Mohammed salah M S AIDA (original) (raw)

Papers by Mohammed salah M S AIDA

In the present work, we have studied the effect of metal back contact nature on the electrical pr... more In the present work, we have studied the effect of metal back contact nature on the electrical properties of CZTS/ZnS based heterojunction prepared by spray pyrolysis. Three different back contact metals (Al, Au and Ag) were tested as alternative of the commonly used Molybdenum. Structural and optical properties of different layers are characterized. The electrical devices characterization were achieved by (I-V) at ambient and at different temperatures and capacitance-conductance vs frequency (C-G-f) measurements. The realized structures exhibit a rectifying behavior. The ideality factor of all devices were found to be large, it is found equal to 5.9 when using Au contact and equal to 10.5 and 11.4 in heterojunction prepared with Ag and Al back contact respectively. The anomalous ideality factor is due to the Schottky contact between Al, Ag and CZTS and to the presence of density of defect at the interface CZTS/ZnS. The latter was estimated from conductance measurement as a function of frequency and found equal to 10 10 cm −2 eV −1. From this study we inferred that Au contact can be an alternative of Mo as back contact of CZTS based solar cell.

In the present work, Cu 2 ZnSnS 4 (CZTS) thin films were deposited by spray pyrolysis, the effect... more In the present work, Cu 2 ZnSnS 4 (CZTS) thin films were deposited by spray pyrolysis, the effect of zinc molarity on films structural, optical and electrical properties was investigated. CZTS films were grown by pneumatic spray pyrolysis with various zinc salt molarities. The structural properties reveal that all prepared CZTS films have a kesterite structure with a preferential orientation along (112) plan with the presence of secondary phases. Film composition and structural property vary with Zn molarity: at relatively low Zn molarity CuS secondary phase is formed, while with increasing Zn molarity ZnS secondary phase is formed. The crystallite size increases from 25 to 125 nm with increasing Zn molarity. Films transmission spectra show low transmission in the visible range, whereas the band gaps varies slightly with Zn salt molarity, it lies between 1.3 and 1.37 eV. Hall Effect measurements were employed to determine the electrical properties of CZTS films. The films conductivity is a p type, it is reduced with increasing Zn molarity due to the reduction of free carriers concentration caused by carriers loss at ZnS/CZTS interface and the presence of the resistive ZnS phase.

Proceedings of the Institution of Mechanical Engineers, Part N: Journal of Nanoengineering and Nanosystems, 2009

In the present work, zinc oxide (ZnO) thin films are deposited by the ultrasonic spray method. In... more In the present work, zinc oxide (ZnO) thin films are deposited by the ultrasonic spray method. In order to study the influence of the nature of the precursor solution, zinc acetate and zinc nitrate salts dissolved in methanol are used respectively to prepare two non-aqueous starting solutions. The influence of substrate temperature on the structural growth kinetics and optical properties of ZnO films is also investigated. For this purpose, the substrate temperature is varied in the range of 250—400°C. X-ray diffraction (XRD) analysis reveals that at low temperature the films that are grown contain nanocrystallites with a privileged orientation depending on the nature of the starting precursor; these privileged orientations correspond to the plane (100) for the films deposited with zinc acetate and (002) for films prepared with zinc nitrate precursor. However, with increasing deposition temperature, the privileged orientation disappears. The growth kinetics is closely related to the ...

EPJ Web of Conferences, 2013

in this work, we report the transparent pure and Sn-doped zinc oxide (ZnO). The films were deposi... more in this work, we report the transparent pure and Sn-doped zinc oxide (ZnO). The films were deposited onto microscope glass substrate which was heated at 350±5C° by ultrasonic spray pyrolysis (U S P) deposition technique. The concentrations of Sn were selected within the range of 0-3% by step of 0.5% and the time deposition is kept at 5 min. A (002)-oriented wurtzite crystal structure was confirmed by X-rays patterns; and grain size varied within the range 7.37-14.84nm, and cristanillity is calculated goes from14.4 to 45.9%. Based on UV-VIS-IR analysis, the results revealed the high transparency of the sprayed films which exceeds 90%. The band gap energy was of 3.26-3.30 eV. The film thickness was estimated by spectroscopy ellipsometry and the found values were of 165-270nm. The refractive index is in the range of 2.75.The obtained electrical parameters were around 10 18 cm-3 , 3.6 cm²/Vs, 1.6Ω.cm; 5.8cm 3 /C. finally the Sn-doping has influenced the physical parameters of asground ZnO films

Journal of Materials Science, 2009

The purpose of this work is to deposit the CuInSe2 films on the ITO substrate by electrodepositio... more The purpose of this work is to deposit the CuInSe2 films on the ITO substrate by electrodeposition technique using a simplified two electrodes system and to investigate the effect of ITO sheet resistance on the fundamental properties of the resulting films. The as deposited films were annealed under argon atmosphere at 300 °C during 30 min. The structural, morphological and electrical properties

Journal of Alloys and Compounds, 2012

Cu 2 ZnSnS 4 (CZTS) thin films were deposited by ultrasonic spray pyrolysis technique. The substr... more Cu 2 ZnSnS 4 (CZTS) thin films were deposited by ultrasonic spray pyrolysis technique. The substrate temperature was varied from 280 to 360°C in order to investigate its influence on CZTS films properties. The deposition rate shows two activation energies 0.16 and 0.53 eV, respectively at low and high substrate temperatures. This indicates that CZTS deposition by spray pyrolysis passes by two different processes with increasing temperature substrate. The temperature 320°C corresponds to the transition between these two processes. The X rays diffraction (XRD) analysis indicated that the deposited films have a kesterite hexagonal structure with (1 1 2) preferential orientation and a crystalline size, ranged from 30 to 52 nm with increasing substrate temperature. Stannate ZnSnO 3 is present as a secondary phase. The presence of this secondary phase causes films optical band broadening. Broad emissions at around 1.27 eV was observed in the photoluminescence spectrum measured at 77 K, it is accompanied with a small peak located at 1.75 eV due the presence of zinc stannate phase ZnSnO 3 .

Semiconductor Science and Technology, 2009

ZnO films were prepared using the simple, flexible and cost-effective spray pyrolysis technique a... more ZnO films were prepared using the simple, flexible and cost-effective spray pyrolysis technique at different substrate temperatures and precursor molarity values. The films' structural, optical and electrical properties were investigated by x-ray diffraction, UV-VIS transmittance spectroscopy, profilometry and voltage-current-temperature (VIT) measurements. The films prepared at substrate temperatures above 400 • C appear better crystallized with (0 0 2) preferred orientation and exhibit higher visible transmittance (65-80%), higher electrical n-type semiconductor conductivity (10-50 (cm) −1), lower activation energy (<0.35 eV) and smaller Urbach energy (80 meV). These results indicate that such sprayed ZnO films are chemically purer and have many fewer defects and less disorder owing to an almost complete chemical decomposition of the precursor droplets. ZnO films having desired optical and electrical properties for cheaper large-area solar cells may thus be tailored through the substrate temperature and the precursor molarity.

Materials Science in Semiconductor Processing, 2015

Abstract It is known that the quality of the diode and the transport of the charge carriers acros... more Abstract It is known that the quality of the diode and the transport of the charge carriers across the junction may be greatly influenced by the quality of the interface, and depends on the crystallinity of thin layers. In this work, we have prepared the p-CuO/n-ZnO and p-CuO/n-ZnS hetero-junctions by ultrasonic spray pyrolysis at 300 °C under atmospheric pressure. We have investigated the influence of the thickness of CuO film on the electrical properties of the hetero-junctions. The X-ray diffraction indicates that both the CuO and ZnO thin films grow according to polycrystalline nature while ZnS films show a quasi-amorphous nature. The current voltage temperature ( I – V – T ) and capacitance voltage ( C – V ) characteristics reveal that CuO/ZnS is an abrupt junction, whereas the data of CuO/ZnO hetero-junctions suggest that the potential barrier heights are spatially non-uniform (junction not abrupt). The electrical behavior of the junction is strongly affected by the defect state distribution at the hetero-interface. The recombination process involving the interface states predominates at low forward bias ( V V >0.5 V) on the thin CuO side. The junction parameters (ideality factor, rectification ratio, built in potential etc…) are of the same order of magnitude for both heterojunction diodes i.e. ZnO/CuO and ZnS/CuO.

Bulletin of Materials Science, 2014

CuInSe 2 thin films were prepared by one-step electrodeposition process using a simplified twoele... more CuInSe 2 thin films were prepared by one-step electrodeposition process using a simplified twoelectrodes system. The films were deposited, during 5, 10, 15 and 20 min, from the deionized water solution consisting of CuCl 2, InCl 3 and SeO 2 onto ITO-coated glass substrates. As-deposited films have been annealed under vacuum at 300 °C during 30 min. The structural, optical band gap and electrical resistivity of elaborated films were studied, respectively, using X-ray diffraction (XRD), Raman spectroscopy, UV spectrophotometer and four-point probe method. The micro structural parameters like lattice constants, crystallite size, dislocation density and strain have been evaluated. The XRD investigation proved that the film deposited at 20 min present CuInSe 2 single phase in its chalcopyrite structure and with preferred orientation along (1 1 2) direction, whereas the films deposited at 5, 10 and 15 min show the CuInSe 2 chalcopyrite structure with the In 2 Se 3 as secondary phase. We have found that the formation mechanism of CuInSe 2 depends on the In 2 Se 3 phase. The optical band gap of the films is found to decrease from 1⋅17 to 1⋅04 eV with increase in deposition time. All films show Raman spectra with a dominant A 1 mode at 174 cm-1 , confirming the chalcopyrite crystalline quality of these films. The films exhibited a range of resistivity varying from 2.3 × 10-3 to 4.4 × 10-1 Ω cm.

Materials Science in Semiconductor Processing, 2013

ABSTRACT The present work is devoted to the preparation of zinc oxide (ZnO): tin oxide (SnO2) thi... more ABSTRACT The present work is devoted to the preparation of zinc oxide (ZnO): tin oxide (SnO2) thin films by ultrasonic spray technique. A set of films are deposited using a solution formed with zinc acetate and tin chloride salts mixture with varied weight ratio R=[Sn/(Zn+Sn)]. The ratio R is varied from 0 to 100% in order to investigate the influence of Sn concentration on the physical properties of ZnO:SnO2 films. The X rays diffraction (XRD) analysis indicated that films are composed of ZnO and SnO2 distinct phases without any alloys or spinnel phase formations. The average grain size of crystallites varies with the ratio R from 17 to 20 nm for SnO2 and from 24 to 40 nm for ZnO. The obtained films are highly transparent with a transmission coefficient equal to 80%. An increase in Sn concentration increases both the effective band gap energy from 3.2 to 4.01 eV and the photoluminescence intensity peak assigned defects to SnO2. The films electrical characterization indicated that films are resistive. Their resistivities vary between 1.2 x 10(2) and 3.3 x 10(4) (Omega cm). The higher resistivity is measured in film deposited with a ratio R equal to 50%.

Thin Solid Films, 2014

ABSTRACT In the present work, polycrystalline transparent conductive aluminium doped zinc oxide (... more ABSTRACT In the present work, polycrystalline transparent conductive aluminium doped zinc oxide (ZnO:Al) films, have been grown on glass and silicon substrates by radio frequency magnetron sputtering technique at room temperature. The effect of oxygen content in the fed gas, on the structural, optical and electrical film properties was investigated. We found that film growth rate decreases with increasing oxygen content. The crystalline of ZnO:Al films deposited on glass substrates has an hexagonal structure with a preferential orientation along the c-axis. While for films deposited on silicon substrates, the crystallites preferred orientation shifts gradually from (002) to (100) direction as the oxygen content increases. While near stress-free film was obtained at 0% O2 content, intrinsic stress also increases with the oxygen content. Low resistivity (ρ = 1.25 × 10− 3 Ω cm) associated with high transmittance (T > 92%) in the visible regions was measured in ZnO:Al film deposited at room temperature with no oxygen in the deposition chamber. The optical characterization indicated that the band gap shifts towards lower energies with increasing oxygen content.

Solid State Communications, 2001

The thermal conductivity of amorphous silicon thin ®lms is measured in one dimension steady state... more The thermal conductivity of amorphous silicon thin ®lms is measured in one dimension steady state condition. The experimental method is based on heating the sample front surface and monitoring the temperatures at its two sides. The experiments were carried out in conditions ensuring one-direction heat¯ow from top to bottom throughout the sample thickness. Sputtered a-Si:H ®lms prepared with different conditions are used in order to investigate the dependence of thermal conductivity on material properties (i.e. hydrogen content and microstructure). The results show that, ®rstly, amorphous silicon is a very bad thermal conductor material. Secondly, the disorder in the ®lm network plays an important role in thermal conduction. The highly disordered ®lm exhibits the lowest thermal conductivity.

Solid State Communications - SOLID STATE COMMUN, 2001

The thermal conductivity of amorphous silicon thin films is measured in one dimension steady stat... more The thermal conductivity of amorphous silicon thin films is measured in one dimension steady state condition. The experimental method is based on heating the sample front surface and monitoring the temperatures at its two sides. The experiments were carried out in conditions ensuring one-direction heat flow from top to bottom throughout the sample thickness. Sputtered a-Si:H films prepared with different conditions are used in order to investigate the dependence of thermal conductivity on material properties (i.e. hydrogen content and microstructure). The results show that, firstly, amorphous silicon is a very bad thermal conductor material. Secondly, the disorder in the film network plays an important role in thermal conduction. The highly disordered film exhibits the lowest thermal conductivity.

Philosophical Magazine Letters, 1997

... The rate of Ar ionization is increased by He dilution directly through the de-excitation of m... more ... The rate of Ar ionization is increased by He dilution directly through the de-excitation of metastable He atoms 122 MS Aida et al. Fig. ... REFERENCES Anderson, JC, and Biswas, S., 1985 J. non-crystalline Solids, 77 & 78, 817. Curtins H., Wyrsch, N., and Shah, A., 1987, Electron. ...

Materials Science in Semiconductor Processing, 2014

Tin Sulfide (SnS) thin films were deposited by ultrasonic spray pyrolysis technique, on glass sub... more Tin Sulfide (SnS) thin films were deposited by ultrasonic spray pyrolysis technique, on glass substrate heated at 280 1C, with different deposition times. The used precursor SnCl 2 and thiourea are dissolved in methanol. X-ray diffraction (XRD) analysis indicates that films are mainly composed with orthorhombic SnS phase at low deposition time. With increasing deposition time, the hexagonal SnS 2 phases become dominant. SnO 2 and metallic Sn phases have been detected with increasing deposition time. Scanning electron microscopy (SEM) observations reveal that films surfaces are rough with the presence of bubbles due to S 2 gas exo-diffusion from the bulk during film growth. A model of S 2 gas formation is presented.

Journal of Alloys and Compounds, 2011

ZnO thin films were deposited by ultrasonic spray technique, zinc acetate was used as starting so... more ZnO thin films were deposited by ultrasonic spray technique, zinc acetate was used as starting solution with a molarity of 0.1 M. A set of indium (In) doped ZnO (between 2 and 8 wt%) thin films were grown on glass substrate at 350 • C. The present work is focused on the influence of the doping level on the structural, optical and electrical films properties. Optical film characterization was carried by using UV-visible transmission spectroscopy, the optical gap was deduced from absorption. From X ray diffraction (XRD) analysis, we have deduced that ZnO films are formed with nanocrystalline structure with preferential (0 0 2) orientation. The grain size is increased with In doping from 28 to 37 nm. Electrical characterization was achieved using two-probes coplanar structure, the measured conductivity varies from 2.3 to 5.9 cm −1 when increasing the doping level. However the optical gap is reduced from 3.4 to 3.1 eV.

Journal of Alloys and Compounds, 2014

Abstract Polycrystalline chalcopyrite CuInSe2 (CIS) thin films were deposited by electrodepositio... more Abstract Polycrystalline chalcopyrite CuInSe2 (CIS) thin films were deposited by electrodeposition technique onto ITO coated glass substrates. The used bath solution is formed by dissolution of CuCl2, InCl3, and SeO2 salts in de-ionized water, where the [Se]/[Cu + In] molar ratio is ranged from 0.4 to 1.3. The deposited films have been annealed at 300 °C for 30 min in argon atmosphere. The films structure and surface morphology characterizations were carried out respectively by means of X-ray diffraction method (XRD) and scanning electron microscope (SEM). XRD results indicate that CIS films having single phase chalcopyrite are obtained when the [Se]/[Cu + In] molar ratio is less than 1.3. While, for [Se]/[Cu + In] = 1.3, CuSe secondary phase is present together with CIS chalcopyrite phase. The crystallites were found to have a preferred orientation along (1 1 2) direction. The UV–visible optical transmittance measurements show that films absorption is due to allowed direct transition with a band gap ranged from 1.04 to 1.2 eV.

Journal of the Korean Ceramic Society