本實驗以晶圓尺寸合成修飾有金與銅氧化物的氧化鋅奈米複合材料，目的在於批量生產具氣體感測試片；此外也使用製作的試片進行臭氧氣體感測，並與二氧化氮進行比較，以探討修飾物對氣體感測結果的影響。
實驗首先在鍍有電極圖案的四吋晶圓上，使用低溫水熱法成長氧化鋅奈米柱並進行退火，接著利用光沉積法將金奈米粒子及銅氧化物修飾於氧化鋅奈米柱上，再將合成的複合材料製作成氣體感測晶片。
藉由掃描式電子顯微鏡觀察材料表面形貌，氧化鋅為直徑約100 nm的六角柱；在進行光沉積法修飾後，金／氧化鋅在奈米柱表面出現粗糙的顆粒狀結構，銅氧化物／氧化鋅的表面分散分布著數百奈米大小的顆粒，銅氧化物／金／氧化鋅在奈米柱頂端包覆著銅氧化物顆粒，金／銅氧化物／氧化鋅在銅氧化物顆粒上出現細小的顆粒。
使用以上材料分別在100 ppb的臭氧及二氧化氮環境中進行紫外光活化的氣體感測。結果顯示退火會大幅降低氧化鋅試片對臭氧及二氧化氮的響應，在進行修飾後，金／氧化鋅在臭氧及二氧化氮的響應有相似幅度的提升，銅氧化物／氧化鋅對於臭氧響應僅有少量的提升，對二氧化氮響應則有大幅的提升；銅氧化物／金／氧化鋅在二氧化氮響應上同樣有高於臭氧響應的提升，金／銅氧化物／氧化鋅則展現出提高的臭氧響應，以及下降的二氧化氮響應。
本實驗將過去少量合成材料的方式擴展為在四寸晶圓上的合成，成功進行感測試片的大面積合成；也在臭氧及二氧化氮的氣體感測結果中，觀察到修飾物除了造成響應的提升，也會對選擇性造成影響。

In this work, the nanocomposite materials based on Au and CuxO modified ZnO nanorods were synthesized in 4-inch wafer scale for the batch production of gas sensing chips. We used the synthesized sensing chips to do ozone and nitrogen dioxide gas sensing, to discuss the effects of the additives on sensing properties.
Zinc oxide nanorods were grown by a hydrothermal method on a 4-inch wafer with electrode patterns. After the annealing process, Au and CuxO were added on the surface of zinc oxide nanorods by photodeposition processes.
The morphologies of the materials were observed by the scanning electron microscope. The results showed that ZnO were hexagonal rods with a diameter around 100 nm. After the photodeposition processes, Au/ZnO showed rough structure on the nanorods and CuxO/ZnO showed randomly distributed submicron particles. CuxO/Au/ZnO showed particles on the tips of the nanorods and Au/CuxO/ZnO showed small particles on the CuxO particles.
The gas sensing experiments with 100 ppb ozone and nitrogen dioxide were done under UV activation mode. The results showed that annealing process reduced the response of ZnO. Au/ZnO* showed similarly increased responses for both ozone and nitrogen dioxide. CuxO/ZnO* showed a higher increase in the response for nitrogen dioxide than the increase for ozone. CuxO/Au/ZnO* also showed a large increase in the response for nitrogen dioxide. Au/CuxO/ZnO* showed a increased response for ozone while the response for nitrogen dioxide was decreased.
In conclusion, we successfully synthesized ZnO nanocomposites on 4-inch wafers for the batch production of gas sensing chips. The results of ozone and nitrogen dioxide gas sensing showed the additives can increase the sensing responses and cause the change in selectivity to different gases.

Bochenkov, V.; Sergeev, G., Sensitivity, selectivity, and stability of gas-sensitive metal-oxide nanostructures. Metal Oxide Nanostructures and Their Applications 2010, 3, 31-52.
2. Neri, G., First fifty years of chemoresistive gas sensors. Chemosensors 2015, 3 (1), 1-20.
3. Liu, X.; Cheng, S.; Liu, H.; Hu, S.; Zhang, D.; Ning, H., A survey on gas sensing technology. Sensors 2012, 12 (7), 9635-9665.
4. Feng, S.; Farha, F.; Li, Q.; Wan, Y.; Xu, Y.; Zhang, T.; Ning, H., Review on smart gas sensing technology. Sensors 2019, 19 (17), 3760.
5. Kim, H. J.; Lee, J. H., Highly sensitive and selective gas sensors using p-type oxide semiconductors: Overview. Sensors and Actuators B: Chemical 2014, 192, 607-627.
6. Wang, C.; Yin, L.; Zhang, L.; Xiang, D.; Gao, R., Metal oxide gas sensors: sensitivity and influencing factors. Sensors 2010, 10 (3), 2088-2106.
7. Li, Z. J.; Li, H.; Wu, Z. L.; Wang, M. K.; Luo, J. T.; Torun, H. D.; Hu, P. A.; Yang, C.; Grundmann, M.; Liu, X. T.; Fu, Y. Q., Advances in designs and mechanisms of semiconducting metal oxide nanostructures for high-precision gas sensors operated at room temperature. Materials Horizons 2019, 6 (3), 470-506.
8. Dey, A., Semiconductor metal oxide gas sensors: A review. Materials Science and Engineering: B 2018, 229, 206-217.
9. Franke, M. E.; Koplin, T. J.; Simon, U., Metal and metal oxide nanoparticles in chemiresistors: does the nanoscale matter? Small 2006, 2 (1), 36-50.
10. Karnati, P.; Akbar, S.; Morris, P. A., Conduction mechanisms in one dimensional core-shell nanostructures for gas sensing: A review. Sensors and Actuators B: Chemical 2019, 295, 127-143.
11. Zhu, L.; Zeng, W., Room-temperature gas sensing of ZnO-based gas sensor: A review. Sensors and Actuators A: Physical 2017, 267, 242-261.
12. Christoulakis, S.; Suchea, M.; Koudoumas, E.; Katharakis, M.; Katsarakis, N.; Kiriakidis, G., Thickness influence on surface morphology and ozone sensing properties of nanostructured ZnO transparent thin films grown by PLD. Applied Surface Science 2006, 252 (15), 5351-5354.
13. Fan, S. W.; Srivastava, A. K.; Dravid, V. P., UV-activated room-temperature gas sensing mechanism of polycrystalline ZnO. Applied Physics Letters 2009, 95 (14), 142106.
14. Bernardini, S.; Fiorido, T.; Aguir, K.; Margeat, O.; Ackermann, J.; Videlot-Ackermann, C., UV-enhanced Ozone Sensing Response of Al-doped Zinc Oxide Nanocrystals at Room Temperature. Materials Today: Proceedings 2019, 6, 310-313.
15. da Silva, L. F.; M’peko, J.-C.; Catto, A. C.; Bernardini, S.; Mastelaro, V. R.; Aguir, K.; Ribeiro, C.; Longo, E., UV-enhanced ozone gas sensing response of ZnO-SnO2 heterojunctions at room temperature. Sensors and Actuators B: Chemical 2017, 240, 573-579.
16. Catto, A. C.; da Silva, L. F.; Ribeiro, C.; Bernardini, S.; Aguir, K.; Longo, E.; Mastelaro, V. R., An easy method of preparing ozone gas sensors based on ZnO nanorods. RSC Advances 2015, 5 (25), 19528-19533.
17. Bai, S.; Ma, Y.; Shu, X.; Sun, J.; Feng, Y.; Luo, R.; Li, D.; Chen, A., Doping metal elements of WO3 for enhancement of NO2-sensing performance at room temperature. Industrial & Engineering Chemistry Research 2017, 56 (10), 2616-2623.
18. Degler, D.; Weimar, U.; Barsan, N., Current understanding of the fundamental mechanisms of doped and loaded semiconducting metal-oxide-based gas sensing materials. ACS Sensors 2019, 4 (9), 2228-2249.
19. Al-Hashem, M.; Akbar, S.; Morris, P., Role of oxygen vacancies in nanostructured metal-oxide gas sensors: a review. Sensors and Actuators B: Chemical 2019, 301, 126845.
20. Ahn, M.-W.; Park, K.-S.; Heo, J.-H.; Park, J.-G.; Kim, D.-W.; Choi, K. J.; Lee, J.-H.; Hong, S.-H., Gas sensing properties of defect-controlled ZnO-nanowire gas sensor. Applied Physics Letters 2008, 93 (26), 263103.
21. Xia, H.; Wang, Y.; Kong, F.; Wang, S.; Zhu, B.; Guo, X.; Zhang, J.; Wang, Y.; Wu, S., Au-doped WO3-based sensor for NO2 detection at low operating temperature. Sensors and Actuators B: Chemical 2008, 134 (1), 133-139.
22. Miller, D. R.; Akbar, S. A.; Morris, P. A., Nanoscale metal oxide-based heterojunctions for gas sensing: a review. Sensors and Actuators B: Chemical 2014, 204, 250-272.
23. Morrison, S. R., Selectivity in semiconductor gas sensors. Sensors and Actuators 1987, 12 (4), 425-440.
24. Frietsch, M.; Zudock, F.; Goschnick, J.; Bruns, M., CuO catalytic membrane as selectivity trimmer for metal oxide gas sensors. Sensors and Actuators B: Chemical 2000, 65 (1-3), 379-381.
25. Joshi, R. K.; Hu, Q.; Alvi, F.; Joshi, N.; Kumar, A., Au decorated zinc oxide nanowires for CO sensing. The Journal of Physical Chemistry C 2009, 113 (36), 16199-16202.
26. Rai, P.; Majhi, S. M.; Yu, Y. T.; Lee, J. H., Noble metal@metal oxide semiconductor core@shell nano-architectures as a new platform for gas sensor applications. RSC Advances 2015, 5 (93), 76229-76248.
27. DeMeo, D.; MacNaughton, S.; Sonkusale, S.; Vandervelde, T., Electrodeposited copper oxide and zinc oxide core-shell nanowire photovoltaic cells. Nanowires—Implementations and Applications; Hashim, A., Ed.; InTech: Rijeka, Croatia 2011, 141-156.
28. Bendahan, M.; Boulmani, R.; Seguin, J. L.; Aguir, K., Characterization of ozone sensors based on WO3 reactively sputtered films: influence of O2 concentration in the sputtering gas, and working temperature. Sensors and Actuators B: Chemical 2004, 100 (3), 320-324.
29. Onofre, Y. J.; Catto, A. C.; Bernardini, S.; Fiorido, T.; Aguir, K.; Longo, E.; Mastelaro, V. R.; da Silva, L. F.; de Godoy, M. P. F., Highly selective ozone gas sensor based on nanocrystalline Zn0.95Co0.05O thin film obtained via spray pyrolysis technique. Applied Surface Science 2019, 478, 347-354.
30. Ivanovskaya, M.; Gurlo, A.; Bogdanov, P., Mechanism of O3 and NO2 detection and selectivity of In2O3 sensors. Sensors and Actuators B: Chemical 2001, 77 (1), 264-267.
31. Barreca, D.; Bekermann, D.; Comini, E.; Devi, A.; Fischer, R. A.; Gasparotto, A.; Maccato, C.; Sada, C.; Sberveglieri, G.; Tondello, E., Urchin-like ZnO nanorod arrays for gas sensing applications. CrystEngComm 2010, 12 (11), 3419-3421.
32. da Silva, L. F.; M’Peko, J. C.; Catto, A. C.; Bernardini, S.; Mastelaro, V. R.; Aguir, K.; Ribeiro, C.; Longo, E., UV-enhanced ozone gas sensing response of ZnO-SnO2 heterojunctions at room temperature. Sensors and Actuators B: Chemical 2017, 240, 573-579.
33. Belaqziz, M.; Amjoud, M. b.; Gaddari, A.; Rhouta, B.; Mezzane, D., Enhanced room temperature ozone response of SnO2 thin film sensor. Superlattices and Microstructures 2014, 71, 185-189.
34. Klingshirn, C. F.; Waag, A.; Hoffmann, A.; Geurts, J., Zinc oxide: from fundamental properties towards novel applications. Springer Science & Business Media: 2010; Vol. 120.
35. Wang, Z. L., Zinc oxide nanostructures: growth, properties and applications. Journal of Physics: Condensed Matter 2004, 16 (25), R829.
36. Zhang, Y.; Ram, M. K.; Stefanakos, E. K.; Goswami, D. Y., Synthesis, characterization, and applications of ZnO nanowires. Journal of Nanomaterials 2012, 2012, 624520.
37. Zhang, X.; Suemune, I.; Kumano, H.; Wang, J.; Huang, S., Surface-emitting stimulated emission in high-quality ZnO thin films. Journal of Applied Physics 2004, 96 (7), 3733-3736.
38. Schmidt-Mende, L.; MacManus-Driscoll, J. L., ZnO - nanostructures, defects, and devices. Materials Today 2007, 10 (5), 40-48.
39. Zhang, S. B.; Wei, S. H.; Zunger, A., Intrinsic n-type versus p-type doping asymmetry and the defect physics of ZnO. Physical Review B 2001, 63 (7), 075205.
40. Gadallah, A. S.; El-Nahass, M. M., Structural, Optical Constants and Photoluminescence of ZnO Thin Films Grown by Sol-Gel Spin Coating. Advances in Condensed Matter Physics 2013, 2013, 234546.
41. Srikant, V.; Clarke, D. R., On the optical band gap of zinc oxide. Journal of Applied Physics 1998, 83 (10), 5447-5451.
42. Vanheusden, K.; Warren, W.; Seager, C.; Tallant, D.; Voigt, J.; Gnade, B., Mechanisms behind green photoluminescence in ZnO phosphor powders. Journal of Applied Physics 1996, 79 (10), 7983-7990.
43. Li, Y.; Meng, G. W.; Zhang, L. D.; Phillipp, F., Ordered semiconductor ZnO nanowire arrays and their photoluminescence properties. Applied Physics Letters 2000, 76 (15), 2011-2013.
44. Sun, Y.; Fuge, G. M.; Ashfold, M. N., Growth of aligned ZnO nanorod arrays by catalyst-free pulsed laser deposition methods. Chemical Physics Letters 2004, 396 (1-3), 21-26.
45. Hartanto, A.; Ning, X.; Nakata, Y.; Okada, T., Growth mechanism of ZnO nanorods from nanoparticles formed in a laser ablation plume. Applied Physics A 2004, 78 (3), 299-301.
46. Sun, X.; Kwok, H. S., Optical properties of epitaxially grown zinc oxide films on sapphire by pulsed laser deposition. Journal of Applied Physics 1999, 86 (1), 408-411.
47. Hejazi, S.; Hosseini, H. M.; Ghamsari, M. S., The role of reactants and droplet interfaces on nucleation and growth of ZnO nanorods synthesized by vapor–liquid–solid (VLS) mechanism. Journal of Alloys and Compounds 2008, 455 (1-2), 353-357.
48. Xu, S.; Wang, Z. L., One-dimensional ZnO nanostructures: solution growth and functional properties. Nano Research 2011, 4 (11), 1013-1098.
49. Willander, M.; Nur, O.; Zhao, Q.; Yang, L.; Lorenz, M.; Cao, B.; Pérez, J. Z.; Czekalla, C.; Zimmermann, G.; Grundmann, M., Zinc oxide nanorod based photonic devices: recent progress in growth, light emitting diodes and lasers. Nanotechnology 2009, 20 (33), 332001.
50. Spanhel, L., Colloidal ZnO nanostructures and functional coatings: A survey. Journal of Sol-Gel Science and Technology 2006, 39 (1), 7-24.
51. Ji, L. W.; Peng, S. M.; Wu, J. S.; Shih, W. S.; Wu, C. Z.; Tang, I. T., Effect of seed layer on the growth of well-aligned ZnO nanowires. Journal of Physics and Chemistry of Solids 2009, 70 (10), 1359-1362.
52. Ghayour, H.; Rezaie, H.; Mirdamadi, S.; Nourbakhsh, A., The effect of seed layer thickness on alignment and morphology of ZnO nanorods. Vacuum 2011, 86 (1), 101-105.
53. Tamirat, A. G.; Rick, J.; Dubale, A. A.; Su, W.-N.; Hwang, B.-J., Using hematite for photoelectrochemical water splitting: a review of current progress and challenges. Nanoscale Horizons 2016, 1 (4), 243-267.
54. Lide, D. R., CRC handbook of chemistry and physics. CRC press: 2004; Vol. 85.
55. Jung, S.; Jeon, S.; Yong, K., Fabrication and characterization of flower-like CuO–ZnO heterostructure nanowire arrays by photochemical deposition. Nanotechnology 2010, 22 (1), 015606.
56. Kim, J.; Kim, W.; Yong, K., CuO/ZnO heterostructured nanorods: photochemical synthesis and the mechanism of H2S gas sensing. The Journal of Physical Chemistry C 2012, 116 (29), 15682-15691.
57. Farhat, O. F.; Halim, M. M.; Abdullah, M. J.; Ali, M. K.; Allam, N. K., Morphological and structural characterization of single-crystal ZnO nanorod arrays on flexible and non-flexible substrates. Beilstein Journal of Nanotechnology 2015, 6 (1), 720-725.