Browsing by Author "Rahal, Achour"

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A comparative study on structural and optical properties of ZnO and Al-doped ZnO thin films obtained by ultrasonic spray method using different solvents
(Urban & Fischer, 2014-07-01) Gahtar, Abdelouahab; Rahal, Achour; Benhaoua, Boubaker; Benramache, Said
Abstract Transparent conducting ZnO and Al doped ZnO thin films were deposited on glass substrate by ultrasonic spray method. The thin films with concentration of 0.1 M were deposited at 350 °C with 2 min of deposition time. The effects of ethanol and methanol solution before and after doping on the structural, optical and electrical properties were examined. The DRX analyses indicated that ZnO films have nanocrystalline nature and hexagonal wurtzite structure with (1 0 0) and (0 0 2) preferential orientation corresponding to ZnO films resulting from methanol and ethanol solution, respectively. The crystallinity of the thin films improved with methanol solution after doping to (0 0 2) oriented. All films exhibit an average optical transparency about 90%, in the visible range. The band gaps values of ZnO thin films are increased after doping from 3.10 to 3.26 eV and 3.27 to 3.30 eV upon Al doping obtained by ethanol and methanol solution, respectively. The electrical conductivity increase from 7.5 to 15.2 (Ω cm)−1 of undoped to Al doped ZnO thin films prepared by using ethanol solution. However, for the methanol solution; the electrical conductivity of the film is stabilized after doping.
Effect of fluorine doping on the structural, optical and electrical properties of SnO2 thin films prepared by spray ultrasonic
(Superlattices and Microstructures, 2014-06) Benhaoua, Atmane; Rahal, Achour; Benhaoua, Boubaker; Jlassi, Mohamed
Abstract The undoped and fluorine doped tin oxide (SnO2) thin films are synthesized by using cost-effective spray ultrasonic technique; the films are sprayed on heated glass substrates at 480 °C. The dependence of structural, optical and electrical properties of SnO2 films on the concentration of fluorine is investigated. X-ray diffraction, Optical absorption, four-point probe and Hall Effect studies have been performed on undoped and fluorine doped SnO2 (FTO) films. X-ray diffraction pattern reveals the presence of cassiterite structure with (2 0 0) as preferential orientation for FTO films. The crystallite size varies from 10.3 to 27.12 nm and was affected by F concentration which was lying between 0 and 12 wt.%. All films exhibit optical transmission T(λ) more than 83.9% in visible region; the optically estimated film thickness varies from 700 to 975 nm for the same given time (3 min deposition) and band gap (Eg) varies from 3.651 to 3.902 eV. The electrical study reveals that the films have n-type electrical conductivity and depend upon fluorine concentration too. The sprayed FTO film doped at 6 wt.% has the minimum resistivity of 1.47 × 10−3 Ω cm and minimum resistance sheet (Rsh) of 21 Ω/cm2 whereas the carrier concentration and mobility were about 2.04 × 1019 cm−3 and 208.4 cm2 V−1 s−1 respectively.
Effect of iron doping on tin oxide thin films
(University of Eloued جامعة الوادي, 2018-12-10) Segueni, Leila; Benhaoua, Boubaker; Allag, Nassiba; Rahal, Achour; Benhaoua, Atmane
In this study, Undoped tin oxide (SnO2) and iron (Fe) doped tin oxide thin films were deposited on heated glass using spray pyrolysis technique. SnCl2 and FeCl3 were used as sources of SnO2 and Fe doping respectively. Effects of dopant on the optical, structural and opto-electrical properties of 0,0.2 and 0.4 wt.% Fe-doped SnO2 thin films were investigated. Optical transmittance spectra of the thin films showed high transparency of about 80-90% in visible region. The optical gap of 0,0.2and 0.4 wt. % Fe-doped SnO2 thin films were found to be in 3.78-3.67 eV range. X-ray diffraction patterns showed that both undoped SnO2 and Fe-doped SnO2 thin films, were polycrystalline with cassiterite tetragonal crystal structure. The preferential orientation for undoped SnO2 was along (211) plane whereas Fe-doped SnO2 preferential orientations were along (110) planes. The calculated grain sizes were in 35.63- 30.03 nm average. Fe-doped SnO2 thin films are promising to be used as smart windows , gas sensor and water treatment
The effects of solvent nature on spray-deposited ZnO thin film prepared from Zn (CH3COO)2, 2H2O
(Urban & Fischer, 2014-01-01) Benramache, Said; Rahal, Achour; Benhaoua, Boubaker
Transparent conducting zinc oxide was deposited on glass substrate by ultrasonic spray method. The ZnO samples with concentration of 0.1 M were deposited at 300, 350 and 400 °C with 2 min of deposition time. The effects of substrate temperature, ethanol and methanol solution on the structural, electrical and optical properties were examined. The DRX analyses indicated that ZnO films have polycrystalline nature and hexagonal wurtzite structure with (1 0 0) and (0 0 2) preferential orientation corresponding to ZnO films resulting from methanol and ethanol, respectively. The crystallinity of the thin films improved with ethanol solution. All films exhibit an average optical transparency about 80%, in the visible range. The band gap energy of ZnO films obtained with methanol solution higher than of ethanol solution for all the films. The electrical resistivity decrease with ZnO obtained from ethanol indicated; due to the maximum crystallite size retched at this point.
Elaboration des verres conducteurs par déposition de ZnO sur des verres ordinaires
(University of Eloued جامعة الوادي, 2013-01-10) Rahal, Achour
كان هذا العمل من الذاكرة للكائن السيطرة على تقنية رذاذ بالموجات فوق الصوتية لتطوير ودراسة خصائص الأغشية الرقيقة لأكسيد الزنك (ZnO) و SnO2 بالنظر إلى تطبيقاتها المحتملة. دراسة أساسية للمعايير الفيزيائية والكيميائية بما في ذلك تبلور المواد المودعة ، وشفافيتها في هيمنة الأشعة فوق البنفسجية المرئية ، ومؤشرات الانكسار وطاقات الفجوة. تتم دراسة هذه المعلمات كدالة لتركيز المنشطات ودرجات حرارة الركائز أثناء الترسب. أيضا كانت درجة حرارة الصلب معلمة أساسية في هذا العمل ل ZnO. وقد وجد أن الخصائص الهيكلية والبصرية لل ZnO تتأثر كدالة لل زيادة تركيز dopant من 0 إلى 3.5 ٪ ل ZnO وهذا جيد كانت درجة التبلور ، أي في الاتجاهات (100) و (101) و (102) و (002) ، عند درجة حرارة ترسب تصل إلى 350 درجة مئوية بالنسبة للمنشطات بنسبة 2.75 ٪. خضعت المعلمات الأخرى مثل المقاومة لنتائج التحسن نفسها تحت درجة حرارة الترسب هذه. تم العثور على طاقة فجوة ZnO التي تم تطويرها بواسطة هذه الطريقة لتكون في حدود 3.27 فولت للطبقة غير المتغيرة ومتغيرة ما بين 3.27 و 3.32 فولت ، اعتمادًا على المنشطات وتكشف عن تأثير Burstein -Moss. بالنسبة إلى SnO2 ، تبين أن الخواص الهيكلية والبصرية تتأثر وفقًا لزيادة تركيز المادة المنبثقة التي تتراوح من 0 إلى 10٪ في SnO2 وأن الصالح كانت درجة التبلور في الاتجاه (101) عند درجة حرارة ترسب قدرها 480 درجة مئوية بالنسبة للمنشطات بنسبة 5 ٪. يكون لأطياف الشفافية متوسط قيمة النفاذية Tmoy حوالي 82٪ في النطاق المرئي (400 نانومتر - 800 نانومتر) لغالبية الأفلام. أعطى امتصاص الشريط الشريطي للطبقة قيمة فجوة على سبيل المثال عند 4.05 فولت. Ce travail de mémoire avait pour objet la maîtrise de la technique Spray ultrasonique pour l’élaboration et l’étude des propriétés des couches minces de l’oxyde de zinc (ZnO) et SnO2 vu leurs potentiel d'applications. Une étude fondamentale de ses paramètres physico-chimiques notamment la cristallisation des matériaux déposés, leurs transparence dans le domine UV-visible, les indices de réfraction et les énergies de gap. Ces paramètres sont étudiés en fonction de la concentration des dopants et les températures des substrats lors de dépôt. Aussi la température de recuit était un paramètre essentiel dans ce travail pour le ZnO. Il est trouvé que les propriétés structurelles et optiques de ZnO sont affectées en fonction de l'augmentation de la concentration du dopant allant de 0 à 3, 5% pour le ZnO et que la bonne cristallisation, soit suivant les directions (100), (101), (102) et (002), était à une température de dépôt de l'ordre de 350°C pour un dopage de l’ordre 2,75%. Les autres paramètres comme la résistivité ont subit les mêmes résultats d'amélioration sous cette température de dépôt. L'énergie de gap de ZnO élaborés par cette méthode était trouvée de l’ordre de 3.27 eV pour la couche non dopé et variable entre 3.27 et 3,32 eV en fonction du dopage et révèle l’effet Burstein -Moss. Pour le SnO2 Il est trouvé que les propriétés structurelles et optiques sont affectées en fonction de l'augmentation de la concentration du dopant allant de 0 à 10% pour le SnO2 et que la bonne cristallisation suivant la direction (1O1) était à une température de dépôt de l'ordre de 480°C pour un dopage de l’ordre 5%. Les spectres de transparence ont une valeur de transmittance moyenne Tmoy autour de 82% dans le domaine du visible (400 nm – 800 nm) pour la majorité des films. L’absorption bande à bande de la couche a donné une valeur du gap Eg de l’ordre de 4.05 eV.
The structural, optical and electrical properties of nanocrystalline ZnO: Al thin films
(Academic Press, 2014-04) Benhaoua, Boubaker; Rahal, Achour; Benramache, Said
The Al doped ZnO thin films were deposited by ultrasonic spray technique. The influence of Al doping on structural, optical and electrical properties of the ZnO thin films was studied. A set of Al doped ZnO (0–3.5 wt.%) were deposited at 350 °C. Nanocrystalline films with a hexagonal wurtzite structure with a strong (0 0 2) preferred orientation were observed after Al doping. The maximum value of grain size (33.28 nm) is attained with Al doped ZnO at 3 wt.%. Texture coefficient TC(h k l) of the four major peaks where evaluated. Optically, in visible region the transmissions spectra T(λ) show that the whole doped films exhibit lower values than the non doped one which has as transmittance more than 80%; whereas in the same region the optical transmissions of the doped films are affected by the doping ration. The band gap (Eg) increased after doping from 3.267 to 3.325 eV with increasing concentration of doping from 0 to 2.75 wt.%, respectively, according to the Burstein–Moss effect (blue shift of Eg) then beyond 3 wt.% in doping the band gap exhibit a slight decreasing due to the coexistence of Roth and Burstein–Moss effect. The electrical resistivity of the films decreased from 20 to 5.26 (Ω cm). The best results are achieved with 2.75 wt.% Al doped ZnO film.