Effect of Annealing Temperature on the Physical Properties of the ZnO Thin Films Deposited by Ultrasonic Spray Pyrolysis

Abstract

In this work optical, electrical, structural and surface properties of polycrystalline ZnO thin films grown from aqueous solutions (with pH = 5) have been reported. The films have been deposited on glass substrates by ultrasonic spray pyrolysis technique at a substrate temperature of 350 ± 5 °C. Zinc acetate dissolved in deionized water has been used as starting solution. The ZnO thin films have been annealed in air at 450 and 500 °C to improve their physical characteristics. X-ray diffraction reveals that the films are polycrystalline in nature having zincite type crystal structure. Electrical resistivity values of the films have been increased after annealing process. Films are highly transparent in the visible region. The dependence of refractive index, n, and extinction coefficient, k, on the wavelength for ZnO films has been also reported. Optical band gap values have been determined using optical method. Finally, it has been concluded that annealing temperature has an important effect on the optical, structural, surface and electrical properties of the deposited films.

Keywords

• Thin film
• Annealing
• ZnO
• X-ray diffraction
• Surface properties

Ultrasonik Kimyasal Püskürtme Yöntemiyle Elde Edilen ZnO İnce Filmlerinin Fiziksel Özellikleri Üzerine Tavlama Sıcaklığının Etkisi

Abstract

Bu çalışmada, sulu çözeltilerden (pH = 5) elde edilen ZnO filmlerinin optik, elektriksel, yapısal ve yüzeysel özellikleri rapor edilmiştir. Filmler cam tabanlar üzerine 350 ± 5 °C taban sıcaklığında Ultrasonik Kimyasal Püskürtme tekniği ile çöktürülmüştür. Deiyonize su içerisinde çözünen Çinko asetat başlangıç püskürtme çözeltisi olarak kullanılmıştır. ZnO filmleri fiziksel özelliklerini iyileştirmek amacıyla 450 ve 500 °C sıcaklıklarda hava ortamında tavlama işlemine tabi tutulmuştur. X-ışını kırınımı analizleri, filmlerin polikristal formda ve zincite tipi kristal yapıya sahip olduğunu ortaya koymaktadır. Elektriksel özdirenç değerlerinin tavlama işlemi sonrasında arttığı belirlenmiştir. Filmler görünür bölgede yüksek geçirgenliğe sahiptirler. Ayrıca, filmler için kırılma indisi, n, ve sönüm katsayısının, k, dalgaboyuna bağlı değişimleri de rapor edilmiştir. Filmlerin optik bant aralığı değerleri optik metot yardımı ile belirlenmiştir. Sonuç olarak, tavlama sıcaklığının elde edilen filmlerin optik, yapısal, elektriksel ve yüzeysel özellikleri üzerinde önemli bir etkisi olduğu sonucuna varılmıştır.

Keywords

• İnce film
• Tavlama
• ZnO
• X-ışını kırınımı
• Yüzey özellikleri

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