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Article
STRUCTURE AND OPTICAL PROPERTIES OF CdSe THIN FILMS AS A FUNCTION OF THE ANNEALING TIME

Author: Eman M. Noori
Journal: Al-Mustansiriyah Journal of Science مجلة علوم المستنصرية ISSN: 1814635X Year: 2016 Volume: 27 Issue: 5 Pages: 102-108
Publisher: Al-Mustansyriah University الجامعة المستنصرية

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Abstract

Cadmium (Cd) and selenide powder used to prepared cadmium selenide alloy. (CdSe) thin films of thickness 1320 Å were thermally evaporated technique deposited on glass substrate at room temperature. The as-deposited films were annealed in air atmosphere at 100oC, for three different annealing times (60, 120 and 180 minutes). The structural investigation performed by x-ray diffraction (XRD) technique; showed that the films have a polycrystalline and hexagonal (wurtzite) structure. For all deposited films the preferential orientation is (002).The value of lattice constant (a), grain size, strain and dislocation density of the deposited films are calculated and their variations with annealing times are studied. The absorbance spectra of cadmium selenide thin films were recorded in the wave length range of 400 nm to 900 nm. The values of the optical band gap energy, Eg (allowed direct transitions), calculated from the absorption spectra, ranged between (2.54 and 2.41) eV


Article
Annealing Temperature Dependent Structural, Optical and Electrical Properties of Thermally Deposited CdSe Thin Films

Author: Mohammad M. Ali
Journal: Journal of Basrah Researches (Sciences) مجلة ابحاث البصرة ( العلميات) ISSN: 18172695 Year: 2018 Volume: 44 Issue: 1A Pages: 33-46
Publisher: Basrah University جامعة البصرة

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Abstract

CdSe thin films have been deposited on suitably cleaned glass substrates by thermal evaporation method. The pressure during evaporation was maintained at 10-6 to 10-5 Torr. The samples are annealed in vacuum for 2h at various temperatures and characterized by structural, optical and electrical properties. The crystal structure and lattice parameter of these films were determined from X-ray diffractograms. It was observed that the films have a polycrystalline hexagonal (wurtzite) structure with preferred orientation along (002) plane. The crystallite size, dislocation density and micro strain were calculated by considering high intense diffraction peaks of the as-deposited and annealed films. It was found that the average size of the crystallites increases and the average dislocation density decreases with increasing annealing temperature. Absorption and transmittance spectra of these thin films were studied using UV-visible double beam spectrophotometer in the wavelength range of 300 – 1100 nm. The energy band gaps have been determined using absorption spectra. The values of the optical band gap energy, Eg, decreased from 2.37 – 2.08 eV with increasing the annealed temperature. Dependence of optical band gap on crystallite size has also been studied. The electrical resistivity and activation energy of CdSe thin films are calculated by two probe resistivity measurements. The decrease in dc resistivity with increase the grain size was also noted.


Article
The Effect of Cadmium Selenide Thin Film Thickness on Carbon Monoxide Gas Sensing Properties prepared by Plasma DC-Sputtering Technique

Author: Baha'a A. M. Al-Hilli
Journal: Iraqi Journal of Science المجلة العراقية للعلوم ISSN: 00672904/23121637 Year: 2018 Volume: 59 Issue: 4C Pages: 2234-2241
Publisher: Baghdad University جامعة بغداد

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Abstract

Cadmium Selenide (CdSe) thin films have been deposited on a glass substrate utilizing the plasma DC-sputtering method at room temperature at different deposition time in order to achieve different films thickness, and studied its sensitivity to the carbon monoxide CO gas which are show high response as the film thickness increases, the DC-conductivity and photoconductivity are also studied and which are increased too as the film thickness increases, that indicates the good semiconducting behavior at room temperature and light environments.


Article
Study The Effect of Thickness on The Structural and Optical constant of CdSe Thin Films
دراسة تاثير السمك على الخواص التركيبية والثوابت البصرية لاغشية سيلينايد الكادميوم (CdSe)الرقيقة

Authors: T.H.Mahmoud طاهر حمد محمود --- B.K.Hassun بشرى كاظم حسون --- S.A.Make سمير عطا مكي
Journal: Journal of College of Education مجلة كلية التربية ISSN: 18120380 Year: 2017 Issue: 1 Pages: 249-264
Publisher: Al-Mustansyriah University الجامعة المستنصرية

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Abstract

In this research , pure (CdSe) thin films with a different thickness ( 300 , 500 ,700 ,900) ± 20 nm was deposited on glass substrate in room temperature ( 300K ) with deposition rate (0.7±0.01) nm /sec by thermal evaporation under vacuum technique , and then studies their structure and optical properties .The resultant of the structural analysis showed that all films with all thickness prepared were polycrystalline in nature and have hexagonal type structure with atomic growth in three crystal orientation which it [002] , [102] and [103] with Preferred orientation along [002] plane for all Prepared films.The optical analysis measurement showed that all prepared films have absorption coefficient with a value larger than (∝ > 〖10〗^4 〖cm〗^(-1)) and this value was increased when increasing the film thickness especially in the visible range of electromagnetic spectrum , the optical energy gap was founded in the range ( 1.70 -1.72 ) eV.

تم في هذا البحث ترسيب اغشية سيلينايد الكادميوم النقية بطريقـــة التبخير الحراري فــي الفراغ عـلى قواعد من الزجاج بــدرجة حـرارة الغرفــــــة ( 300k) وبسمــك مـختلف 20 nm±) 900 ،700 ، 500 ، 300 ) وبـمعـدل تــرسيب sec / 0.7nm ووجد بـان الاغشيـة النـاتجة كـانت ذات جـودة عالية مــن حيــث تجانس الغشاء والتصاقيته بالارضيات الزجاجية، ودرسـت خواصها التركيبية والبصرية. اظهرت نتائـج الفحوصــات التركيبية بـان جميع الاغشيــة الرقيقة ,والمحضرة بسمك مختلف كانت متعددة التبلور ومـن النـوع السداسـي مع نمو ذري بثلاثة اتجاهات بلورية هـي [103] و[102] و[002] كان المميز والسائد منها في الاتجاه [002] وللنماذج المحضرة كافة .امـــا نتائج الفحوصات البصريــة فـقـد بــيـنت بـان مـعامـل الامتصـاص للاغـشية المحــضرة كـــان ذو قــيمة اكــبر من (〖cm〗^(-1) α >〖10〗^4 ) وان هـذه الـقيمة تـزداد بشكل عام بزيادة السمك لاسيما عند الطاقات الفوتونية الواطئة ، اما بالنسبة الى قيمة فجوة الطاقة البصرية فلقد كانت ضمن المدى eV(1.70-1.72) .


Article
The Effect of the (Se) percentage on Compositional, Morphological and structural properties of Bi2(Te1-xSex)3 thin films
تأثير نسبة (Se) على الخواص السطحية والتركيبية لاغشية Bi2(Te1-x Sex)3 الرقيقة

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Abstract

Alloys of Bi2[Te1-x Sex]3 were prepared by melting technique with different values of Se percentage (x=0,0.1,0.3,0.5,0.7,0.9 and 1). Thin films of these alloys were prepared by using thermal evaporation technique under vacuum of 10-5 Torr on glass substrates, deposited at room temperature with a deposition rate (12nm/min) and a constant thickness (450±30 nm).The concentrations of the initial elements Bi, Te and Se in the Bi2 [Te1-x Sex]3 alloys with different values of Se percentage (x), were determined by XRF,The morphological and structural properties were determined by AFM and XRD techniques. AFM images of Bi2[Te1-x Sex]3 thin films show that the average diameter and the average surface roughness increase with the increase of the percentage of Se. The X–ray diffraction measurements for bulk and thin films of Bi2[Te1-xSex]3 have polycrystalline structure with rohmbohedral structure, with space group R3m, and a strong (015) preferred orientation, the crystallite increase with the increase of Se percentage .

تم تحضير سبائك المركب Bi2(Te1-x Sex)3 بعملية صهر المواد الاولية وفق نسب مختلفة لنسبة السيلينيوم (x=0 , 0.1 ,0.3 ,0.5 ,0.7,0.9 and 1). الاغشية الرقيقة لهذا المركب تم تحضيرها باستخدام تقنية التبخير الحراري تحت ضغط فراغ يصل الى 10-5 torr)) حيث تم ترسيب المادة على قواعد زجاجية نظيفة في درجة حرارة الغرفة بمعدل ترسيب((12nm/min بسمك ((450±30 nm. . قد تم التأكد من نسب المواد الأولية (Bi ,Te and Se) باستخدام جهاز فلورة الاشعة السينينة XRF , اما الخواص التركيبية للسبائك والاغشية الرقيقة لمركب Bi2(Te1-x Sex)3 باختلاف نسبة السيلينوم فيها بواسطة جهاز حيود الاشعة السينية XRD اما الخواص السطحية للاغشية الرقيقة تم فحصها باستعمال جهاز AFM وقد وجد ان اقطار الحبيبات تزداد بزيادة نسبة السيلينيوم فيها وكذلك يزداد معدل الخشونة فيها ان قياس حيود الاشعة السينية وجد ان السبائك والاغشية الرقيقة لها تركيب متعدد التبلور ذو تركيب سداسي وفسحة مجموعة R3m وكانت القمة السائدة والاقوى هي (015) وكذلك بينت ان حجم البلوريات يزداد بزيادة نسبة السيلينيوم في المركب .

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