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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
Effect of Substrate Temperature on Structural and Optical Properties of Cadmium Sulfide Thin Films Prepared by Evaporation Thermal Deposition

Authors: Nadheer Jassim Mohammed --- Hassan Abdullah Mahdi --- Safaa Farhood Madlul --- Adnan Kh. Hasan
Journal: Al-Mustansiriyah Journal of Science مجلة علوم المستنصرية ISSN: 1814635X Year: 2019 Volume: 30 Issue: 1 Pages: 205-209
Publisher: Al-Mustansyriah University الجامعة المستنصرية

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Abstract

In this research, we study the effect of substrate temperature (423K and 473K) on structural and optical properties for thin films of cadmium sulfide (CdS) by evaporation thermal dep-osition method on glass substrates and the thickness was about (390nm).XRD analysis showed that CdS thin films prepared at (423K and 473K) are single crystal and have pre-ferred orientation along (002). The grain size was found to be increased with increasing sub-strate temperature, in addition, the atomic force microscopy (AFM) an increase in root mean square (RMS) with an increase in substrate temperature. The absorbance and trans-mittance spectra have been recorded in the range off wave length(400-800nm), and it was found that the transmittance decreases with increasing substrate temperature, while the op-tical band gap decreases from (2.4-2.2ev) for allowed direct transition. CdS thin films should further investigated for application towards the fabrication of solar cells.

في هذا البحث ، قمنا بدراسة تأثير درجة حرارة الركيزة (423 و 473 كلفن) على الخواص التركيبية والبصرية للأغشية الرقيقة لكبريتيد الكادميوم (CdS) بواسطة طريقة الترسيب بالتبخير الحراري على ركائز الزجاج حيث كان سمك الغشاء حوالي 390 نانومتر . أظهر تحليل حيود الاشعة السينية XRD أن أغشية كبريتيد الكادميوم CdS الرقيقة التي تم إعدادها في درجة حرارة (423 و 473 كلفن) هي ذات بلورة منفردة ولها اتجاه مفضل على طول (002). وجد بان الحجم الحبيبي يزداد مع زيادة درجة حرارة الركيزة ، بالإضافة إلى ذلك ، فإن مجهر القوة الذرية (AFM) اضهر زيادة في معدل مربع الجذر التربيعي (RMS) عند زيادة درجة حرارة الركيزة. تم تسجيل اطياف الامتصاصية والنفاذية في مدى نطاق الموجة (400-800) نانومتر، وتبين أن النفاذية تقل مع زيادة درجة حرارة الركيزة ، في حين تنخفض فجوة الطاقة

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