Papers by Muhammad Yahaya
The effect of dopants on the sensing selectivity of SnO/sub 2/ thin films-based gas sensors
ICONIP '02. Proceedings of the 9th International Conference on Neural Information Processing. Computational Intelligence for the E-Age (IEEE Cat. No.02EX575), 2002
The development of metal oxide gas sensor devices with optimized selectivity and sensitivity has ... more The development of metal oxide gas sensor devices with optimized selectivity and sensitivity has been gaining prominence in recent years. This paper reports the influence of doping to optimize the selectivity of the SnO2 thin films doped with Pt, Pd, CuO, ZnO and TiO2 toward the variety of vapor gases such as cyclohexane, chloroform, benzene and acetone. The films were prepared by using electron beam evaporation. The sensing selectivity was based on the electrical change of the films when being exposed to vapor gases. Each film shows a different response toward different vapor gases. The selectivity of these films was observed to be depended markedly on the doping materials.
Optical sensing of tea aroma using n-tetraphenyl porphine manganese (III) chloride thin films
ICSE 2000. 2000 IEEE International Conference on Semiconductor Electronics. Proceedings (Cat. No.00EX425), 2000
The aroma emerging from food samples gives specific information on quality, freshness and flavour... more The aroma emerging from food samples gives specific information on quality, freshness and flavours. This paper reports the use of a porphyrin derivative, n-tetraphenyl porphine manganese (III) chloride thin films for detection of tea aroma. The thin films were deposited on a glass substrate by the Langmuir-Blodgett technique. The experiments were performed using optical fiber reflectance with three different color LEDs, i.e. red (λ=650 nm), yellow (λ=585 nm) and green (λ=563 nm), as light sources. The sensing sensitivity was measured based on the change in the optical absorption spectra of the reflected light from the film. The reflected light from the thin films was sensitive to the tea aroma. The intensity of the reflected light decreased in the presence of the aroma
Growth And Synthesis Of ZnO Nanorod Arrays By A Chemical Solution Method
AIP Conference Proceedings, 2010
ZnO is an n-type, wide band gap II-VI compound semiconductor with a band gap energy of 3.37 eV at... more ZnO is an n-type, wide band gap II-VI compound semiconductor with a band gap energy of 3.37 eV at room temperature. ZnO possesses a large exciton binding energy hence its nanowires and nanorods have been regarded as one of the most promising materials for nanoscale electronic and optoelectronic devices such as laser diodes, optical detectors and switches. Several techniques have been utilized to fabricate ZnO nanoscale materials, such as molecular beam epitaxy, sputtering, chemical vapor deposition, spray pyrolysis, pulsed laser deposition (PLD), anodic alumina oxide (AAO) template, electrochemical deposition, and aqueous solution deposition methods. In an attempt to prepare the best quality nanowires, we chose a chemical solution method. This paper reports the preparation and characterization of nanorod arrays of ZnO on ITO glass substrates which were pre-coated with ZnO. The structural and optical properties of ZnO nanorod arrays were investigated using scanning electron microscopy, X-ray diffraction and photoluminescence (PL) techniques. It was shown that ZnO seed layer annealed at 300° C with a particle size of 10-20 nm appears on the ITO substrate. The introduction of annealed ZnO nanoparticles seed layer is required for the formation of well-aligned ZnO nanorods. The ZnO nanorod arrays with a diameter of 40-70 nm and a length of 200-300 nm were obtained. Besides, a strong UV emission in the PL spectrum revealed the good crystal quality of ZnO nanorods.
Electrochromism of copper phthalocyanine thin films
Solid State lonics 8688 (1996) 983985 SOLID STATE IONICS Electrochromism of copper phthalocyanine... more Solid State lonics 8688 (1996) 983985 SOLID STATE IONICS Electrochromism of copper phthalocyanine thin films Muftah Bakkush, Muhamad Mat Salleh, Muhammad Yahaya, Ibrahim Abu Talib* Department of Physics, Universiti Kebangsaan Malaysia, 43600 UKM, Bangi, Selangor, Malaysia ...
International Journal of Photoenergy, 2013
e in�uence of polymer solution concentration on the performance of chlorobenzene-(CB-) and chlor... more e in�uence of polymer solution concentration on the performance of chlorobenzene-(CB-) and chloroform-(CF-) based inverted-type organic solar cells has been investigated. e organic photoactive layers consisted of poly(2-methoxy-5-(2-ethyl hexyloxy)-1,4-phenylenevinylene) (MEH-PPV) and (6,6)-phenyl C 61 butyric acid methyl ester (PCBM) were spin coated from CF with concentrations of 4, 6, and 8 mg/mL and from CB with concentrations of 6, 8, and 10 mg/mL onto Eosin-Y-coated ZnO nanorod arrays (NRAs). Fluorine doped tin oxide (FTO) and silver (Ag) were used as electron collecting electrode and hole collecting electrode, respectively. Experimental results showed that the short circuit current density and power conversion efficiency increased with decrease of solution concentration for both CB and CF devices, which could be attributed to reducing charge recombination in thinner photoactive layer and larger contact area between the rougher photoactive layer and Ag contact. However, the open circuit voltage decreased with decreasing solution concentration due to increase of leakage current from ZnO NRAs to Ag as the ZnO NRAs were not fully covered by the polymer blend. e highest power conversion efficiencies of 0.54 ± 0.10% and 0.87 ± 0.15% were achieved at the respective lowest solution concentrations of CB and CF.
ZnO nanorod arrays pre-coated with DCJTB dye for inverted type hybrid solar cells incorporating P3HT donor
Journal of Materials Science: Materials in Electronics, 2014
ABSTRACT This paper reports the utilization of a fluorescent dye, 4-(dicyanomethylene)-2-tert-but... more ABSTRACT This paper reports the utilization of a fluorescent dye, 4-(dicyanomethylene)-2-tert-butyl-6-(1,1,7,7-tetra-methyljulolidyl-9-enyl)-4H-pyran (DCJTB) as the surface modifier of ZnO nanorods for inverted type hybrid solar cell application. The DCJTB solution with concentrations of 10 and 15 mM was spin-coated onto the ZnO nanorod arrays grown on the fluorine-doped tin oxide glass substrate pre-coated with ZnO seed layer. The poly(3-hexylthiophene-2,5-diyl) (P3HT) as electron donor was then spin-coated onto ZnO nanorod arrays, followed by the deposition of silver as anode using magnetron sputtering technique. A large portion of pre-coated DCJTB has been redissolved and washed out in the subsequent P3HT spin coating process. Nevertheless, the increase in hydrophobicity of ZnO nanorod arrays pre-coated with DCJTB leads to improved interfacial compatibility between ZnO nanorods and P3HT. As a result, the enhanced exciton dissociation efficiency at the ZnO nanorods/P3HT interfaces results in the increment of short circuit current density and open circuit voltage. In addition, DCJTB residue covering the FTO exposed area could reduce the hole leakage current from P3HT to FTO, hence resulting in higher open circuit voltage. The device with the optimum DCJTB pre-coating concentration of 10 mM exhibited almost two times increase in power conversion efficiency as compared to that of pristine device.
ICSE '96. 1996 IEEE International Conference on Semiconductor Electronics. Proceedings
The Sb-doped SnO, thin films have been developed for gas sensors applications. The mechanism of s... more The Sb-doped SnO, thin films have been developed for gas sensors applications. The mechanism of sensing is based on the absorption and desorption of gases on the films surface that change the electrical resistivity of the Jilms. ThinJilms of SnO2 were prepared on the glass slide substrates by spray pyrolysis method. The films in the range of 2000-5000 A are very sensitive to 0, and CO, and less sensitive to NI gas. The basic principles of the mechanism of action will be described in details.
Effect of Electric Field Treatment on the Performance of Organic Salt Doped Solar Cell
Advanced Materials Research, 2012
High efficiency is one of the characteristics of a good solar cell. The objective of the experime... more High efficiency is one of the characteristics of a good solar cell. The objective of the experiment is to investigate the effect of electric field treatment on the performance of organic salt tetrabutylammonium hexafluorophosphate (TBAPF6) doped solar cell with ITO/MEHPPV:PCBM/Al structure where indium tin oxide (ITO) was used as anode, poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEHPPV) as donor, (6,6)-phenyl-C61 butyric acid methyl ester (PCBM) as acceptor and aluminium (Al) as cathode. The devices were build by depositing 20 % of TBAPF6 (weight percentage with respect to MEHPPV) doped MEHPPV:PCBM thin film onto the ITO by spin coating technique, and followed by deposition of Al by using electron gun evaporation technique. The performance of the devices was analyzed through the current-voltage (I-V) curve under illumination with a solar simulator at 100 mW/cm2. Electric field treatment was given by applying different constant voltages of 6 V, 8 V and 10 V for 60 s t...
Effect of Annealing on the Sol-Gel Derived SrBi4Ti4O15 Thin Films for Piezoelectric Pressure Sensors
2006 IEEE International Conference on Semiconductor Electronics, 2006
This paper reports the effect of annealing on fabrication of Strontium Bismuth Titanate SrBi4Ti4O... more This paper reports the effect of annealing on fabrication of Strontium Bismuth Titanate SrBi4Ti4O15 (SBT) thin films for piezoelectric pressure sensors. The SBT films and capacitance devices with structure of Al/TiO2/SBT/TiO2/SiO2/Si were fabricated using sol-gel technique. The microstructure of SBT thin films have been systematically studied in as-prepared (un- annealed) condition as well as after annealing at 400, 500, 600 and 700 degC. The general trend seems to indicate that annealed temperature show better piezoelectric properties. X-ray diffraction patterns reveal changes of crystalline structure after annealing at 600 degC temperature. Another important parameter is dielectric constant, which is found toward higher value within annealing temperature. For the sensor device measurement, the SBT thin film pressure sensors were tested by pneumatic loading method at pressure range between 0 to 450 kPa. It found that the sensors sensitive to the applied pressure and the response recovered back when the pressure were removed. The 600 degC annealed pressure sensor demonstrates better repeatability compared to the others. The results indicated that the sensor performance was affected by the structure of the film. A crystalline structure gives an optimum response towards pneumatic pressure. However, the too high of annealing temperature may cause a catastrophic failure of the pressure sensor response, hence the existing of crack and inter diffusion between top and bottom electrode. The correlation between annealing process with structure of SBT pressure sensors and the piezoelectric properties will be discussed.
Synthesis of silicon nanowires
2004 IEEE International Conference on Semiconductor Electronics, 2004
... Wong Yuen Yee, Muhammad Yahaya, MIEEE, Muhamad Mat Salleh, MIEEE and Burhanuddin Yeop Majlis,... more ... Wong Yuen Yee, Muhammad Yahaya, MIEEE, Muhamad Mat Salleh, MIEEE and Burhanuddin Yeop Majlis, SMIEEE Institute of Microengineering and Nanoelectronics (IMEN ... [14] "X-ray studies of AuSi Eutectic Alloy" from the website of 0. Shpyrko: http://liquids.deas.harvard.edu ...
Detection of fungicide in water by ZnCdSe quantum dots thin film
2010 IEEE International Conference on Semiconductor Electronics (ICSE2010), 2010
Abstract Quantum dots (QDs) thin film sensor was developed to detect fungicide in water by optica... more Abstract Quantum dots (QDs) thin film sensor was developed to detect fungicide in water by optical sensing system. The ZnCdSe QDs was synthesized using a wet-chemical process to apply in this fluorescent sensor. A sensor system was setup, comprises an excitation light source ...
Detection of Formaldehyde Using Plasmonic Properties of Gold Nanoparticles <sup></sup>
Key Engineering Materials, 2011
This paper reports a study on plasmonic properties of gold nanoparticles to detect the presence o... more This paper reports a study on plasmonic properties of gold nanoparticles to detect the presence of formaldehyde solution in water. Gold nanoparticles were grown on substrates by the seed mediated growth method. A sensor system was setup, comprises a light source, a dual arm fibre optic probe, a spectrometer and sensor chamber. The detection of formaldehyde was done by comparing the Localized Surface Plasmon Resonance (LSPR) spectra of gold nanoparticles samples immersed in the deionised water and formaldehyde solution. It was observed that the peak position LSPR spectra of nanogold samples and their intensity were change by the presence formaldehyde. The difference between resonance peak intensity of LSPR spectra gold nanoparticles sample in formaldehyde solution and water can be used as sensing sensitivity parameter of the sensor. It was found that the sensing sensitivity is increase with the size of nanoparticles until it reach the optimum particles size.
Optical Electronic Nose Based on Fe (III) Complex of Porphyrins Films for Detection of Volatile Compounds
Key Engineering Materials, 2011
Electronic nose is a device that attempts to mimic the living being smell system for detection of... more Electronic nose is a device that attempts to mimic the living being smell system for detection of particular gases or volatile compounds. This paper reports the development of an optical electronic nose using Fe (III) based metalloporphyrins Langmuir-Blodgett thin films as sensing elements for discriminating four volatiles, 2-propanol, acetone, cyclohexane and ethanol. A multilayer feed forward neural network was developed to classify the input vectors from these two sensors. After the network being trained 100 times and introduced to blind samples, it was found that there are three fault decision for propanol, two for acetone, five for cyclohexane and one four ethanol, during 50 times being recognized to the samples.
Thin Solid Films, 2009
White organic light emitting diode (OLED) devices with the structure ITO/PHF:rubrene/Al, in which... more White organic light emitting diode (OLED) devices with the structure ITO/PHF:rubrene/Al, in which PHF (poly(9,9-din -hexylfluorenyl-2,7-diyl)) is used as blue light emitting host and rubrene (5,6,11,12tetraphenylnapthacene) as an orange dye dopant, have been fabricated. Indium tin oxide (ITO) coatedglass and aluminium were used as anode and cathode, respectively. The devices were fabricated with various rubrene-dopant to obtain a white light emission. The OLED device that composed of several concentrations of rubrene-doped PHF film was prepared in this study. It was found that the concentration of rubrene in the PHF-rubrene thin film matrix plays a key role in producing the white color emission. In a typical result, the device composed of 0.06 wt.% rubrene-dopant produced the white light emission with the Commission Internationale de L'Eclairage (CIE) coordinate of (0.30,0.33). The turn-on voltage and the brightness were found to be as low as 14.0 V and as high as 6540 cd/m 2 , respectively. The annealing technique at relatively low temperature (50°C, 100°C, and 150°C) was then used to optimize the performance of the device. In a typical result, the turn-on voltage of the device could be successfully reduced and the brightness could be increased using the annealing technique. At an optimum condition, for example, annealed at 150°C, the turnon voltage as low as 8.0 V and the brightness as high as 9040 cd/m 2 were obtained. The mechanism for the improvement of the device performance upon annealing will be discussed.
Fluorescence Properties of Hybrid CdTe Quantum Dots-Porphyrins Thin Films in Organic Vapors
This paper reports a study on the fluorescence properties of thin films utilizing quantum dots (Q... more This paper reports a study on the fluorescence properties of thin films utilizing quantum dots (QDs) of cadmium telluride (CdTe) hybridized with porphyrins (tetraphenyl porphine cobalt (II)) (CoTTP) thin films under exposure of various gases. The high yellow luminescence ...
Effect of annealing process on the phase formation in poly(vinylidene fluoride) thin films
AIP Conference Proceedings, 2014
ABSTRACT Articles you may be interested in The creep process of the domain switching in poly(viny... more ABSTRACT Articles you may be interested in The creep process of the domain switching in poly(vinylidene fluoride-trifluoroethylene) ferroelectric thin films Appl. Phys. Lett. 103, 042909 (2013); 10.1063/1.4816749 Organic hydrogen gas sensor with palladium-coated-phase poly(vinylidene fluoride) thin films Appl. Phys. Lett. 101, 181907 (2012); 10.1063/1.4764064 Polarization of poly(vinylidene fluoride) and poly(vinylidene fluoride-trifluoroethylene) thin films revealed by emission spectroscopy with computational simulation during phase transition J. Appl. Phys. 111, 104113 (2012); 10.1063/1.4721373 Spin cast ferroelectric beta poly(vinylidene fluoride) thin films via rapid thermal annealing Appl. Phys. Lett. 92, 012921 (2008); 10.1063/1.2830701 The effect of surface nucleation on the crystallization of the phase of poly(vinylidene fluoride) J. Appl. Phys. 51, 5145 (1980) Abstract. This work reports the initial study on the effect of annealing process on the crystalline phase of poly(vinylidene fluoride) (PVDF) thin film. PVDF powder was dissolved in N,N-dimethylformamide before spin-coated onto a glass substrate to form a film. The films were annealed at 30°C, 90°C and 110°C for 5 hrs. The crystalline phase of the powder PVDF as received was investigated by using XRD and FTIR techniques. Moreover, the crystalline phases of thin films after annealing were investigated by using the same techniques. XRD analysis showed that in powder form PVDF exists in α-phase. Each annealed PVDF thin films exhibited identical formation of three-phases material namely γ (as major phase) while α and β phases as the minor phases. The FTIR analysis showed that the powder form of PVDF exists in α and β phases. FTIR measurement further confirmed the XRD results implying that the annealing process has no significant effect on the phase formation in PVDF films.
Enhancement of ZnO nanorod arrays-based inverted type hybrid organic solar cell using spin-coated Eosin-Y
Semiconductor Science and Technology, 2013
ABSTRACT
Journal of Alloys and Compounds, 2014
The Mg concentration dependence of the performance of inverted type organic solar cells based on ... more The Mg concentration dependence of the performance of inverted type organic solar cells based on Mgdoped ZnO nanorod arrays and poly(3-hexylthiophene) (P3HT) has been investigated. The Mg dopants with various concentrations (0, 1, 3 and 5 at.%) were introduced during the hydrothermal growth of the ZnO nanorod arrays on fluorine-doped tin oxide (FTO) glass substrate. The P3HT was deposited onto Mg-doped ZnO nanorod arrays by spin coating technique, followed by deposition of Ag as anode using magnetron sputtering technique. The length and density of Mg-doped ZnO nanorods increased, whereas the diameter decreased with the Mg concentration. The short circuit current density (J sc) and open circuit voltage (V oc) improved with increasing of Mg concentration up to 3 at.%, which could be attributed to increased interfacial area for more efficient exciton dissociation and reduced charge recombination as a result of lower number of oxygen interstitials which act as electron traps in ZnO. However, the J sc and V oc started to decrease at Mg concentration of 5 at.%, mainly due to poor infiltration of P3HT into the high-density 5 at.% Mg-doped ZnO nanorod arrays and increase of Mg dopant-related trapping centers. The highest power conversion efficiency of 0.36 ± 0.02% was achieved at Mg doping concentration of 3 at.%, an enhancement of 225% as compared to that based on undoped ZnO nanorod arrays.
Optical gas sensing selectivity property of ruthenium (II)-metalloporphyrins Langmuir–Blodgett films
Current Applied Physics, 2008
This paper reports the study of the selectivity property of a metalloporphyrins derivative Langmu... more This paper reports the study of the selectivity property of a metalloporphyrins derivative LangmuirBlodgett thin film, n-octaethyl porphine ruthenium (II) carbonyl (RuOEPCO), to several organic gas samples, namely the saturated vapor of acetone, 2-propanol, ethanol and ...
Current Applied Physics, 2009
The effect of tetrabutylammonium hexafluorophosphate (TBAPF 6) doping on the electrical and elect... more The effect of tetrabutylammonium hexafluorophosphate (TBAPF 6) doping on the electrical and electroluminescence properties of single-layer polymer light emitting diodes (PLEDs) with ITO/PVK:PBD/Al structure were investigated where indium tin oxide (ITO) was used as anode, poly(9-vinylcarbazole) (PVK) as polymeric host, 2-(4biphenylyl)-5-phenyl-1,3,4-oxadiazole (PBD) as electron-transporting molecule and aluminium (Al) as cathode. The emitting layers were spin-coated onto the ITO-coated glass substrates. It was found that the doped devices underwent transition at the first voltage scan where the current increased drastically at certain voltage. After the transition, the threshold voltage for current injection as well as the light emission decreased significantly as compared to undoped device. The turn on voltage of the doped device was 5 V. The significant improvement was attributed to the reduction of both electron and hole injection energy barriers caused by accumulation of ionic species at the interface. In conclusion, doping of TBAPF 6 has been shown to be a valuable approach to reduce the turn-on voltage and increase the EL intensity of PLEDs.
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Papers by Muhammad Yahaya