Sains Malaysiana 46(3)(2017): 509–514

http://dx.doi.org/10.17576/jsm-2017-4603-20

 

Characterization of a-CNxThin Films Prepared by RF-PECVD Technique for

Humidity Sensor

(Pencirian ke atas Filem Nipis a-CNx daripada Teknik RF-PECVD sebagai Pengesan Kelembapan)

 

R. AWANG*, N.F.H AZIZ, N. PURHANUDIN & Z. ZALITA

 

Pusat Pengajian Fizik Gunaan, Fakulti Sains dan Teknologi, Universiti Kebangsaan Malaysia,

43600 UKM Bangi, Selangor Darul Ehsan, Malaysia

 

Diserahkan: 1 Jun 2013/Diterima: 1 Jun 2016

 

ABSTRACT

In this work, amorphous carbon nitride (a-CNx) thin films were deposited by radio frequency (RF) plasma enhanced chemical vapor deposition (RF-PECVD) technique. The RF power and gas mixture of methane (CH4) and nitrogen (N2) flow was kept constant, while the electrode distance was varied from 1 to 6 cm. The effect of electrode distance on the chemical bonding, morphology and humidity sensing responses of the films were investigated. Fourier transform infra-red spectroscopy (FTIR) studies showed a systematic change in the spectra and showed three main peaks namely the G and D-peak, CN triple bonds and C-H/O-H groups. Uniform and porous morphology was observed for films deposited at smallest distance followed by non-porous cubicle-like grain as electrode distance increased. Subsequently formation of vertically aligned nanostructures apparent both from its surface and cross section images by increasing of electrode distance to the fullest. The humidity sensing property has been studied by recording their resistance response to relative humidity (RH) at room temperature. It was found that the resistance value decreases from 15.4 to 3.6 kΩ with the increase in RH from 9 to 85%, with the highest sensitivity of 77% for film deposited at smallest distance of 1 cm.

 

Keywords: Electrode distance; nitrile bands; resistance

 

ABSTRAK

Dalam penyelidikan ini, filem nipis karbon nitrida amorfus (a-CNx) disediakan menggunakan teknik pemendapan wap kimia secara peningkatan plasma (RF-PECVD) berfrekuensi radio (RF). Kuasa RF dan kadar aliran campuran gas yang terdiri daripada metana (CH4) dan nitrogen (N2) dikekalkan malar, manakala jarak elektrod diubah pada 1 hingga 6 cm. Kesan perubahan jarak elektrod semasa proses pemendapan filem ke atas ikatan kimia, morfologi dan tindak balas pengesanan kelembapan filem dikaji. Pencirian menggunakan spektroskopi transformasi Fourier inframerah (FTIR) menunjukkan perubahan sistematik pada spektrum dan menunjukkan tiga puncak utama yang dikenali sebagai puncak G dan D, ikatan ganda tiga CN dan kumpulan C-H/O-H. Filem a-CNx menunjukkan morfologi berongga apabila filem dimendapkan pada jarak elektrod paling hampir diikuti dengan morfologi filem tidak berliang dan butiran berbentuk kubus apabila jarak elektrod ditingkatkan. Pembentukan struktur-nano yang menegak dan sejajar amat jelas kelihatan pada kedua-dua imej daripada permukaan dan keratan rentas filem yang dimendapkan pada jarak elektrod paling jauh. Sifat pengesanan kelembapan dikaji dengan merekodkan nilai rintangan filem dalam kelembapan relatif (RH) yang berbeza pada suhu bilik. Nilai rintangan didapati berkurang daripada 15.4 kepada 3.6 kΩ dengan peningkatan kelembapan relatif (RH), 9 hingga 85%. Kepekaan terhadap kelembapan tertinggi dicapai sebanyak 77% oleh filem yang dimendap pada jarak elektrod yang terhampir iaitu 1 cm.

 

Kata kunci: Ikatan nitril; jarak elektrod; rintangan

 

RUJUKAN

 

Aono, M. & Nitta, S. 2002. High resistivity and low dielectric constant amorphous carbon nitride films: application to low-k materials for ULSI. Diamond and Related Materials 11(3): 1219-1222.

Aziz, N.H., Ritikos, R., Kamal, S.A.A., Hussain, N.M. & Awang, R. 2013a. Effect of RF power and annealing on chemical bonding and morphology of a-CNx thin films as humidity sensor. Proceedings of the Universiti Kebangsaan Malaysia, Faculty of Science and Technology 2013 Postgraduate Colloquium 1571(1): 125-131. AIP Publishing.

Aziz, N.F.H., Ritikos, R., Kamal, S.A.A. & Awang, R. 2013b. Optimizing rf power for preferential C≡N bond formation in a-CNx thin films prepared by rf-PECVD technique. Journal of Physics: Conference Series 431(1): 012009.

Bronlund, J. & Paterson, T. 2004. Moisture sorption isotherms for crystalline, amorphous and predominantly crystalline lactose powders. International Dairy Journal 14(3): 247-254.

Cappelli, E., Trucchi, D.M., Kaciulis, S., Orlando, S., Zanza, A. & Mezzi, A. 2011. Effect of deposition temperature on chemical composition and electronic properties of amorphous carbon nitride (a-CNx) thin films grown by plasma assisted pulsed laser deposition. Thin Solid Films 519(12): 4059-4063.

Chu, J., Peng, X., Feng, P., Sheng, Y. & Zhang, J. 2013. Study of humidity sensors based on nanostructured carbon films produced by physical vapor deposition. Sensors and Actuators B: Chemical 178: 508-513.

Crunteanu, A., Charbonnier, M., Romand, M., Vasiliu, F., Pantelica, D., Negoita, F. & Alexandrescu, R. 2000. Synthesis and characterization of carbon nitride thin films obtained by laser induced chemical vapour deposition. Surface and Coatings Technology 125(1): 301-307.

Fang, F., Futter, J., Markwitz, A. & Kennedy, J. 2009. UV and humidity sensing properties of ZnO nanorods prepared by the arc discharge method. Nanotechnology 20: 245502-1- 245502-7.

Kim, Y.Y., Alwi, H.A., Awang, R. & Krishnaswamy, S. 2011. Influence of radio frequency power on thermal diffusivity of plasma enhanced chemical vapor deposition-grown hydrogenated amorphous carbon thin-films. Journal of Applied Physics 109(11): 113503.

Lee, J.G. & Lee, S.P. 2005a. Humidity sensing properties of CN x film by RF magnetron sputtering system. Sensors and Actuators B: Chemical 108(1): 450-454.

Lee, J.G. & Lee, S.P. 2005b. Surface analysis and humidity-sensing properties of carbon nitride films for microsensors. Journal of the Korean Physical Society 47: S429-S433.

Lee, J.G. & Lee, S.P. 2004. Nano-structured carbon nitride film for humidity sensor applications. Journal Korean Physical Society 45: 619-622.

Motta, E.F. & Pereyra, I. 2004. Amorphous hydrogenated carbon-nitride films prepared by RF-PECVD in methane-nitrogen atmospheres. Journal of Non-Crystalline Solids 338: 525- 529.

Muhl, S., Gaona-Couto, A., Méndez, J.M., Rodil, S., Gonzalez, G., Merkulov, A. & Asomoza, R. 1997. Production and characterisation of carbon nitride thin films produced by a graphite hollow cathode system. Thin Solid Films 308: 228-232.

Mutsukura, N. & Akita, K.I. 1999. Deposition of hydrogenated amorphous CNx film in CH 4/N 2 RF discharge. Diamond and Related Materials 8(8): 1720-1723.

Noor Farhana Husna Abdul Aziz. 2014. Filem nipis amorfus karbon nitrida (a-CNx) sebagai sensor kelembapan. MSc Thesis. Universiti Kebangsaan Malaysia, Malaysia (Unpublished).

Nur Maisarah binti Abdul Rashid. 2013. Hybrid plasma enhanced chemical vapour deposition/sputtering system for preparation of luminescent silicon carbon films. Master Thesis, University of Malaya, Malaysia (Unpublished).

Nystrom, M., Murtomaa, M. & Salonen, J. 2012. Effect of drying pressure on pore formation of drug particles produced by electrospraying. Joint Electrostatics Conference.

Othman, M., Ritikos, R., Khanis, N.H., Rashid, N.M.A., Rahman, S.A., Ab Gani, S.M. & Muhamad, M.R. 2011. Effects of rf power on the structural properties of carbon nitride thin films prepared by plasma enhanced chemical vapour deposition. Thin Solid Films 519(15): 4981-4986.

Richard Anak Ritikos. 2011. Fabrication and characterization of polymeric and nanostructured carbon nitride thin films: A simple difference in electrode distance. PhD. Thesis, University of Malaya, Malaysia (Unpublished).

Saha, D., Giri, R., Mistry, K.K. & Sengupta, K. 2005. Magnesium chromate-TiO2 spinel tape cast thick film as humidity sensor. Sensors and Actuators B: Chemical 107(1): 323-331.

Schwarzer, A., Saplinova, T. & Kroke, E. 2013. Tri-s-triazines (s-heptazines)-From a ‘mystery molecule’ to industrially relevant carbon nitride materials. Coordination Chemistry Reviews 257(13): 2032-2062.

Sung, C.M. & Sung, M. 1996. Carbon nitride and other speculative superhard materials. Materials Chemistry and Physics 43(1): 1-18.

Tamura, N., Aono, M., Harata, T., Kishimura, H., Kitazawa, N. & Watanabe, Y. 2014. DC electrical conductivity study of amorphous carbon nitride films prepared by reactive RF magnetron sputtering. Japanese Journal of Applied Physics 53(2S): 02BC03.

Zhou, Y., Tang, L., Zeng, G., Chen, J., Cai, Y., Zhang, Y. & Tang, W. 2014. Mesoporous carbon nitride based biosensor for highly sensitive and selective analysis of phenol and catechol in compost bioremediation. Biosensors and Bioelectronics 61: 519-525.

 

 

*Pengarang untuk surat-menyurat; email: rozida@ukm.edu.my

 

 

 

 

 

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