Three methods were used to fabricate ZnO-based room temperature liquid petroleum gas (LPG) sensors having interdigitated metal-semiconductor-metal (MSM) structures. Specifically, devices with Pd Schottky contacts were fabricated with: (1) un-doped ZnO active layers; (2) Pd-doped ZnO active layers; and (3) un-doped ZnO layers on top of Pd microstructure arrays. All ZnO films were grown on p-type Si(111) substrates by the sol-gel method. For devices incorporating a microstructure array, Pd islands were first grown on the substrate by thermal evaporation using a 100 μm mesh shadow mask. We have estimated the sensitivity of the sensors for applied voltage from
References
[1]
Patil, D.; Patil, L. Cr2O3-modified ZnO thick film resistors as LPG sensors. Talanta 2009, 77, 1409–1414.
[2]
Shinde, V.; Gujar, T.; Lokhande, C. LPG sensing properties of ZnO films prepared by spray pyrolysis method: Effect of molarity of precursor solution. Sens. Actuators B: Chem. 2007, 120, 551–559.
[3]
Patil, L.; Bari, A.; Shinde, M.; Deo, V. Ultrasonically prepared nanocrystalline ZnO thin films for highly sensitive LPG sensing. Sens. Actuators B: Chem. 2010, 149, 79–86.
[4]
Pitcher, S.; Thiele, J.; Ren, H.; Vetelino, J. Current/voltage characteristics of a semiconductor metal oxide gas sensor. Sens. Actuators B: Chem. 2003, 93, 454–462.
[5]
Pawar, R.; Shaikh, J.; Moholkar, A.; Pawar, S.; Kim, J.; Patil, J.; Suryavanshi, S.; Patil, P. Surfactant assisted low temperature synthesis of nanocrystalline ZnO and its gas sensing properties. Sens. Actuators B: Chem. 2010, 151, 212–218.
[6]
？zgür, ü.; Alivov, Y.I.; Liu, C.; Teke, A.; Reshchikov, M.A.; Do？an, S.; Avrutin, V.; Cho, S.J.; Morko？, H. A comprehensive review of ZnO materials and devices. J. Appl. Phys. 2005, 98, 1–103.
[7]
Shinde, V.; Gujar, T.; Lokhande, C.; Mane, R.; Han, S. Development of morphological dependent chemically deposited nanocrystalline ZnO films for liquefied petroleum gas (LPG) sensor. Mater. Sci. Eng. B. 2007, 137, 119–125.
[8]
Sadek, A.; Wlodarski, W.; Li, Y.; Yu, W.; Li, X.; Yu, X.; Kalatarzadeh, K. A ZnO nanorod based layered ZnO/64 YX LiNb03 SAW hydrogen gas sensor. Thin Solid Films 2007, 515, 8705–8708.
[9]
Moore, J.; Covington, L.; Stansell, R. Affect of film thickness on the blue photoluminescence from ZnO. Phys. Status Solidi A 2012, 209, 741–745.
[10]
Moore, J.; Thompson, C. A phenomenological model for the photocurrent transient relaxation observed in ZnO photodetector devices. Sensors 2013, 13, 9921–9940.
[11]
Ali, G.; Chakrabarti, P. Performance of ZnO based ultraviolet photodetectors under varying thermal treatment. IEEE Photonics J. 2010, 2, 783–793.
[12]
Singh, P.; Singh, V.; Jain, K.; Senguttuvan, T. Pulse-like highly selective gas sensors based on ZnO nanosturctures synthesized by a chemical route: Effect of in doping and Pd loading. Sens. Actuators B: Chem. 2012, 166-167, 678–684.
[13]
Dhawale, D.; Dubai, D.; More, A.; Gujar, T.; Lokhande, C. Room temperature liquefied petroleum gas (LPG) sensor. Sens. Actuators B: Chem. 2010, 147, 488–494.
[14]
Rai, P.; Song, H.; Kim, Y.; Song, M.; Oh, P.; Yoon, J.; Yu, Y. Microwave assisted hydrothermal synthesis of single crystalline ZnO nanorods for gas sensor application. Mater. Lett. 2012, 68, 90–93.
[15]
Singh, A. Synthesis, characterization, electrical and sensing properties of ZnO nanoparticles. Adv. Powder Technol. 2010, 21, 609–613.
[16]
Xu, J.; Pan, Q.; Shun, Y.; Tian, Z. Grain size control and gas sensing properties of ZnO gas sensor. Sens. Actuators B: Chem. 2000, 66, 277–279.
[17]
Mitra, P.; Chatterjee, A.; Maiti, H. ZnO thin film sensor. Mater. Lett. 1998, 35, 33–38.
[18]
Hassan, J.; Mahdi, M.; Chin, C.; Abu-Hassan, H.; Hassan, Z. Room-temperature hydrogen gas sensor with ZnO nanorod arrays grown on a quartz substrate. Physica E 2012, 46, 254–258.
Yu, J.; Ippolito, S.; Wlodarski, W.; Strano, M.; Kalantar-zadeh, K. Nanorod based Schottky contact gas sensors in reversed bias condition. Nanotechnology 2010, 21, 265502.
[21]
Razi, F.; Irajizad, A.; Rahimi, F. Investigation of hydrogen sensing properties and aging effects of Schottky like Pd/porous Si. Sens. Actuators B: Chem. 2010, 146, 53–60.
[22]
Sahay, P.; Nath, R. Al-doped zinc oxide thin films for liquid petroleum gas (LPG) sensors. Sens. Actuators B: Chem. 2008, 133, 222–227.
[23]
Covington, L.; Moore, J. Photoconductivity and transient response of Al:ZnO:Al planar structures fabricated via a thermal oxidation process. Thin Solid Films 2013, 504, 106–111.
[24]
Moon, W.; Jun, Y.; KIm, H.; Kim, W.; Hong, S. CO gas sensing properties in Pd-added ZnO sensors. J. Electroceramics 2009, 23, 196–199.
[25]
Wei, S.; Yu, Y.; Zhou, M. CO gas sensing of Pd-doped ZnO nanofibers synthesized by electrospinning method. Mater. Lett. 2010, 64, 2284–2286.
Mitra, P.; Maiti, H. A wet-chemical process to form palladium oxide sensitizer layer on thin film zinc oxide based LPG sensor. Sens. Actuators B: Chem. 2004, 97, 49–58.
[28]
Shinde, V.; Gujar, T.; Lokhande, C. Enhanced response of porus ZnO nanobeads towards LPG: Effect of Pd sensitization. Sens. Actuators B: Chem. 2007, 123, 701–706.
[29]
Yadav, A.; Periasamy, C.; Chakrabarti, P.; Jit, S. Hydrogen gas sensing properties of Pd/nanocrystalline ZnO thin films based schottky contacts at room temperature. Adv. Sci. Eng. Med. 2013, 5, 112–118.
[30]
Xing, L.; Ma, C.; Chen, Z.; Chen, Y.; Xue, X. High gas sensing performance of one-step-synthesized Pd-ZnO nanoflowers due to surface reactions and modifications. Nanotechnology 2011, 22, 215501.
Cho, S.; Ma, J.; Kim, Y.; Sun, Y.; Wong, G.; Ketterson, J. Photoluminescence and ultraviolet lasing of polycrystalline ZnO thin films prepared by the oxidation of the metallic Zn. Appl. Phys. Lett. 1999, 75, 2761–2763.
[33]
Li, K.; Hsu, M.; Wang, I. Palladium core-porous silica shell-nanoparticles for catalyzing the hydrogenation of 4-carboxybenzaldehyde. Catal. Commun. 2008, 9, 2257–2260.
[34]
Beck, F.; de Arquer, F.G.; Bernechea, M.; Konstantatos, G. Electrical effects of metal nanoparticles embedded in ultra-thin colloidal quantum dot films. Appl. Phys. Lett. 2012, 101, 041103.
[35]
Sze, M. Physics of Semiconductor Devices, 2nd ed. ed.; Wiley/John Wiley & Sons Inc.: Hoboken, NJ, USA, 1981.
[36]
Grundmann, M. The Physics of Semiconductors: An Introduction Including Nanophysics and Applications, lst ed. ed.; Springer: Berlin, Germany, 2006.
[37]
Allen, M.; Alkaisi, M.; Durbin, S. Metal Schottky diodes on Zn-polar and O-polar bulk ZnO. Appl. Phys. Lett. 2006, 89, 103520.
[38]
Chuah, L.; Hassan, Z.; Abu-Hassan, H. Dark current characteristics of Ni contacts on porous AlGaN-based UV photodetector. J. Optoelectron. Adv. Mater. 2007, 9, 2886–2890.
[39]
Averine, S.; Chan, Y.; Lam, Y. Evaluation of Schottky contact parameters in metal-semiconductor-metal photodiode structures. Appl. Phys. Lett. 2000, 77, 274.
[40]
Tao, J.; Batzill, M. Metal Oxide Nanomaterials for Chemical Sensors, Integrated Analytical Systems; Springer: New York, NY, USA, 2013; pp. 35–66.
[41]
Wright, S.; Lim, W.; Norton, D.; Pearton, S.; Ren, F.; Johnson, J.; Ural, A. Nitride and oxide semiconductor nanostructured hydrogen gas sensors. Semicond. Sci. Technol. 2010, 25, 024002.
[42]
Yang, D. Advances in Nanocomposites-Synthesis, Characterization and Industrial Appliactions; InTech: Rijeka, Croatia, 2011; pp. 857–882.
[43]
Fleischer, M.; Lehmann, M. Solid State Gas Sensors, 1st ed. ed.; Springer: Berlin, Germany, 2012.
[44]
Soci, C.; Zhang, A.; Xiang, B.; Dayeh, S.; Aplin, D.; Park, J.; Bao, X.; Lo, Y.; Wang, D. ZnO nanowire UV photodetectors with high internal gain. Nano Lett. 2007, 7, 1003–1009.
[45]
Heiland, G. Homogeneous semiconducting gas sensors. Sens. Actuators 1981, 2, 343–361.
[46]
Coppa, B.; Fulton, C.; Kiesel, S.; Davis, R.; Pandarinath, C.; Burnette, J.; Nemanich, R.; Smith, D. Structural, microstructural, and electrical properties of gold films and Schottky contacts on remote plasma-cleaned, n-typeZnO(000l) surfaces. J. Appl. Phys. 2005, 97, 103517.
[47]
Zhang, N.; Yu, K.; Li, L.; Zhu, Z. Investigation of electrical and ammonia sensing characteristics of Schottky barrier diode based on a single ultra-long ZnO nanorod. Appl. Surface Sci. 2008, 254, 5736–5740.
[48]
Ghosh, A.; Sharma, R.; Ghule, A.; Taur, V.; Joshi, R.; Desale, D.; Guage, Y.; Jadhav, K.; Han, S. Low temperature LPG sensing properties of wet chemically grown zinc oxide nanoparticle thin film. Sens. Actuators B: Chem. 2010, 146, 69–74.
