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,
C≡N
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 C≡N 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
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*Pengarang untuk surat-menyurat;
email: rozida@ukm.edu.my
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