Synthesis, Optical Energy Gap and Gas Sensing Properties of TiO2 Doped Cr2O3 Thin Films

Nihad K. Ali; Ikhlas H. Sallal

doi:10.30526/39.1.4258

Authors

Nihad K. Ali Department of Physics, College of Education for Pure Science /Ibn Al-Haitham, Baghdad University, Baghdad, Iraq https://orcid.org/0009-0007-0920-5626
Ikhlas H. Sallal Department of Physics, College of Education for Pure Science /Ibn Al-Haitham, Baghdad University, Baghdad, Iraq https://orcid.org/0000-0002-3241-8984

DOI:

https://doi.org/10.30526/39.1.4258

Keywords:

Thin films, Optical, Gas sensing, Cr2O3:TiO2, Laser ablation

Abstract

Thin films of Titanium dioxide (TiO2) doped Chromium oxide (Cr2O3) with a thickness of nm and a doping ratio of (0.2, 0.4, 0.6, 0.8)% employed on glass and n-type porous silicon substrates by using Pulsed laser ablation technique. A Cr2O3: TiO2/PSi heterojunction for a gas sensor device was synthesized with Nd: YAG laser with 1064nm wavelength with 500 pulses of laser energy 600mJ. The effect of the dopant concentration ratios on absorption coefficient ,optical energy gap and gas sensing properties such as sensitivity, responsivity and recovery times in the presence of 400ppm concentration of H₂S gas, were studied and discussed. The doped samples showed increased absorption coefficient values with higher doping concentrations. The optical band gap ranged from 3.95 eV-3.71 eV for the pure and TiO2 doped Cr2O3 thin films. The optimum sensitivity was (166.24%) when the doping ratio of TiO2 was 0.6% when exposed to an H2S-reduced gas at an operating temperature of 100^οC.

Author Biographies

Nihad K. Ali, Department of Physics, College of Education for Pure Science /Ibn Al-Haitham, Baghdad University, Baghdad, Iraq

Department of Physics, College of Education for Pure Science /Ibn Al-Haitham, Baghdad University, Baghdad, Iraq
Ikhlas H. Sallal, Department of Physics, College of Education for Pure Science /Ibn Al-Haitham, Baghdad University, Baghdad, Iraq

Department of Physics, College of Education for Pure Science /Ibn Al-Haitham, Baghdad University, Baghdad, Iraq

References

1. Abdul Kareem SM, Jassim IK, Suhail MH. Cr2O3: TiO2 nanostructure thin film prepared by pulsed laser deposition technique as NO2 gas sensor. Baghdad Sci J. 2020;17(1 Suppl March):329-35. https://dx.doi.org/10.21123/bsj.2020.17.1(Suppl.).0329

2. Hassan TB, Mohammed GH. FTIR and optical properties of NiO doped Cr2O3 nanoparticles synthesis by hydrothermal method. Al-Mustansiriyah J Sci. 2018;29(1):168-73. http://doi.org/10.23851/mjs.v29i1.278

3. Suhail MH, Adehmash IK, Abdul Kareem SM, Tahir DA, Abdullah OG. Construction of Cr2O3:ZnO nanostructured thin film prepared by pulsed laser deposition technique for NO2 gas sensor. Trans Electr Electron Mater. 2020. https://doi.org/10.1007/s42341-020-00182-3

4. Singh J, Verma V, Kumar R, Kumar R. Structural, optical and electrical characterization of epitaxial Cr2O3 thin film deposited by PLD. Mater Res Express. 2019. https://doi.org/10.1088/2053-1591/ab3543

5. Salman SH, Shihab AA, Elttayef AK. Design and construction of nanostructure TiO2 thin film gas sensor prepared by R.F magnetron sputtering technique. Energy Procedia. 2019;157:283-9. https://doi.org/10.1016/j.egypro.2018.11.192

6. Liang Y, Ding M, Yang Y, Xu K, Luo X, Yu T, Liang Y, Ding M, Yang Y, Xu K, Luo X, Yu T, Zhang, W., Liu W. & Yuan C.. Highly dispersed Pt nanoparticles on hierarchical titania nanoflowers with {010} facets for gas sensing and photocatalysis. J Mater Sci. 2019;54:6826-40. https://doi.org/10.1007/s10853-019-03379-x

7. Salman SH, Hassan NA, Ahmed GS. Copper telluride thin films for gas sensing applications. Chalcogenide Lett. 2022;19(2):125-30. https://doi.org/10.15251/CL.2022.192.125

8. Abbas IA, Hazaa SQ, Salman SH. Employment of titanium dioxide thin film on NO2 gas sensing. J Phys Conf Ser. 2021;1879(3):032061. https://doi.org/10.1088/1742-6596/1879/3/032061

9. Alrazak AHA, Salman SH, Abbas IA, Mustafa MH, Ali HM, Abbas SA. Influence of doping with silver nanoparticles on the molybdenum trioxide gas sensor prepared by spray pyrolysis. Dig J Nanomater Biostruct. 2025;20(1):191-9. https://doi.org/10.15251/DJNB.2025.201.191

10. Abdul Kareem I, Oleiwi HF. Enhancing gas sensing performance of TiO2-ZnO nanostructures: effect of ZnO concentration. Ibn Al-Haitham J Pure Appl Sci. 2023;36(4):137-46. https://doi.org/10.30526/36.4.3173

11. Song Z, Yan J. Unveiling the doping effect of sub-4 nm ultrathin SnO2 quantum wires on gas sensors. Chem Mater. 2023;35(18):7750-60. https://doi.org/10.1021/acs.chemmater.3c01609

12. Wang L, Yao X, Yuan S , Gao Y., Zhang R, Yu X , Tu ST and Chen S. Ultra-high performance humidity sensor enabled by a self-assembled CuO/Ti3C2TX MXene. RSC Adv. 2023;13(9):6264-73. https://doi.org/10.1039/D2RA06903B

13. Hermawan A ,Zhang B ,Taufik A ,Asakura Y ,Hasegawa T,Zhu J ,Shi P and Yin S CuO nanoparticles/Ti3C2Tx mxene hybrid nanocomposites for detection of toluene gas. ACS Appl Nano Mater. 2020;3(5):4755-66. https://doi.org/10.1021/acsanm.0c00749

14. Salman SH, Jahil SS, Hassan NA, Abbas SA, Jasim KA. Ammonia gas sensing using porous silicon. J Phys Conf Ser. 2024;2857(1):012051. https://doi.org/10.1088/1742-6596/2857/1/012051

15. Dawood NS, Zayer MQ, Jawad MF. Preparation and characteristics study of porous silicon for vacuum sensor application. Karbala Int J Mod Sci. 2022;8(1):11. https://doi.org/10.33640/2405-609X.3209

16. Hadi HA, Ismail RA, Almashhadani NJ. Preparation and characteristics study of polystyrene/porous silicon photodetector prepared by electrochemical etching. J Inorg Organomet Polym Mater. 2019;29:1100-10. https://doi.org/10.1007/s10904-019-01072-9

17. Ibrahim FT, Abdughani SE. Effect of lasing energy on the structure and optical and gas sensing properties of chromium oxide thin films. Indian J Phys.2019. https://doi.org/10.1007/s12648-019-01492-w

18. Saruhan B, Lontio Fomekong R, Nahirniak S. Review: Influences of semiconductor metal oxide properties on gas sensing characteristics. Front Sens. 2021;2:657931. https://doi.org/10.3389/fsens.2021.657931

19. Pasupuleti K S. Pham TMT, Abraham B M, Thomas A M ,Vidyasagar D, Bak NH, Kampara R K, Yoon SG, Kim YH & Kim M D . Room temperature ultrasensitive ppb-level H2S SAW gas sensor based on hybrid CuO@V2C MXene van der Waals heterostructure. Adv Compos Hybrid Mater. 2025;8:132. https://doi.org/10.1007/s42114-024-01194-w

20. Wang H, Luo Y, Liu B, Gao L, Duan G. CuO nanoparticle loaded ZnO hierarchical heterostructure to boost H2S sensing with fast recovery. Sens Actuators B Chem. 2021;338:129806. https://doi.org/10.1016/j.snb.2021.129806

21. He H , Zhao C , Xu J, Qu K Jiang Z. Gao Z and Song YY. Exploiting free-standing p-CuO/n-TiO2 nanochannels as a flexible gas sensor with high sensitivity for H2S at room temperature. ACS Sens. 2021;6(9):3387-97. https://doi.org/10.1021/acssensors.1c01256

22. Zhang B, Shang F, Shi X, Yao R, Wei F, Hou X. Polyaniline/CuO nanoparticle composites for use in selective H2S sensors. ACS Appl Nano Mater. 2023;6(19):18413-25. https://doi.org/10.1021/acsanm.3c03732

23. Makarov GN. Laser applications in nanotechnology: nanofabrication using laser ablation and laser nanolithography. Phys Usp. 2013;56(7):643-82. http://dx.doi.org/10.3367/UFNe.0183.201307a.0673

24. Sze SM. Physics of semiconductor devices. 2nd ed. New York: John Wiley and Sons; 1981

25. Zahra S, Syed WAA, Rafiq N, Shah WH, Iqbal Z. On structural, optical, and electrical properties of chromium oxide Cr2O3 thin film for applications. Prot Met Phys Chem Surf. 2021;57(2):321-8. https://doi.org/10.1134/S2070205121010238

26. Hones P, Diserens M, Lévy F. Characterization of sputter-deposited chromium oxide thin films. Surf Coat Technol. 1999;120-121:277-83. https://doi.org/10.1016/S0257-8972(99)00384-9

27. Nguyen TA, Moharana S, Sahu BB, Satpathy SK. Electric and electronic applications of metal oxides. 1st ed. Cambridge (MA): Elsevier; 2025. https://doi.org/10.1016/C2023-0-50311-8

28. Xavier AM, Jacob DI, Surender S, Saravana kumaar MSS, Elangovan P. Structural, optical and electronic properties of copper doped TiO2: combined experimental and DFT study. Inorg Chem Commun. 2022;146:110168. https://doi.org/10.1016/j.inoche.2022.110168

29. Wu J, Luo Y, Qin Z. Composite-modified nano-TiO2 for the degradation of automobile exhaust in tunnels. Constr Build Mater. 2023;408:133805. https://doi.org/10.1016/j.conbuildmat.2023.133805

30. Wang L, Xu S, Yang J, Huang H, Huo Z, Li J. Recent progress in solar-blind photodetectors based on ultrawide bandgap semiconductors. ACS Omega. 2024;9(24):25429-47. https://doi.org/10.1021/acsomega.4c02897

31. Tilley RJD. Defects in solids. Hoboken (NJ): John Wiley & Sons, Inc.; 2008. ISBN: 978-0-470-07794-8. https://doi.org/10.1002/9780470380758

32. Dutta T, Noushin T, Tabassum S, Mishra SK. Road map of semiconductor metal-oxide-based sensors: a review. Sensors. 2023;23(15):6849. https://doi.org/10.3390/s23156849