Ayib Rosdi Bin Zainun | Universiti Malaysia Pahang (UMP) (original) (raw)

Papers by Ayib Rosdi Bin Zainun

Proceedings of the First EAI International Conference on Computer Science and Engineering, 2017

Interference reduction one of the major problem in the wireless communication systems. Minimum Va... more Interference reduction one of the major problem in the wireless communication systems. Minimum Variance Distortionless Response (MVDR) Beamformer is the process of extracting the user-of-interest (UOI) signal from interferer signals and external noise. In the present work, Gravitational Search Algorithm (GSA) is a new modern metaheuristic optimization technique used for optimizing the MVDR null-forming level by controlling the excitation weight coefficients in a linear antenna array radiation pattern synthesis. The best set of complex excitation coefficients solution in multidimensional problems evaluated based on two figure of merit, signal-to-interference-plus-noise ratio (SINR) and beampattern accuracy for two scan angles. The results reported here have been compared with the results of conventional MVDR technique. MVDRGSA successfully used to calculate the excitation weight coefficients with the desired patterns for both accurate beam shaping and introduce deep pattern nulling. It found that the SINR and output beampattern were in good agreement with MVDRGSA.

Energy efficiency (EE) of wireless telecommunications has become a new challenge for the research... more Energy efficiency (EE) of wireless telecommunications has become a new challenge for the research community, governments and industries in order to reduce CO 2 emission and operational costs. EE of base stations (BSs) in cellular networks is a growing concern for cellular operators to not only maintain profitability, but also to reduce the overall negative impact to the environment and economic issues for wireless network operators. In this paper, a framework focuses on the Area Energy Efficiency (AEE) evaluation of LTE BSs is presented. The parameters affect on the AEE and the coverage area of LTE BS in different scenarios are investigated. AEE analysis has been done using a few key performance indicators including transmit power, bandwidth, load factor with the assumption of different scenarios (urban, suburban and rural). The simulation results show that the LTE BSs have better AEE in an urban environment for cell radius less than 750 m compare with the suburban and rural environ...

Indian Journal of Science and Technology, 2016

Minimum Variance Distortionless Response (MVDR) is basically a unity gain adaptive beamformer whi... more Minimum Variance Distortionless Response (MVDR) is basically a unity gain adaptive beamformer which is suffered from performance degradation due to the presence of interference and noise. Also, MVDR is sensitive to errors such as the steering vector errors, and the nulling level. MVDR combined with a Linear Antenna Array (LAA) is used to acquire desired signals and suppress the interference and noise. This paper examines the impact of the number of interference sources and the mainlobe accuracy by using Signal to Interference plus Noise Ratio (SINR) and array beampattern as two different Figure-of-Merits to measure the performance of the MVDR beamformer with a fixed number of array elements (L). The findings of this study indicate that the MVDR successfully form a nulls to L-1 nonlook signal with average SINR of 49.31 dB. Also, the MVDR provides accurate mainlobe with a small change to the real user direction when the SNOIs are bigger than array elements. The proposed method was found to perform better than some existing techniques. Based on this analysis, the beampattern not heavily relies on the number of unwanted source. Moreover, the SINR strongly depends on the number of SNOIs and the nulling level.

2012 10th IEEE International Conference on Semiconductor Electronics (ICSE), 2012

ABSTRACT In this paper, the copper (I) iodide (CuI) thin films were prepared by mister atomizer w... more ABSTRACT In this paper, the copper (I) iodide (CuI) thin films were prepared by mister atomizer with different thickness. The effect of thickness of CuI thin films were done by varying the deposition flow rate and deposition time. The effects of thickness to its structural, electrical and optical properties were studied. The resistivity increases as the thickness of thin film increase with highest resistivity of 4.79 × 101 Ω cm. The transmittance for most of the samples was transparent of above 80% in the visible wavelength. The transmittance and absorption coefficient was measured and then the energy gap was determined which shows the direct transition of n=2. The maximum band gap observed here is 2.82 eV for the thickest thin films. The observation on effect of thickness in this study shows that the increasing of thin film thickness increased the resistivity while the absorption coefficient decrease with slight rise of band gap which due to the bulk grain properties for thick thin film.

Minimum Variance Distortionless Response (MVDR) is basically a unity gain adaptive beamformer whi... more Minimum Variance Distortionless Response (MVDR) is basically a unity gain adaptive beamformer which is suffered from performance degradation due to the presence of interference and noise. Also, MVDR is sensitive to errors such as the steering vector errors, and the nulling level. MVDR combined with a Linear Antenna Array (LAA) is used to acquire desired signals and suppress the interference and noise. This paper examines the impact of the number of interference sources and the mainlobe accuracy by using Signal to Interference plus Noise Ratio (SINR) and array beampattern as two different Figure-of-Merits to measure the performance of the MVDR beamformer with a fixed number of array elements (L). The findings of this study indicate that the MVDR successfully form a nulls to L-1 nonlook signal with average SINR of 49.31 dB. Also, the MVDR provides accurate mainlobe with a small change to the real user direction when the SNOIs are bigger than array elements. The proposed method was found to perform better than some existing techniques. Based on this analysis, the beampattern not heavily relies on the number of unwanted source. Moreover, the SINR strongly depends on the number of SNOIs and the nulling level.

Proceedings of the First EAI International Conference on Computer Science and Engineering, 2017

Journal of Nanoscience and Nanotechnology, 2012

Particle size of the solution is measured after few hours of stirring. Then, the thin film was de... more Particle size of the solution is measured after few hours of stirring. Then, the thin film was deposited by spin coating technique with appropriate parameters. The optical properties of the composite thin film have been examined to display the energy shifting, which support the improved band gap compared to that of the pure CuI film, while the electrical properties show improved conductivity of the hole conductor to be a function of the p-type semiconductor for DSSC. This result indicates that the electrical and optical properties of CuI film can be easily adjusted by the formation of composite film with proper ligand agents.

Combination of potassium iodide (KI) and copper sulfate (CuSO4) as prepared solution at room temp... more Combination of potassium iodide (KI) and copper sulfate (CuSO4) as prepared solution at room temperature to produced p-type conductivity Γ-phase copper (I) iodide thin film have been studied. The solution was first prepared by simple calculation of both concentrations and disolved in certain amount of water. Mixing both liquid produced CuI precipitate where then disolve in acetonitrile which resulting CuI solution. This solution then deposited in silicon and glass substrates by spin coating technique to make CuI thin film. In order to study further details of it crystalline behaviour, annealling temparature was conducted at 4 different stages which are as deposited, 50°, 100° and 150°. The results were examined by X-ray Diffraction (XRD) for their atoms arrangement within CuI crystalline, Scanning Electron Microscope (SEM) for surface morphology and Energy dispersive X-ray spectroscopy (EDXS) for chemical characterization. Results showed that the chemical compound tested were purely copper iodide element.

ABSTRACT The effect of crystalline size of ZnO thin film towards it electrical properties was con... more ABSTRACT The effect of crystalline size of ZnO thin film towards it electrical properties was conducted and studied. Through the process of sol gel method, ZnO solution was afforded by dissolving zinc acetate dehydrate as precursor into 2-methoxyethanol as solvent and added monoethanolmine as chelating agent. This solution was then deposited onto silicon substrates to produced thin film by spin coating technique. Following the work objective, produced thin film was sintered at different temperature to analyze it grain size against the properties of electrical. Scanning electron microscopy (SEM) was used to find any enhancement in grain size of ZnO. SEM results were supported with full width at half maximum (FWHM) values that proved the ZnO grain size improved with increasing temperature. For it electrical properties, current-voltage (I-V) measurement was conducted and it showed some progress in it results.

Influence of ligand to structural and optical properties of CuI thin film has been examined. CuI ... more Influence of ligand to structural and optical properties of CuI thin film has been examined. CuI thin film has been prepared by sol-gel process with incorporation of bidentate ligand into the CuI solution. Particles size of the solution is measured after few hours of stirred. Then, the thin film was formed by spin coating technique with appropriate parameters. It optical

The work presented here shows the effect of annealing temperature on CuI thin films. The 0.05 mol... more The work presented here shows the effect of annealing temperature on CuI thin films. The 0.05 mol of CuI solution is prepared at room temperature and then deposited in silicon and glass substrate. The CuI thin films were deposited using sol-gel spin coating method. The electrical, optical properties and surface morphology was characterized by current-voltage (I-V) measurement, ultraviolet-visible (UV-VIS) measurement

Particle size of the solution is measured after few hours of stirring. Then, the thin film was de... more Particle size of the solution is measured after few hours of stirring. Then, the thin film was deposited by spin coating technique with appropriate parameters. The optical properties of the composite thin film have been examined to display the energy shifting, which support the improved band gap compared to that of the pure CuI film, while the electrical properties show improved conductivity of the hole conductor to be a function of the p-type semiconductor for DSSC. This result indicates that the electrical and optical properties of CuI film can be easily adjusted by the formation of composite film with proper ligand agents.

ABSTRACT Solid state dye-sensitized solar cells (DSSCs) were first reported in 1991 without emplo... more ABSTRACT Solid state dye-sensitized solar cells (DSSCs) were first reported in 1991 without employing p-type as hole conductor. The p-type as hole conductor was first introduced in 1995 and CuI is preferred among others p-type semiconductors. However, in 2003 utilizing of CuI based DSSC was found unstable by the excessive iodine strongly decreased the photocurrent of the cell. Later then, the stability of CuI based DSSCs was reported can be improved by added small amount of triethylamine hydrothiocyanate (THT) in the CuI coating solution. Following to that, in this work new chemical is introduce as an option to present situation which can give equally or better effective for fabrication of solid-state DSSCs. The chemical is called tetramethylethylenediamine (TMED), is employed to CuI in sol-gel process and their characterizations have been studied. The CuI coating solution was prepared by dissolved CuI powder with acetonitrile and added in 0.5mL TMED. Using spin coating technique the sol then deposited onto glass and silicon substrate at room temperature. The film were analyzed by their particles conductivity using pH meter, surface morphology using Field Emission Scanning Electron Microscope (FE-SEM) and optical properties using ultraviolet visible spectroscopy (UV-Vis) and photoluminescence (PL) measurement. The results of this sol-gel were compared with other CuI sol-gel which prepared by dissolved CuI powder with acetonitrile only. The optical transmittance within ultra-violet range exhibited that thin film is transparent and it optical band gap have been studied. Further clarification and measurements need to be done in order to prove that the proposed chemical can be used as an option.

Nanotechnology, 2015

Working electrode (WE) fabrication offers significant challenges in terms of achieving higheffici... more Working electrode (WE) fabrication offers significant challenges in terms of achieving highefficiency dye-sensitized solar cells (DSCs). We have combined the beneficial effects of vertical nanorods grown on conducting glass substrate for charge transport and mesoporous particles for dye loading and have achieved a high photoconversion efficiency of (η) > 11% with an internal quantum efficiency of ∼93% in electrode films of thickness ∼7 ± 0.5 μm. Controlling the interface between the vertical nanorods and the mesoporous film is a crucial step in attaining high η. We identify three parameters, viz., large surface area of nanoparticles, increased light scattering of the nanorod-nanoparticle layer, and superior charge transport of nanorods, that simultaneously contribute to the improved photovoltaic performance of the WE developed.

Journal of Alloys and Compounds, 2014

ABSTRACT Zinc oxide (ZnO) thin films have been deposited onto glass substrates at various deposit... more ABSTRACT Zinc oxide (ZnO) thin films have been deposited onto glass substrates at various deposition speeds by a sonicated sol-gel dip-coating technique. This work studies the effects of deposition speed on the crystallisation behaviour and optical and electrical properties of the resulting films. X-ray diffraction (XRD) analysis showed that thin films were preferentially oriented along the (0 0 2) c-axis direction of the crystal. The transformation sequence of strain and stress effects in ZnO thin films has also been studied. The films deposited at a low deposition speed exhibited a large compressive stress of 0.78 GPa, which decreased to 0.43 GPa as the deposition speed increased to 40 mm/min. Interestingly, the enhancement in the crystallinity of these films led to a significant reduction in compressive stress. All films exhibited an average transmittance of greater than 90% in the visible region, with absorption edges at ∼380 nm. The photoluminescence (PL) measurements indicated that the intensity of the emission peaks varied significantly with deposition speed. The optical band gap energy (Eg) was evaluated as 3.276–3.289 eV, which increased with decreasing compressive stress along the c-axis. The energy band gap of the resulting ZnO films was found to be strongly influenced by the preferred c-axis (0 0 2) orientation.

IOP Conference Series: Materials Science and Engineering, 2011

... the figure, the absorption value of CuI thin film prepared with TMED started to seen at 350 n... more ... the figure, the absorption value of CuI thin film prepared with TMED started to seen at 350 nm which is almost close to the TUPAC plot (not ... valence band and sub energy levels in the conduction band [2][3]. This blue shift transition could be due to the existing of nano-particles in ...

Energy efficiency (EE) of wireless telecommunications has become a new challenge for the research... more Energy efficiency (EE) of wireless telecommunications has become a new challenge for the research community, governments and industries in order to reduce CO2 emission and operational costs. EE of base stations (BSs) in cellular networks is a growing concern for cellular operators to not only
maintain profitability, but also to reduce the overall negative impact to the environment and economic issues for wireless network operators. In this paper, a framework focuses on the Area Energy Efficiency (AEE) evaluation of LTE BSs is presented. The parameters affect on the AEE and the coverage area of LTE BS in different scenarios are investigated. AEE analysis has been done using a few key performance indicators including transmit power, bandwidth, load factor with the assumption of different scenarios (urban, suburban and rural). The simulation results show that the LTE BSs have better AEE in an urban environment for cell radius less than 750 m compare with the suburban and rural environments. Furthermore, it is obvious that there is a strong influence of traffic load, BW and transmission power on AEE of LTE network. On the other hand, AEE increases significantly as the BW size increases. Finally, it has been shown that the AEE of LTE macro BS decreases with increasing the percentage of traffic load for all scenarios.

Proceedings of the First EAI International Conference on Computer Science and Engineering, 2017

Interference reduction one of the major problem in the wireless communication systems. Minimum Va... more Interference reduction one of the major problem in the wireless communication systems. Minimum Variance Distortionless Response (MVDR) Beamformer is the process of extracting the user-of-interest (UOI) signal from interferer signals and external noise. In the present work, Gravitational Search Algorithm (GSA) is a new modern metaheuristic optimization technique used for optimizing the MVDR null-forming level by controlling the excitation weight coefficients in a linear antenna array radiation pattern synthesis. The best set of complex excitation coefficients solution in multidimensional problems evaluated based on two figure of merit, signal-to-interference-plus-noise ratio (SINR) and beampattern accuracy for two scan angles. The results reported here have been compared with the results of conventional MVDR technique. MVDRGSA successfully used to calculate the excitation weight coefficients with the desired patterns for both accurate beam shaping and introduce deep pattern nulling. It found that the SINR and output beampattern were in good agreement with MVDRGSA.

Energy efficiency (EE) of wireless telecommunications has become a new challenge for the research... more Energy efficiency (EE) of wireless telecommunications has become a new challenge for the research community, governments and industries in order to reduce CO 2 emission and operational costs. EE of base stations (BSs) in cellular networks is a growing concern for cellular operators to not only maintain profitability, but also to reduce the overall negative impact to the environment and economic issues for wireless network operators. In this paper, a framework focuses on the Area Energy Efficiency (AEE) evaluation of LTE BSs is presented. The parameters affect on the AEE and the coverage area of LTE BS in different scenarios are investigated. AEE analysis has been done using a few key performance indicators including transmit power, bandwidth, load factor with the assumption of different scenarios (urban, suburban and rural). The simulation results show that the LTE BSs have better AEE in an urban environment for cell radius less than 750 m compare with the suburban and rural environ...

Indian Journal of Science and Technology, 2016

Minimum Variance Distortionless Response (MVDR) is basically a unity gain adaptive beamformer whi... more Minimum Variance Distortionless Response (MVDR) is basically a unity gain adaptive beamformer which is suffered from performance degradation due to the presence of interference and noise. Also, MVDR is sensitive to errors such as the steering vector errors, and the nulling level. MVDR combined with a Linear Antenna Array (LAA) is used to acquire desired signals and suppress the interference and noise. This paper examines the impact of the number of interference sources and the mainlobe accuracy by using Signal to Interference plus Noise Ratio (SINR) and array beampattern as two different Figure-of-Merits to measure the performance of the MVDR beamformer with a fixed number of array elements (L). The findings of this study indicate that the MVDR successfully form a nulls to L-1 nonlook signal with average SINR of 49.31 dB. Also, the MVDR provides accurate mainlobe with a small change to the real user direction when the SNOIs are bigger than array elements. The proposed method was found to perform better than some existing techniques. Based on this analysis, the beampattern not heavily relies on the number of unwanted source. Moreover, the SINR strongly depends on the number of SNOIs and the nulling level.

2012 10th IEEE International Conference on Semiconductor Electronics (ICSE), 2012

ABSTRACT In this paper, the copper (I) iodide (CuI) thin films were prepared by mister atomizer w... more ABSTRACT In this paper, the copper (I) iodide (CuI) thin films were prepared by mister atomizer with different thickness. The effect of thickness of CuI thin films were done by varying the deposition flow rate and deposition time. The effects of thickness to its structural, electrical and optical properties were studied. The resistivity increases as the thickness of thin film increase with highest resistivity of 4.79 × 101 Ω cm. The transmittance for most of the samples was transparent of above 80% in the visible wavelength. The transmittance and absorption coefficient was measured and then the energy gap was determined which shows the direct transition of n=2. The maximum band gap observed here is 2.82 eV for the thickest thin films. The observation on effect of thickness in this study shows that the increasing of thin film thickness increased the resistivity while the absorption coefficient decrease with slight rise of band gap which due to the bulk grain properties for thick thin film.

Minimum Variance Distortionless Response (MVDR) is basically a unity gain adaptive beamformer whi... more Minimum Variance Distortionless Response (MVDR) is basically a unity gain adaptive beamformer which is suffered from performance degradation due to the presence of interference and noise. Also, MVDR is sensitive to errors such as the steering vector errors, and the nulling level. MVDR combined with a Linear Antenna Array (LAA) is used to acquire desired signals and suppress the interference and noise. This paper examines the impact of the number of interference sources and the mainlobe accuracy by using Signal to Interference plus Noise Ratio (SINR) and array beampattern as two different Figure-of-Merits to measure the performance of the MVDR beamformer with a fixed number of array elements (L). The findings of this study indicate that the MVDR successfully form a nulls to L-1 nonlook signal with average SINR of 49.31 dB. Also, the MVDR provides accurate mainlobe with a small change to the real user direction when the SNOIs are bigger than array elements. The proposed method was found to perform better than some existing techniques. Based on this analysis, the beampattern not heavily relies on the number of unwanted source. Moreover, the SINR strongly depends on the number of SNOIs and the nulling level.

Proceedings of the First EAI International Conference on Computer Science and Engineering, 2017

Journal of Nanoscience and Nanotechnology, 2012

Particle size of the solution is measured after few hours of stirring. Then, the thin film was de... more Particle size of the solution is measured after few hours of stirring. Then, the thin film was deposited by spin coating technique with appropriate parameters. The optical properties of the composite thin film have been examined to display the energy shifting, which support the improved band gap compared to that of the pure CuI film, while the electrical properties show improved conductivity of the hole conductor to be a function of the p-type semiconductor for DSSC. This result indicates that the electrical and optical properties of CuI film can be easily adjusted by the formation of composite film with proper ligand agents.

Combination of potassium iodide (KI) and copper sulfate (CuSO4) as prepared solution at room temp... more Combination of potassium iodide (KI) and copper sulfate (CuSO4) as prepared solution at room temperature to produced p-type conductivity Γ-phase copper (I) iodide thin film have been studied. The solution was first prepared by simple calculation of both concentrations and disolved in certain amount of water. Mixing both liquid produced CuI precipitate where then disolve in acetonitrile which resulting CuI solution. This solution then deposited in silicon and glass substrates by spin coating technique to make CuI thin film. In order to study further details of it crystalline behaviour, annealling temparature was conducted at 4 different stages which are as deposited, 50°, 100° and 150°. The results were examined by X-ray Diffraction (XRD) for their atoms arrangement within CuI crystalline, Scanning Electron Microscope (SEM) for surface morphology and Energy dispersive X-ray spectroscopy (EDXS) for chemical characterization. Results showed that the chemical compound tested were purely copper iodide element.

ABSTRACT The effect of crystalline size of ZnO thin film towards it electrical properties was con... more ABSTRACT The effect of crystalline size of ZnO thin film towards it electrical properties was conducted and studied. Through the process of sol gel method, ZnO solution was afforded by dissolving zinc acetate dehydrate as precursor into 2-methoxyethanol as solvent and added monoethanolmine as chelating agent. This solution was then deposited onto silicon substrates to produced thin film by spin coating technique. Following the work objective, produced thin film was sintered at different temperature to analyze it grain size against the properties of electrical. Scanning electron microscopy (SEM) was used to find any enhancement in grain size of ZnO. SEM results were supported with full width at half maximum (FWHM) values that proved the ZnO grain size improved with increasing temperature. For it electrical properties, current-voltage (I-V) measurement was conducted and it showed some progress in it results.

Influence of ligand to structural and optical properties of CuI thin film has been examined. CuI ... more Influence of ligand to structural and optical properties of CuI thin film has been examined. CuI thin film has been prepared by sol-gel process with incorporation of bidentate ligand into the CuI solution. Particles size of the solution is measured after few hours of stirred. Then, the thin film was formed by spin coating technique with appropriate parameters. It optical

The work presented here shows the effect of annealing temperature on CuI thin films. The 0.05 mol... more The work presented here shows the effect of annealing temperature on CuI thin films. The 0.05 mol of CuI solution is prepared at room temperature and then deposited in silicon and glass substrate. The CuI thin films were deposited using sol-gel spin coating method. The electrical, optical properties and surface morphology was characterized by current-voltage (I-V) measurement, ultraviolet-visible (UV-VIS) measurement

Particle size of the solution is measured after few hours of stirring. Then, the thin film was de... more Particle size of the solution is measured after few hours of stirring. Then, the thin film was deposited by spin coating technique with appropriate parameters. The optical properties of the composite thin film have been examined to display the energy shifting, which support the improved band gap compared to that of the pure CuI film, while the electrical properties show improved conductivity of the hole conductor to be a function of the p-type semiconductor for DSSC. This result indicates that the electrical and optical properties of CuI film can be easily adjusted by the formation of composite film with proper ligand agents.

ABSTRACT Solid state dye-sensitized solar cells (DSSCs) were first reported in 1991 without emplo... more ABSTRACT Solid state dye-sensitized solar cells (DSSCs) were first reported in 1991 without employing p-type as hole conductor. The p-type as hole conductor was first introduced in 1995 and CuI is preferred among others p-type semiconductors. However, in 2003 utilizing of CuI based DSSC was found unstable by the excessive iodine strongly decreased the photocurrent of the cell. Later then, the stability of CuI based DSSCs was reported can be improved by added small amount of triethylamine hydrothiocyanate (THT) in the CuI coating solution. Following to that, in this work new chemical is introduce as an option to present situation which can give equally or better effective for fabrication of solid-state DSSCs. The chemical is called tetramethylethylenediamine (TMED), is employed to CuI in sol-gel process and their characterizations have been studied. The CuI coating solution was prepared by dissolved CuI powder with acetonitrile and added in 0.5mL TMED. Using spin coating technique the sol then deposited onto glass and silicon substrate at room temperature. The film were analyzed by their particles conductivity using pH meter, surface morphology using Field Emission Scanning Electron Microscope (FE-SEM) and optical properties using ultraviolet visible spectroscopy (UV-Vis) and photoluminescence (PL) measurement. The results of this sol-gel were compared with other CuI sol-gel which prepared by dissolved CuI powder with acetonitrile only. The optical transmittance within ultra-violet range exhibited that thin film is transparent and it optical band gap have been studied. Further clarification and measurements need to be done in order to prove that the proposed chemical can be used as an option.

Nanotechnology, 2015

Working electrode (WE) fabrication offers significant challenges in terms of achieving higheffici... more Working electrode (WE) fabrication offers significant challenges in terms of achieving highefficiency dye-sensitized solar cells (DSCs). We have combined the beneficial effects of vertical nanorods grown on conducting glass substrate for charge transport and mesoporous particles for dye loading and have achieved a high photoconversion efficiency of (η) > 11% with an internal quantum efficiency of ∼93% in electrode films of thickness ∼7 ± 0.5 μm. Controlling the interface between the vertical nanorods and the mesoporous film is a crucial step in attaining high η. We identify three parameters, viz., large surface area of nanoparticles, increased light scattering of the nanorod-nanoparticle layer, and superior charge transport of nanorods, that simultaneously contribute to the improved photovoltaic performance of the WE developed.

Journal of Alloys and Compounds, 2014

ABSTRACT Zinc oxide (ZnO) thin films have been deposited onto glass substrates at various deposit... more ABSTRACT Zinc oxide (ZnO) thin films have been deposited onto glass substrates at various deposition speeds by a sonicated sol-gel dip-coating technique. This work studies the effects of deposition speed on the crystallisation behaviour and optical and electrical properties of the resulting films. X-ray diffraction (XRD) analysis showed that thin films were preferentially oriented along the (0 0 2) c-axis direction of the crystal. The transformation sequence of strain and stress effects in ZnO thin films has also been studied. The films deposited at a low deposition speed exhibited a large compressive stress of 0.78 GPa, which decreased to 0.43 GPa as the deposition speed increased to 40 mm/min. Interestingly, the enhancement in the crystallinity of these films led to a significant reduction in compressive stress. All films exhibited an average transmittance of greater than 90% in the visible region, with absorption edges at ∼380 nm. The photoluminescence (PL) measurements indicated that the intensity of the emission peaks varied significantly with deposition speed. The optical band gap energy (Eg) was evaluated as 3.276–3.289 eV, which increased with decreasing compressive stress along the c-axis. The energy band gap of the resulting ZnO films was found to be strongly influenced by the preferred c-axis (0 0 2) orientation.

IOP Conference Series: Materials Science and Engineering, 2011

... the figure, the absorption value of CuI thin film prepared with TMED started to seen at 350 n... more ... the figure, the absorption value of CuI thin film prepared with TMED started to seen at 350 nm which is almost close to the TUPAC plot (not ... valence band and sub energy levels in the conduction band [2][3]. This blue shift transition could be due to the existing of nano-particles in ...

Energy efficiency (EE) of wireless telecommunications has become a new challenge for the research... more Energy efficiency (EE) of wireless telecommunications has become a new challenge for the research community, governments and industries in order to reduce CO2 emission and operational costs. EE of base stations (BSs) in cellular networks is a growing concern for cellular operators to not only
maintain profitability, but also to reduce the overall negative impact to the environment and economic issues for wireless network operators. In this paper, a framework focuses on the Area Energy Efficiency (AEE) evaluation of LTE BSs is presented. The parameters affect on the AEE and the coverage area of LTE BS in different scenarios are investigated. AEE analysis has been done using a few key performance indicators including transmit power, bandwidth, load factor with the assumption of different scenarios (urban, suburban and rural). The simulation results show that the LTE BSs have better AEE in an urban environment for cell radius less than 750 m compare with the suburban and rural environments. Furthermore, it is obvious that there is a strong influence of traffic load, BW and transmission power on AEE of LTE network. On the other hand, AEE increases significantly as the BW size increases. Finally, it has been shown that the AEE of LTE macro BS decreases with increasing the percentage of traffic load for all scenarios.