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Title:	Filem nipis karbon nitrida amorfus (a-CNx) sebagai sensor kelembapan
Authors:	Noor Farhana Husna bt A. Aziz (P62607 )
Supervisor:	Rozidawati binti Awang, Dr.
Issue Date:	17-Jul-2014
Description:	Amorphous carbon nitride (a-CNx) thin film has interesting characteristics such as high hardness and good electrical properties study and its application as humidity sensors. This study involves three main phases which includes the fabrication, characterization and prospects as a-CNx thin film humidity sensors. In the first phase, two sets of a-CNx thin film were deposited using plasma enhanced chemical vapor deposition technique (PECVD) for varied nitrogen (N2) gasflow rate (5-47 sccm) and for different radio frequency (RF) power (50 - 100 W). The second phase involves the characterization of these a-CNx thin films for their chemical bonding and morphology of using FTIR spectroscopy, Raman spectroscopy and FESEM. Its applicability as a humidity sensor was carried out using I-V characterization to observe the change in resistance at varied humidity. The deposition rate of a-CNx thin film was found to decrease with increasing N2 gas flow rate due to N ion bombardment during film growth which causes etching during deposition. Increasing N2 gas flow rate in above 30 sccm causes the C≡N bond content in the a-CNx thin film to decrease. The increase in N2 gas flow rate caused the decrease in ID/IGratio and the increase in the sp2 clusters size. The decrease in the ID/IGratio shows that the structure becomes more graphitic. Morphological study of the samples shows grain-like particles with dendritic structure embedded inside the grain. These dendritic structures becomemore apparent and the surface of the film becomes more porous with the increase in N2 gas flow rate. Resistance measurement for humidity sensor for this set of sample shows the high sensitivity of 468% relative to reference sample for the sample produced at N2 gas flow rate of 47 sccm. The second set of samples deposited at varied RF power show an increase in its deposition rate as RF power is increased up to 80 W and then gradually decreased with further increase in RF power. The increase in depositionrate is due to the increase in the decomposition of precursor gasses leading to the increase in the deposition of these free radicals. The gradual decrease in deposition rate occurred due to the more dominant film surface etching at higher rf power. C≡N bond content increased with the increase in RF power up to 80 W but decreased with further increase in RF power. An increase in ID/IGratio and decrease the size of sp2 clusters occurred with the increased RF power. These show that the structure becomes more graphitic with less structural defects. Surface morphology of a-CNx thin film becomes more porous when RF power is increased. The film deposited at RF power of 80 W has the highest sensitivity of 475 % relative to reference sample. In conclusion, the a-CNx thin film produced was able to detect changes in humidity, shows good repeatability and fast response to changes in humidity. This research shows that the sensitivity of a-CNxthin film as humidity sensors is not only dependent on the presence of high C≡N bond but is also influenced by the morphology of the film.,Master/Sarjana
Pages:	89
Publisher:	UKM, Bangi
Appears in Collections:	Faculty of Science and Technology / Fakulti Sains dan Teknologi

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