source is selected from the group consisting of ammonium tungsten oxide hydrate, ammonia tungstanate, tungsten hexachloride and tungsten oxide
[0056] In an embodiment of the present invention, the substrate is selected from the group consisting of a glass substrate, FTO substrate and a quartz substrate
[0057] In an embodiment of the present invention, the Indium oxide precursor solution is indium chloride tetrahydrate (InCl3⋅4H2O) mixed with deionized water (Solution A), which is stirred in a magnetic stirrer for half an hour at room temperature.
[0058] In an embodiment of the present invention, the dopant source is ammonium tungsten oxide hydrate dissolved in deionized water (Solution B) which is stirred in a magnetic stirrer for half an hour at room temperature.
In an embodiment of the present invention, the deposition of thin film layer is effected by the spray pyrolysis unit as shown in FIG. 2. Spray pyrolysis is a chemical deposition technique used to produce thin films or powders by spraying a precursor solution onto a heated substrate, where thermal decomposition of the precursor occurs to form a desired material. The precursor solution is prepared by dissolving metal salts, metal-organic compounds, or other suitable chemicals in a solvent (commonly water or alcohol). The solute concentration, solvent type, and precursor selection depend on the material to be deposited. The precursor solution is atomized into fine droplets using a nozzle or spray gun. The fine mist of the precursor solution is sprayed onto a heated substrate. As the droplets approach and touch the hot substrate, the solvent evaporates quickly. The precursor solute undergoes thermal decomposition due to the high temperature, forming the desired material on the substrate surface as a thin film. The reaction by-products (such as gases) are released and carried away, leaving behind a pure thin film of the desired material. The thin film builds up gradually as more droplets impact the substrate. The thickness of the film can be controlled by adjusting the spraying time, the concentration of the precursor solution, the temperature of the substrate, and the flow rate of the spray. The substrate temperature and the choice of precursor are crucial, as they determine the quality and characteristics of the deposited film.
[0059] In an embodiment of the present invention, the deposition is effected by using a carrier gas, which is compressed air.
[0060] In an embodiment of the present invention, the deposition is effected at a working pressure of 2 atm with a constant nozzle-to-substrate distance of 15 cm and a flow rate of 1ml/min.
[0061] In an embodiment of the present invention, the ratio of dopant solution and Indium oxide source solution is 0.015:9.985 to 0.025:9.975. Preferably, the ratio is 0.02:9.98.
[0062] In some embodiments of the present invention, the indium oxide thin film doped with tungsten deposited on a glass substrate using the spray pyrolysis method gives higher sensitivity in the dose range of 25 Gy to 200 Gy than the reported value. [Sudha et al. observed a sensitivity of 1.5-22.4 mA/cm2/Gy with a voltage variation of 2-5 V for INO thin film. Whereas Maity et al. observed a maximum sensitivity of 4.2 mA/cm2 /Gy for the real-time dosimeter fabricated with TeO2 thin film at an applied voltage of 2.4 V]. The low-cost spray pyrolysis method for deposition is ideal for large-scale deposition with a substantially high radiation sensitivity. Hence it can be used for commercial gamma sensors.
[0063] While the foregoing description discloses various embodiments of the disclosure, other and further embodiments of the invention may be devised without departing from the basic scope of the disclosure. The invention is not limited to the described embodiments, versions or examples, which are included to enable a person having ordinary skill in the art to make and use the invention when combined with information and knowledge available to the person having ordinary skill in the art.

EXAMPLES
[0064] The present invention is further explained in the form of following examples. However, it is to be understood that the foregoing examples are merely illustrative and are not to be taken as limitations upon the scope of the invention. Various changes and modifications to the disclosed embodiments will be apparent to those skilled in the art. Such changes and modifications may be made without departing from the scope of the invention.
[0065] Example 1 Synthesizing the tungsten-doped indium oxide thin film
(FIG. 1)
The spray pyrolysis technique was employed to deposit the tungsten-doped indium oxide thin film of molar concentration 0.1 M. The glass substrates (dimension: 2.5cm x 2.5cm) were initially cleaned with a water bath and ultrasonicated, followed by the treatment with HCl, IPA and acetone respectively. The deposition temperature of 4500C was maintained [8]. The precursor solution is made up of indium chloride tetrahydrate (InCl3⋅4H2O) mixed with 10 ml of distilled water (Solution A). This solution is stirred in a magnetic stirrer for half an hour at room temperature. Along with that, a solution of ammonium tungsten oxide hydrate (dopant source) and deionized water is also prepared (Solution B). This solution is also stirred at room temperature for half an hour. To get 2 at% of doping, 0.02 ml of solution B with 9.98 ml of solution A was mixed. It is followed by a continuous stirring of mixed solutions in a magnetic stirrer for 15 minutes to get a homogeneous solution. The obtained solution is sprayed on the preheated glass substrate using a spray pyrolysis unit. The film deposition was carried out at a working pressure of 2 atm with a constant nozzle-to-substrate distance of 15 cm and a flow rate of 1ml/min. Compressed air was used as carrier gas. The experimental setup consists of a conventional spray pyrolysis unit in which the prepared precursor solution is atomized into smaller droplets. The pyrolytic dissociation of these droplets when transferred to a heated substrate yields a homogeneous doped indium oxide thin film. The deposited films were allowed to cool down slowly to room temperature.





Table1: Deposition conditions used for the synthesis of W doped In2O3 (W-INO) thin films by spray pyrolysis
Deposition parameters Conditions used
Precursor InCl3.4H2O + Distilled water
Concentration 0.1M
Substrate Glass
Substrate temperature 4500C
Dopant source Ammonium tungsten oxide hydrate
Doping concentration 2%
Carrier gas Compressed air
Nozzle to substrate distance 15 cm
Flow rate 1ml/min
Working pressure 2 atm

[0066] Example 2: Effectiveness of the tungsten-doped indium oxide thin film
The samples prepared from Example 1 were exposed to γ radiation at a dosage rate of 9.5 KGy/hr using a gamma chamber 5000 with a calibrated 60Co source. The chosen gamma radiation doses are 25 Gy, 50 Gy, 100 Gy and 200 Gy. Electrical characterization was carried out with a Keithley 2450 source metre and the two-probe method was employed to study I-V characteristics.
The term sensitivity is used to quantify the current density variation per unit change in the radiation dose. From the I-V data, the current density is plotted against gamma doses at different voltages (FIG. 3). The slope of the linear portion of the current density vs dose plot gives the material sensitivity. The linear portion of the sensitivity plot is defined as the working region of thin film as a dosimeter.
Table 2: Sensitivity of 2 % W doped In2O3 thin film at different applied voltages.
Applied voltage (V) Sensitivity (mA/cm2/Gy)
1 92.3
2 183.8
3 275.8
4 370.7
5 467.9

ADVANTAGES OF THE PRESNT INVENTION:
[0067] The present invention provides a new metal oxide thin film material with higher sensitivity for gamma sensing.
[0068] The present invention provides a method to obtain optimised W-INO thin film for gamma sensing applications.
[0069] W-INO thin film material of the present invention can also be used for gamma dosimetry.
[0070] The employed low-cost spray pyrolysis technique for deposition in the present invention helps in producing high-quality thin film on a commercial scale.
[0071] Inherently compact and lightweight thin films, make them suitable for applications where space and weight are constraints, such as in portable or wearable devices.
[0072] Due to their small size and efficient design, thin film sensors generally require less power to operate compared to other bulk sensors.
[0073] Thin films generally require fewer materials than bulk sensors, reducing material costs.


, Claims:1. A thin film sensor to detect gamma radiation having a dose range of 25 Gy to 200 Gy comprising: a homogeneous tungsten-doped indium oxide thin film deposited on a substrate,
wherein the indium oxide has a molar concentration of 0.06 to 0.14 M, and
wherein, the indium oxide thin film has 2 atomic% of tungsten doping.
2. The thin film sensor as claimed in claim 1, wherein the thickness of the homogeneous tungsten-doped indium oxide thin film is 525 to 625 nm
3. A method of synthesizing the thin film sensor as claimed in claim 1, said method comprising:
a) preparing an Indium oxide precursor dissolved in deionized water (Solution A) and a dopant source dissolved in de-ionized water (Solution B), stirring it separately for half an hour;
b) adding the dopant source solution (Solution B) to Indium oxide source solution(Solution A), followed by a continuous stirring of mixed solutions in a magnetic stirrer for 15 minutes to get a homogeneous solution;
c) providing a substrate, followed by initial cleaning with a water bath, ultrasonication, and treatment with HCl, IPA (isopropyl alcohol) and acetone, respectively;
d) adding the homogenous solution from step b) to a spray pyrolysis unit; and
e) depositing the homogeneous solution by atomization as a thin film over the substrate under continuous heating at 4500C, followed by cooling the same to room temperature to obtain a homogeneous doped indium oxide thin film.
4. The method as claimed in claims 3, wherein the Indium oxide source is indium chloride tetrahydrate (InCl3⋅4H2O).
5. The method as claimed in claims 3, wherein the dopant source is ammonium tungsten oxide hydrate.
6. The method as claimed in claims 3, wherein the substrate is selected from a glass substrate, an FTO substrate or a quartz substrate
7. The method as claimed in claims 3, wherein the deposition is effected by compressed air.
8. The method as claimed in claims 3, wherein the ratio of dopant solution and Indium oxide source solution is 0.02:9.98.
9. The method as claimed in claims 3, wherein the deposition is effected at a working pressure of 2 atm with a constant nozzle-to-substrate distance of 15 cm and a flow rate of 1ml/min.
10. The method as claimed in claims 3, wherein the substrate is continuously heated from room temperature to 450° C before the spraying of the homogenous solution onto the substrate.

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