پديد آورنده :
مدرسي، محمد حسين
عنوان :
بررسي اثر ناخالصي بر گاف الكتروني بلور اپتيكي CaS به روش DFT-1/2
مقطع تحصيلي :
كارشناسي ارشد
محل تحصيل :
اصفهان : دانشگاه صنعتي اصفهان
صفحه شمار :
ده، ۱۰۴ص.: مصور، جدول، نمودار
استاد راهنما :
جواد هاشمي فر
استاد مشاور :
هادي اكبرزاده
توصيفگر ها :
روش DFT-1/2 , محاسبات نظريه تابعي چگالي , نقصهاي نقطه اي , گاف انرژي , ترازهاي ناخالصي
استاد داور :
مجتبي اعلايي، اسماعيل عبدالحسيني سارسري
تاريخ ورود اطلاعات :
1397/11/06
تاريخ ويرايش اطلاعات :
1397/11/10
چكيده انگليسي :
AbstractComplete understanding of the role of intrinsic and extrinsic defects on the opticalproperties of functional semiconductors requires accurate hybrid experimental theoreticalanalysis In this respect ab initio calculation in the framework of density functional theoryhas been proven as a powerful and efficient theoretical tool In the Kohn Sham approach todensity functional theory while ground state propertiers are well described studyingexcited state properties of materials using common exchange correlation approximationshas always been a challenging topic Finding proper methods for excited state calculationsthat are both exact and fast is a major theoretical challenge In this study we employ thehalf occupation technique as an effective method with a computatioinal cost comparable tothat of common exchange correlation functionals to explore Ce and Sm doped CaS crystalswhich are luminous materials with many applications CaS is considered as an OSLmaterial in this study In the initial step the accuracy of half occupation technique wasexamined for calculating the band gap of some pure semiconductor materials withindifferent functionals and then the best functional was selected for calculations of thedoped samples Then the effects of Ce and Sm defects as well as vacancies on theelectronic structure and band gap of CaS host semiconductor were assessed by consideringseveral defect configurations The obtained results are compared with the availableexperimental absorption and radioactive luminescence RL spectra to identify the moreprobable configuration of the pure and doped samples It is argued that the obtainedelectronic structures are very helpful to understand the experimental observations ofoptical behaviour of the pure and doped CaS crystals keywords density functional calculations DFT 1 2 method point defects energy gap impurity energy levels
استاد راهنما :
جواد هاشمي فر
استاد مشاور :
هادي اكبرزاده
استاد داور :
مجتبي اعلايي، اسماعيل عبدالحسيني سارسري
