156 © 2025 The Author(s). Published by College of Education for Pure Science (Ibn Al-Haitham), University of Baghdad. This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International License Preparing Indium Films and Studying the Effect Oxidation on Their Properties Mohmmad H. Faisal1* and Seham H. Salman2 1,2Department of Physics, College of Education for Pure Science (Ibn Al-Haitham), University of Baghdad, Baghdad, Iraq. *Corresponding Author. Received : 11 May 2024 Accepted: 10 September 2024 Published: 20 April 2025 doi.org/10.30526/38.2.4010 Abstract This research dealt with the preparation and study of the properties of (In2O3) as a film. Indium films were used by the vacuum thermal evaporation technique on a glass base, and then these films were thermally treated at a temperature of 300 in the presence of oxygen for some time (30, 60, 90, 120) minutes to obtain films. Through X-ray diffraction examinations, atomic force microscopy, and ultraviolet radiation, the thin, transparent indium films revealed that the prepared films are cubic crystalline semiconducting materials. The dominant orientation of this crystal is 222, and the energy gap ranges between 2.1 and 2.7 eV. It can be prepared in the form of a film and varies with the oxidation times and depends on the surface roughness and the root mean square of the roughness. The grain size depends on the oxidation period with constant temperature and oxygen pumping rate, as is clear from the atomic force microscope images attached to the research. Keywords: In, In2O3, Thin films, Thermal oxidation, Thermal evaporation. 1. Introduction Indium oxide is considered a semiconductor material (1). It is a transparent oxide (TCO) (2) with an indirect Eg of 3.5 electron volts and an indirect Eg of 2.5 electron volts (3). By evaporating the indium material on glass or silicon bases in a vacuum chamber (4), one can prepare it as a yellow powder or film (5) from the air and then oxidize the membrane using one of the oxidation methods (6), including the rapid thermal oxidation method under normal weather conditions (7). Indium reacts with oxygen to form indium oxide (In2O3) in the following equation: 2In(s) + 3O=In2O3 (8).The presence of additional indium atoms or oxygen holes in indium oxide makes it a donor (n-type donor) (9). The In2O3 film is used as an anti- reflective window layer on the surfaces of solar cells. It is a regular and transparent film (about 80% in the visible region (0.4-0.9 µm)). It has high reflectivity in the IR region and is, therefore, a heat-reflecting window (9-12). It is also a polycrystalline membrane with a cubic structure and has a lattice constant of 10.118 Ǻ) according to the American standard (ASTM) (13). Indium(III) oxide is insoluble in both water and alkalis (14), but it can dissolve in acids (15), https://creativecommons.org/licenses/by/4.0/ https://creativecommons.org/licenses/by/4.0/ https://orcid.org/0009-0006-2102-9672 mailto:mohammed.harej2204m@ihcoedu.uobaghdad.edu.iq https://orcid.org/0000-0003-4495-2831 mailto:seham.h.s@ihcoedu.uobaghdad.edu.iq IHJPAS. 2025,38(2) 157 transparent reflectors of hot mirrors, as a transparent conductive paint in combination with tin dioxide (SnO2) (16), and it is also used in integrated circuits (as a resistive element)(17). 2. Materials and Methods Indium oxide In2O3 thin films were fabricated using the thermal oxidation process. The initial stage was the deposition of tiny layers of indium metal via vacuum thermal evaporation. The process of evaporation was conducted. in a state of low pressure of order of 2*10-5mbar. The deposit rate is approximately 1.33±0.2 nm/sec. , the distance (18 cm) between the Mo boat and the substrate. The indium thin films of thickness 400 nm (total surface area 2 × 2 mm). The second phase, which involved the thermal oxidation of a thin layer of In, was carried out. (30, 60, 90, and 120) min. at 300 °C in the presence of O2. By employing a flat electric heater to provide heat to the substrate. The films were analyzed for crystallinity and the presence of crystalline phases using X-ray diffraction (XRD) with a CuKα X-ray diffractometer. (Shimadzu Japan -XRD600). The measurement of the absorbance and transmittance of the formed thin film was conducted utilizing. The UV-visible 1800 spectra photometer measures wavelengths within a specific range. spans from 200 to 1100 nm. With a resolution of more than 300 dpi and less than 600 dpi and without borders, with the capital first letter of axis titles and write its unit. Tables and Figures are placed in the results in the sequence mentioned, not at the end of the manuscript. 3. Results and Discussion 3.1. The Analysis Using X-Ray Diffraction (XRD) Figure 1 as seen in the X-ray diffraction. The rhombohedral structure of thin film polycrystalline material as in. Diffraction data relates to the [011]'s existence. Diffraction peaks are found in crystalline materials. The evaporation of the metallic material occurred at an angle of 32.9822° concerning 2θ. Following oxidation in Figure 2, the films (In2O3) exhibited a polycrystalline cubic structure. The videos have notable peaks at 21.448º, 30.515º, and 35.38º in the pacified order, matching the (112), (222), and (004) planes. These peaks match or are equal. to cubic. The JCPDS card 98-064-0179 identifies the chemical as indium oxide. The (222) line's preferred orientation. The result corresponds with that described by (18-20). From the x-ray, it is possible to see that the intensity increases with increasing oxidation time, indicating enhanced crystalline structure and crystalline size modification. Figure 1. X-ray diffraction of the In film before oxidation. IHJPAS. 2025,38(2) 158 Figure 2. X-ray diffraction of the In2O3 film at different oxidation times. Table 1. It is clear. X-ray diffraction traces for In2O3 thin film oxidation . The (222) line's orientation in the XRD peaks was To ascertain the structural properties, including variables like the crystalline C.s., the dislocation density, and the mean lattice strain ε Considering the dislocation density as well as the quantity of crystallites in each area, the following relationships need to be considered (21-27).The information is included in Table 2. C.s = 0.9λ / (βCosθ) (1) δ =1/ (C.s) 2 (2) ε = β Cosθ/ 4 (3) No = t/(C.s)3 (4) where the breadth at half its high intensity is represented by β. The thin layer's thickness is represented by the variable "t". 0 200 400 600 800 1000 1200 1400 1600 1800 10 20 30 40 50 60 70 80 In te n si ty ( u .a ) 2Ɵ(degree) In2O3 at 90 (400) (222) (112) 0 200 400 600 800 1000 1200 1400 10 20 30 40 50 60 70 80 In te n si ty ( u .a ) 2Ɵ(degree) In2O3 at 120 (011)In (222) (112) JCPDS card No. Oxidation Time(min) Temp. 2θ Exp. 2θ ASTM d-Exp. d ASTM Hkl 98-064-0179 30 300 30.5672 30.515 2.92226 2.92717 222 60 30.5596 2.92297 90 30.4452 2.9337 120 30.4745 2.93094 IHJPAS. 2025,38(2) 159 Table 2. lists the relevant characteristics, which include the number of crystallites, macrostrain, density of dislocations, and size of the crystallites. Which Oxidation at various moments. 3.2. Surface Morphology One of the most applicable methods for surface morphology is Atomic Force Microscopy (AFM). It is well known that the surface morphology of films affects their properties, which is crucial for applications like gas sensing. It shows the presence of homogenous grains throughout the film. are shown in Table 3. As a result, it is crucial to look into the surface morphology of films because increasing surface roughness of the films. The appearance of the surface of the In2O3 Figure 3. AFM for In2O3 at 30 min. Oxidation time (min). 2ϴ β (deg) β (rad) C.s(nm) δ (nm)-2 ε 𝑁𝑜 (nm)-2 30 30.5672 0.1943 0.003389 44.27479 0.00051 0.000817 0.004609 60 30.5596 0.2125 0.003707 40.48206 0.00061 0.000894 0.006029 90 30.4452 0.1897 0.003309 45.33524 0.00048 0.000798 0.004293 120 30.4745 0.2483 0.004331 34.63832 0.00083 0.001045 0.009625 IHJPAS. 2025,38(2) 160 Figure 4. AFM for In2O3 at 60 min. Figure 5. AFM for In2O3 at 90 min. IHJPAS. 2025,38(2) 161 Figure 6. AFM for In2O3 at 120 min. Table 3. Mean diameter, roughness and root mean square at different times. oxidation times (min) Mean diameter (nm) Roughness(nm) Root-mean-square (nm) 30 315.9 68.62 86.18 60 439.4 77.32 98.26 90 299.0 76.82 97.79 120 362.1 78.43 96.67 From the table above, we find that the surface roughness rate is better when the feeding duration is 30 minutes, as well as the square root of the roughness. As for the size of the particles or the diameter of the lung, we obtain a larger amount when the oxidation time is 60 minutes. 3. 3.Optical Characteristics Figure 3 shows the transmittance and absorbance spectra, which were quantified to examine the optical properties. According to our research, the film shows excellent transmission at long wavelengths and poor transmission at short wavelengths. We notice from the figure that if the oxidation time is short, the transmission value is lower and increases as it increases. This means that absorption reaches its peak at a low value of wavelength, that is, within the beginning of the visible light. It is possible to benefit from In2O3In thin films in the manufacture of solar cells and photodiodes due to their high absorption. IHJPAS. 2025,38(2) 162 Figure 7. Absorption and transmittance of In2O3 at different oxidation times. Figure 8.The variation (α) with h𝝼 for In2O3 thin films. Absorption coefficient determined by equation (5)(28): α =2.303A/t (5) The equation(6) was used to find the extinction coefficient (K) of In2O3 (29) 𝐾 = 𝛼𝜆 /4𝜋 (6) Figure 9. Illustrates the relationship between the extinction coefficient and Energy for In2O3 thin films. IHJPAS. 2025,38(2) 163 Figure 10. Plot of (αhυ) 2 versus (hυ) for In2O3 thin films. The energy gap was computed via Tauck's.(29-32) (αhv)=B(h𝝼-Eg)n (7) Here is how the equation is defined: The constant denoted by the symbol (B) and the exponent represented by the symbol (n) are established by the material's particular quantum selection criteria.Plot the relationship between hν and (α hv)2 to find the direct band gap. Figure 6 illustrates this. Table 3 shows that the optical band gap energy of the film was determined to be 2.1, 2.15, 2.5, and 2. 7 eV. The energy gap increases with increasing oxidation time; this is due to a greater width of the tails of the localized states, which may not be considered suitable for dangling bonds during the process of growth and crystal formation, as shown in the table below Table 3. Table 4. Bandgap variation of In2O3 thin films with different oxidation times. oxidation times (min) Eg(eV) 30 2.1 60 2.15 90 2.5 120 2.7 4. Conclusion Indium oxide thin films with different time oxidation have been successfully deposited after oxidation by the evaporation technique on glass substrates. The effect of oxidation time on properties was investigated. (In2O3) exhibited a polycrystalline cubic structure. These peaks match or are equal. The (222) line's preferred orientation. We find that the surface roughness rate is better when the feeding duration is 30 minutes. The optical band gap energy of the film was determined to be 2.1, 2.15, 2.5, and 2. 7 eV. The energy gap increases with increasing oxidation time. Acknowledgment We thank the Thin Film Lab., Department of Physics, College of Education for Pure Science (Ibn Al-Haitham), University of Baghdad. IHJPAS. 2025,38(2) 164 Conflict of Interest The authors declare that they have no conflicts of interest. Funding None. References 1. Kim J, Shrestha S, Souri M, Connell JG, Park S, Seo A. High-temperature optical properties of indium tin oxide thin-films. 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