Publication: Manyetik Yapıiletkenlerin Hazırlanması ve Karakterizasyonu
Abstract
Bu çalışmada Ferromanyetik yarıiletken AB2X4 (A=Cd, Cu; B=Cr; X=S, Se) tipi üçlü filmler ve nano-parçacıklar Kimyasal Banyo Büyütme (CBD) ve Kimyasal İndirgeme metotları kullanılarak laboratuarımızda hazırlandı. Filmler farklı alt-taşlar, farklı konsantrasyonlar ve farklı büyütme sürelerine göre hazırlandı. Hazırlanan filmlerin optik, manyetik, yapısal ve morfolojik özellikleri UV-visible spektrometre, ESR, XRD, SEM ve EDAX teknikleri kullanılarak belirlendi. Kimyasal İndirgeme metoduyla hazırladığımız nano-partiküllerin boyutları deney koşullarına bağlı olarak oluşturuldu, yaklaşık 50- 200 nm mertebesinde oldukça homojen ve düzgün bir dağılım gözlemlendi. Alt-taşlar üzerine büyütülen filmlerin oldukça düzgün ve homojen bir yapıya sahip oldukları ve poli-kristal filmler oldukları görüldü. SEM görüntüsünden film yüzeylerinde herhangi bir yapısal bozukluklar ve düzensizliklerin olmadığı gözlendi. Bu çalışmanın temel amacı istenen kalitedeki ferromanyetik yarıiletken nano-parçacıkların elde edilmesi için gerekli deneysel koşulları belirlemekti ve bu koşullar deneysel çalışmalarımızla başarılı bir şekilde belirlendi. Optik özellikleri UV-Vis spektrometreyle 300–800 nm arasında ölçülerek yarıiletken band genişliği belirlendi. Yapılan analizler sonucu optik soğurma çizgisinin CdCr2S4 ve CuCr2S4 için sırasıyla, 2.43 eV ve 2.45 eV olduğu bulundu. Bu örnekler için Curie sıcaklıkları ölçüldü ve sırasıyla 85K ve 380K civarında olduğu bulundu. CuCr2S4 filminde Coercive alanın, azalan sıcaklığın bir fonksiyonu olarak arttığı bulundu. Ayrıca, bu örnekte bazı manyetik anomalik davranışlar gözlendi.
PREPARATİON AND CHARACTERİZATION OF MAGNETİC SEMİCONDUCTORS It this study ferromagnetic semiconducting films of the type AB2X4 (A=Cd, Cu; B=Cr; X=S, Se) were fabricated in our laboratory using Chemical Bath Deposition (CBD) and Chemical Reduction methods. Films are produced with different substrates, different concentrations and different growing time intervals. Fabricated films are then analyzed to determine their optical, magnetic, structural and morphologic properties using UV –vis spectrometric, ESR, XRD, SEM and EDAX techniques. The dimensions of nano-particles produced by the chemical reduction method, depending on the experimental conditions, showed quite homogenous distribution with approximately 50-200 nm in average diameters. The ploy-crystal films grown on substrates showed remarkably homogenous structure with clean smooth surfaces. There were no structural defects or pinholes observed on the surfaces under SEM. One of the main objective of this study was to determine the experimental conditions for efficient production of ferromagnetic semiconducting nano-particles with desired qualities and we successfully underlined these conditions in our experimental studies. The optical properties were measured using UV-vis spectrometer with wave length in the range of 300-800 nm and the band gap determined. The optical absorption lines for CdCr2S4 and CuCr2S4 were found to be at 2.43 eV and 2.45 eV respectively. The curie temperatures were also measured by for these samples and were found to be at about 85K and 380 K respectively. The coercive field in CuCr2S4 sample found to increase as a function of decreasing temperature. In addition some magnetic anomalies were also observed in this sample.
PREPARATİON AND CHARACTERİZATION OF MAGNETİC SEMİCONDUCTORS It this study ferromagnetic semiconducting films of the type AB2X4 (A=Cd, Cu; B=Cr; X=S, Se) were fabricated in our laboratory using Chemical Bath Deposition (CBD) and Chemical Reduction methods. Films are produced with different substrates, different concentrations and different growing time intervals. Fabricated films are then analyzed to determine their optical, magnetic, structural and morphologic properties using UV –vis spectrometric, ESR, XRD, SEM and EDAX techniques. The dimensions of nano-particles produced by the chemical reduction method, depending on the experimental conditions, showed quite homogenous distribution with approximately 50-200 nm in average diameters. The ploy-crystal films grown on substrates showed remarkably homogenous structure with clean smooth surfaces. There were no structural defects or pinholes observed on the surfaces under SEM. One of the main objective of this study was to determine the experimental conditions for efficient production of ferromagnetic semiconducting nano-particles with desired qualities and we successfully underlined these conditions in our experimental studies. The optical properties were measured using UV-vis spectrometer with wave length in the range of 300-800 nm and the band gap determined. The optical absorption lines for CdCr2S4 and CuCr2S4 were found to be at 2.43 eV and 2.45 eV respectively. The curie temperatures were also measured by for these samples and were found to be at about 85K and 380 K respectively. The coercive field in CuCr2S4 sample found to increase as a function of decreasing temperature. In addition some magnetic anomalies were also observed in this sample.