Akram Aqili | The Hashemite University (original) (raw)
Papers by Akram Aqili
Computational Condensed Matter, Mar 1, 2023
The II-VI compound semiconductor thin films (CdS, ZnTe and ZnSe) have been prepared by different ... more The II-VI compound semiconductor thin films (CdS, ZnTe and ZnSe) have been prepared by different methods such as electron beam vacuum evaporation, closed space sublimation and two-sourced thermal evaporation. The effects of deposition parameters are discussed in detail, structural, optical and electrical properties have been studied. In spite of that the main goal is to get comparatively high electrical conductivity of the films, the optical properties of the films were also very important from the application point of view. For reducing the resistivity of II-VI group semiconductor thin films, doping with different materials were performed using an ion exchange method. These films have been doped with (Cu, Ag) dopant to make it p-type. The ion exchange parameters such as solution temperature, concentration and immersion time, and its effect on the speed of the process and further on the status of the resulting films was carefully determined and analyzed. Also the effect of post heat treatment, on the physical properties and the composition of the resulting films are discussed in detail.
Proceedings of SPIE, Oct 10, 2012
ZnSe thin films were prepared by, simple low cost, closed space sublimation method (CSS). The sil... more ZnSe thin films were prepared by, simple low cost, closed space sublimation method (CSS). The silver doping was achieved by ion exchange process, i.e. immersing the films in low concentrated silver nitrate solution for different time periods and flowed by heated treatment in vacuum. The effect of silver concentration on the optical properties , such as refractive index, absorption coefficient and optical band gap, have been calculated from the normal transmission spectra in UV, Visible and NIR region. The structure of the films was studied by X-ray diffraction. The EDS attached to SEM was used to determine the composition of the films. The electrical resistivity, at room temperature, was also measured and it was reduced considerably as silver concentration increased.
Chalcogenide Letters, Feb 23, 2023
Zinc Telluride (ZnTe) films were prepared by the closed space sublimation (CSS) method. The effec... more Zinc Telluride (ZnTe) films were prepared by the closed space sublimation (CSS) method. The effect of chemical treatments with concentrated phosphoric acid, on the optical, electric and structural properties of the films was studied. Zinc-blend structure of the polycrystalline nature of the films was confirmed by x-ray diffraction (XRD) spectra. The energy dispersive x-ray (EDX) shows an increase in Te ratio on the surface of the film as exposed to phosphoric acid. In addition, the dc electrical resistivity of the films was dropped considerably. The refractive index, thickness, and thickness irregularity of the films were determined by fitting of the optical transmittance spectra in the wavelength range 400 to 2500 nm. The effect, of treatment, on the optical parameters is also reported.
Journal of Alloys and Compounds, Apr 1, 2012
ZnTe thin films were deposited by closed space sublimation (CSS) technique on amorphous glass sub... more ZnTe thin films were deposited by closed space sublimation (CSS) technique on amorphous glass substrate. The deposited films were immersed in AgNO 3 solution for different time periods, then heated in vacuum. The resistivity of the film, immersed for 30 min, was reduced by less than six orders of magnitudes. The films structures were characterized by X-ray diffraction (XRD). Atomic force microscope (AFM) was used to detect the surface morphology of the films. The films thickness, the optical properties, such as refractive index, absorption coefficient and the optical band gap were determined from transmittance spectra in the wavelength range of 400-2500 nm. The dark electrical conductivities of the films were studied as function of temperature to determine the conductivity activation energy.
Applied Surface Science, Oct 1, 2000
Types IIVI compounds present a wide range of optical and electrical properties, making them an i... more Types IIVI compounds present a wide range of optical and electrical properties, making them an important class of material-competing candidates for silicon and other materials in photovaltic conversion and optoelectronic applications. It is well-known that the structure and other ...
Physics of the Solid State, 2021
The ionic and dielectric behavior of (AgPO 3) (1-x)-NaI x (x = 0, 0.02, 0.04, …, 0.14) systems we... more The ionic and dielectric behavior of (AgPO 3) (1-x)-NaI x (x = 0, 0.02, 0.04, …, 0.14) systems were tested in the frequency range of 1-10 6 Hz at different temperatures using impedance spectroscopy technique. Samples were prepared using the melt quenching method to obtain the desired ratios between NaI and AgPO 3. Results of impedance measurements showed a switching from resistive-like (at low frequency) to capacitive-like (at higher frequency) behavior with a single relaxation peak that shifts to higher frequency with increasing either the temperature or the dopant concentration. In addition, the Nyquist plots showed a decrease in the values of the bulk resistance of the samples with increasing temperature and dopant concentration. The measured AC-conductivity shows a cross-over at frequency f > 10 5 Hz. The conductivity shows an increase as function of temperature regardless the frequency range and it is almost constant at low frequency up to the crossover frequency, in addition to that, the power law dispersive behavior was also observed at higher frequency (f > 10 5 Hz). The DC-conductivity can be explained in terms of silver ions successful diffusion process that take place due to the applied alternative electric field. On the other hand, the diffusion controlled relaxation (DCR) model can be used to explain the power law conductivity. Finally, the values of the activation energy calculated from the linear plot of Arrhenius equation were found to decrease with the dopant concentration from 0.65 eV at zero concentration to 0.36 eV at 14% concentration.
Instrumentation Science & Technology, 2015
CdS thin films are widely used as the window material [1] in several thin film solar cells and ha... more CdS thin films are widely used as the window material [1] in several thin film solar cells and have been regarded as a prime candidate [2] for solar cell fabrication. Its ideal band gap, high optical absorption, and relative ease of deposition have made CdS especially attractive for the preparation of thin film solar cells. CdS is photoconductive material used for different applications, such as thin film FET transistors, X-ray detectors [3], photodiodes for solar-meters, photocatalytical solar energy stocking [4] etc.
Applied Surface Science, Aug 1, 2001
ZnTe thin films, prepared by two-sourced evaporation of zinc and tellurium, were immersed in Cu(N... more ZnTe thin films, prepared by two-sourced evaporation of zinc and tellurium, were immersed in Cu(NO 3) 2-H 2O solution for different time periods. The sheet resistance drastically decreased due to Cu diffusion in the films. Structure of the films is studied by X-ray diffraction (XRD), while the optical properties, such as film thickness, refractive index, absorption coefficient and optical band gap have been calculated from the normal transmission spectra in the range 400-2000 nm.
Thin Film Solar Technology IV, 2012
ABSTRACT ZnSe thin films were prepared by, simple low cost, closed space sublimation method (CSS)... more ABSTRACT ZnSe thin films were prepared by, simple low cost, closed space sublimation method (CSS). The silver doping was achieved by ion exchange process, i.e. immersing the films in low concentrated silver nitrate solution for different time periods and flowed by heated treatment in vacuum. The effect of silver concentration on the optical properties , such as refractive index, absorption coefficient and optical band gap, have been calculated from the normal transmission spectra in UV, Visible and NIR region. The structure of the films was studied by X-ray diffraction. The EDS attached to SEM was used to determine the composition of the films. The electrical resistivity, at room temperature, was also measured and it was reduced considerably as silver concentration increased.
Vacuum, 2005
Two-sourced evaporation technique is used to prepare hard ZnSe films by controlling the evaporati... more Two-sourced evaporation technique is used to prepare hard ZnSe films by controlling the evaporation rates of both Zn and Se at substrate temperature of 400 1C. The films are doped with Cu by immersion in the Cu(NO 3 ) 2 -H 2 O solution for different periods of time. The XRD has not shown a drastic change in the film structure while the electrical resistivity of the deposited film dropped from 10 9 O-cm to about 1.6 O-cm for solution immersed films after heat treatment. Optical properties of deposited and doped films, such as film thickness, absorption coefficient and optical band gap have been calculated from the normal transmission spectra in the range of 300-2200 nm.
Semiconductor Science and Technology, 2006
Cadmium telluride (CdTe) thin films were deposited onto scratch-free transparent glass substrates... more Cadmium telluride (CdTe) thin films were deposited onto scratch-free transparent glass substrates by the two-source evaporation technique, using Cd and Te as two different evaporants. In the next step, films were heated under vacuum at 500 • C for 1 h and dipped in Cu(NO 3 ) 2 -H 2 O solution at room temperature. These films were again heated under vacuum for 1 h at 500 • C to obtain maximum Cu diffusion. The samples were characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM), optically by a Lambda 900 UV/VIS/NIR spectrophotometer and electrically, i.e. dc electrical resistivity, by the van der Pauw method at room temperature, dark conductivity, and activation energy analysis as a function of temperature by the two-probe method under vacuum. The EDX results showed an increase of Cu content in the samples by increasing the immersion time of the CdTe films in the solution. The layer thickness of diffused Cu atoms in CdTe is determined by comparing the difference of absorption between as-deposited and immersed films with the absorption graph of Cu films of varying thicknesses.
Computational Condensed Matter, Mar 1, 2023
The II-VI compound semiconductor thin films (CdS, ZnTe and ZnSe) have been prepared by different ... more The II-VI compound semiconductor thin films (CdS, ZnTe and ZnSe) have been prepared by different methods such as electron beam vacuum evaporation, closed space sublimation and two-sourced thermal evaporation. The effects of deposition parameters are discussed in detail, structural, optical and electrical properties have been studied. In spite of that the main goal is to get comparatively high electrical conductivity of the films, the optical properties of the films were also very important from the application point of view. For reducing the resistivity of II-VI group semiconductor thin films, doping with different materials were performed using an ion exchange method. These films have been doped with (Cu, Ag) dopant to make it p-type. The ion exchange parameters such as solution temperature, concentration and immersion time, and its effect on the speed of the process and further on the status of the resulting films was carefully determined and analyzed. Also the effect of post heat treatment, on the physical properties and the composition of the resulting films are discussed in detail.
Proceedings of SPIE, Oct 10, 2012
ZnSe thin films were prepared by, simple low cost, closed space sublimation method (CSS). The sil... more ZnSe thin films were prepared by, simple low cost, closed space sublimation method (CSS). The silver doping was achieved by ion exchange process, i.e. immersing the films in low concentrated silver nitrate solution for different time periods and flowed by heated treatment in vacuum. The effect of silver concentration on the optical properties , such as refractive index, absorption coefficient and optical band gap, have been calculated from the normal transmission spectra in UV, Visible and NIR region. The structure of the films was studied by X-ray diffraction. The EDS attached to SEM was used to determine the composition of the films. The electrical resistivity, at room temperature, was also measured and it was reduced considerably as silver concentration increased.
Chalcogenide Letters, Feb 23, 2023
Zinc Telluride (ZnTe) films were prepared by the closed space sublimation (CSS) method. The effec... more Zinc Telluride (ZnTe) films were prepared by the closed space sublimation (CSS) method. The effect of chemical treatments with concentrated phosphoric acid, on the optical, electric and structural properties of the films was studied. Zinc-blend structure of the polycrystalline nature of the films was confirmed by x-ray diffraction (XRD) spectra. The energy dispersive x-ray (EDX) shows an increase in Te ratio on the surface of the film as exposed to phosphoric acid. In addition, the dc electrical resistivity of the films was dropped considerably. The refractive index, thickness, and thickness irregularity of the films were determined by fitting of the optical transmittance spectra in the wavelength range 400 to 2500 nm. The effect, of treatment, on the optical parameters is also reported.
Journal of Alloys and Compounds, Apr 1, 2012
ZnTe thin films were deposited by closed space sublimation (CSS) technique on amorphous glass sub... more ZnTe thin films were deposited by closed space sublimation (CSS) technique on amorphous glass substrate. The deposited films were immersed in AgNO 3 solution for different time periods, then heated in vacuum. The resistivity of the film, immersed for 30 min, was reduced by less than six orders of magnitudes. The films structures were characterized by X-ray diffraction (XRD). Atomic force microscope (AFM) was used to detect the surface morphology of the films. The films thickness, the optical properties, such as refractive index, absorption coefficient and the optical band gap were determined from transmittance spectra in the wavelength range of 400-2500 nm. The dark electrical conductivities of the films were studied as function of temperature to determine the conductivity activation energy.
Applied Surface Science, Oct 1, 2000
Types IIVI compounds present a wide range of optical and electrical properties, making them an i... more Types IIVI compounds present a wide range of optical and electrical properties, making them an important class of material-competing candidates for silicon and other materials in photovaltic conversion and optoelectronic applications. It is well-known that the structure and other ...
Physics of the Solid State, 2021
The ionic and dielectric behavior of (AgPO 3) (1-x)-NaI x (x = 0, 0.02, 0.04, …, 0.14) systems we... more The ionic and dielectric behavior of (AgPO 3) (1-x)-NaI x (x = 0, 0.02, 0.04, …, 0.14) systems were tested in the frequency range of 1-10 6 Hz at different temperatures using impedance spectroscopy technique. Samples were prepared using the melt quenching method to obtain the desired ratios between NaI and AgPO 3. Results of impedance measurements showed a switching from resistive-like (at low frequency) to capacitive-like (at higher frequency) behavior with a single relaxation peak that shifts to higher frequency with increasing either the temperature or the dopant concentration. In addition, the Nyquist plots showed a decrease in the values of the bulk resistance of the samples with increasing temperature and dopant concentration. The measured AC-conductivity shows a cross-over at frequency f > 10 5 Hz. The conductivity shows an increase as function of temperature regardless the frequency range and it is almost constant at low frequency up to the crossover frequency, in addition to that, the power law dispersive behavior was also observed at higher frequency (f > 10 5 Hz). The DC-conductivity can be explained in terms of silver ions successful diffusion process that take place due to the applied alternative electric field. On the other hand, the diffusion controlled relaxation (DCR) model can be used to explain the power law conductivity. Finally, the values of the activation energy calculated from the linear plot of Arrhenius equation were found to decrease with the dopant concentration from 0.65 eV at zero concentration to 0.36 eV at 14% concentration.
Instrumentation Science & Technology, 2015
CdS thin films are widely used as the window material [1] in several thin film solar cells and ha... more CdS thin films are widely used as the window material [1] in several thin film solar cells and have been regarded as a prime candidate [2] for solar cell fabrication. Its ideal band gap, high optical absorption, and relative ease of deposition have made CdS especially attractive for the preparation of thin film solar cells. CdS is photoconductive material used for different applications, such as thin film FET transistors, X-ray detectors [3], photodiodes for solar-meters, photocatalytical solar energy stocking [4] etc.
Applied Surface Science, Aug 1, 2001
ZnTe thin films, prepared by two-sourced evaporation of zinc and tellurium, were immersed in Cu(N... more ZnTe thin films, prepared by two-sourced evaporation of zinc and tellurium, were immersed in Cu(NO 3) 2-H 2O solution for different time periods. The sheet resistance drastically decreased due to Cu diffusion in the films. Structure of the films is studied by X-ray diffraction (XRD), while the optical properties, such as film thickness, refractive index, absorption coefficient and optical band gap have been calculated from the normal transmission spectra in the range 400-2000 nm.
Thin Film Solar Technology IV, 2012
ABSTRACT ZnSe thin films were prepared by, simple low cost, closed space sublimation method (CSS)... more ABSTRACT ZnSe thin films were prepared by, simple low cost, closed space sublimation method (CSS). The silver doping was achieved by ion exchange process, i.e. immersing the films in low concentrated silver nitrate solution for different time periods and flowed by heated treatment in vacuum. The effect of silver concentration on the optical properties , such as refractive index, absorption coefficient and optical band gap, have been calculated from the normal transmission spectra in UV, Visible and NIR region. The structure of the films was studied by X-ray diffraction. The EDS attached to SEM was used to determine the composition of the films. The electrical resistivity, at room temperature, was also measured and it was reduced considerably as silver concentration increased.
Vacuum, 2005
Two-sourced evaporation technique is used to prepare hard ZnSe films by controlling the evaporati... more Two-sourced evaporation technique is used to prepare hard ZnSe films by controlling the evaporation rates of both Zn and Se at substrate temperature of 400 1C. The films are doped with Cu by immersion in the Cu(NO 3 ) 2 -H 2 O solution for different periods of time. The XRD has not shown a drastic change in the film structure while the electrical resistivity of the deposited film dropped from 10 9 O-cm to about 1.6 O-cm for solution immersed films after heat treatment. Optical properties of deposited and doped films, such as film thickness, absorption coefficient and optical band gap have been calculated from the normal transmission spectra in the range of 300-2200 nm.
Semiconductor Science and Technology, 2006
Cadmium telluride (CdTe) thin films were deposited onto scratch-free transparent glass substrates... more Cadmium telluride (CdTe) thin films were deposited onto scratch-free transparent glass substrates by the two-source evaporation technique, using Cd and Te as two different evaporants. In the next step, films were heated under vacuum at 500 • C for 1 h and dipped in Cu(NO 3 ) 2 -H 2 O solution at room temperature. These films were again heated under vacuum for 1 h at 500 • C to obtain maximum Cu diffusion. The samples were characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM), optically by a Lambda 900 UV/VIS/NIR spectrophotometer and electrically, i.e. dc electrical resistivity, by the van der Pauw method at room temperature, dark conductivity, and activation energy analysis as a function of temperature by the two-probe method under vacuum. The EDX results showed an increase of Cu content in the samples by increasing the immersion time of the CdTe films in the solution. The layer thickness of diffused Cu atoms in CdTe is determined by comparing the difference of absorption between as-deposited and immersed films with the absorption graph of Cu films of varying thicknesses.