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Register a new userAnalytical and Experimental Study of Structural and optical properties of ther
دراسة تحليلية و تجريبية للخصائص الضوئية و البنيوية للأغشية الرقيقة CdTe المرسبة بالتبخير الحراري
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رسبتْ أغشية رقيقة من الكادميوم تيلورايد (CdTe) على ركازات من الزجـاج بثخانـات مختلفـة بطريقة التبخير الفيزيائي الحراري (evaporation thermal). الثخانات الهندسـية للأغـشية جـرى حسابها من طيف الانعكاس للأغشية، و درست الخواص البنيوية و التوجه البلوري لهذه الأغشية بتحليـل انعراج الأشعة السينية (XRD) و حددت وسطاء البنية مثل ثابت الشبيكة البلورية (a) و كثافة الانخلاعات (δ) و عامل الإجهاد (ε), و أبعاد الحبيبات (D), و لوحظ ازدياد الأبعاد الحبيبيـة و نقـصان فـي الإجهـاد المكروي و كثافة الإنخلاعات بازدياد ثخانة الغشاء المرسب. و تبين أن الأغشية ذات بنية مكعبة مركزيـة الوجوه، و حدد التوجه البلوري المفضل للغشاء و الحبيبات المتشكلة عليه فكـان الوجـه (111) موازيـاً لسطح الركازة. كما استخدمنا مقياس الطيف في الدراسة الضوئية، و لاحظنا تزايداً في عامل الامتـصاص بزيادة ثخانة الغشاء و تناقصاً في عرض فجوة الطاقة بازدياد الثخانة.
CdTe Thin films were deposited on glass substrates by thermal evaporation method. The geometric thickness was calculated using interferometric method based on reflectance curve recorded with the spectrophotometer. The XRD analysis and optical characterizations of CdTe films with different optical thicknesses reveals that the structure of the films is polycrystalline with preferential orientation (111). The structure constant (a), crystallite size (D), dislocation density (δ) and strain (ε) were calculated, and it is observed that the crystallite size increases but micro-strain and dislocation density decreases with increases in thin film thickness. The overall absorbance has been increased with the film thickness and the direct band gap was obtained. It decreases with the increase in the thickness of the films.
References used
Cheng, J., Fan, D. Wang, H., Liu. B. W. (2003). Semicond. Sci. Technol. 18, 676
Shaaban, E. R., Afify, N., El-Taher. (2009). Effect of film thickness on microstructure parameter and optical constants of CdTe thin films Journal of Alloys and Compounds 482 , 400-404
Laitha, S., Karazhanov, S. Zh., Ravindran, P., Senthilarasu S. and all…., (2007). Electronic structure, structural and optical properties of thermally evaporated CdTe thin films. Physica B 38, 227-238
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CdTe Thin films were deposited on silicon substrates by thermal
evaporation method. The geometric thickness was calculated using
interferometric method based on reflectance curve recorded with the
spectrophotometer. The Reflection of High-Energy E
lectron Diffraction
(RHEED) patterns and XRD analysis reveals that the structure of the films are
polycrystalline with preferential orientation (111). The structure constant (a),
crystallite size (D), dislocation density (δ) and strain (ε) were calculated, and it
is observed that the crystallite size increases but micro-strain and dislocation
density decreases with increases in thin film thickness. The composition of the
samples was determined by Energy Dispersive X-ray Analysis (EDX) and it is
found that the wt.% of Cd increases and the wt.% of Te decreases with the
increases of film thickness due to the re-evaporation of Te.
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Slabs are considered one of the most exposed elements to disasters and deformities
that can be clear to the viewer. These deformities are reflected as sign of defects that
appear clearly on big slabs. So, here comes the importance of applying and d
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