RF saçtırma ile üretilen SnS ince filmlerine SnCl2 ısıl işleminin etkisi

Bu çalışmada SnCl2 işleminin SnS ince filmlerine etkisi araştırıldı. SnS ince filmleri, RF saçtırma ile büyütülürken, SnCl2 işlemi ıslak kimyasal yöntem ile uygulandı. SnCl2 ısıl işlemi uygulanan ve tavlanan olarak gruplandırılan örnekler, hava atmosferinde ısıl işlemine tabi tutulurken, tavlanmayan örneğe herhangi bir ısıl işlem uygulanmadı. Hiçbir işlem uygulanmayan örnek, ortorombik SnS fazında büyüdü. SnS örneğinin hava ortamında tavlanması, ortorombik SnS'nin yanı sıra baskın olmayan SnS2 ve SnO2 fazlarının oluşumuna neden oldu. SnS'ye SnCl2 ısıl işlemi uygulanmasının kristallenmeyi kötüleştirdiği ve özellikle SnO2 oksit fazının daha baskın hale getirdiği görüldü. Raman spektrumları, numunelerde SnS ve SnS2 fazlarının varlığını doğruladı, ancak SnO2 fazına dair bir bulguya rastlanmadı. SEM görüntüleri, işlem uygulanmayan ve tavlanan örneklerde bıçağa benzeyen, yoğun tane oluşumu sergiledi. Bununla birlikte, SnCl2 ısıl işlemi, numunenin yüzey morfolojisini tamamen değiştirerek, derin kırıklarla bölünen birkaç bölgeden oluşan bir yapıya neden oldu. EDS, işlem uygulanmayan ve tavlanan numunelerin belirgin bir Sn zengini kompozisyonunu ortaya çıkardı (Sn/S~1.2). SnCl2 ısıl işlemi ise SnS’nin atomik dağılımında büyük bir kükürt kaybına neden olarak Sn/S oranının 7.5 civarına yükselmesine yol açtı. İşlem görmeyen ve tavlanan örneklerin bant aralıkları, sırasıyla 1.43 eV ve 1,45 olarak hesaplandı. Bununla birlikte, SnCl2 ısıl işlemi, bant aralığının 1.56 eV'ye yükselmesine neden oldu. Analiz sonuçları, ıslak kimyasal yöntem ile SnCl2 ısıl işlemi uygulanmasının SnS ince filmlerin özelliklerinde ciddi bir değişime neden olduğunu göstermektedir. Bu bağlamda, SnCl2 ısıl işleminin optimizasyon süreçleriyle daha da geliştirilebileceği söylenebilir.

Anahtar Kelimeler:

SnS, SnCl2 işlemi, RF saçtırma, havada tavlama

Effect of SnCl2 heat treatment on SnS thin films deposited by RF sputtering

In this study, the effect of SnCl2 treatment on SnS thin films was investigated. SnS thin films were grown by RF sputtering and SnCl2 treatment was applied by wet chemical processing. While the samples grouped as SnCl2 heat treated and annealed were subjected to annealing in air atm, the as-deposited sample was not applied any annealing process. The as-deposited sample grew in the orthorhombic SnS phase. Annealing of the SnS sample in air environment led to the formation of orthorhombic SnS as well as non-dominant SnS2 and SnO2 phases. It was found that applying SnCl2 heat treatment to SnS deteriorated the crystallization and especially the SnO2 oxide phase became more dominant. Raman spectra confirmed the presence of SnS and SnS2 phases in the samples, but no evidence of SnO2 phase was found. SEM images showed bladelike, dense grain formation in the as-deposited and annealed samples. However, SnCl2 heat treatment completely changed the surface morphology of the sample, causing it to transform into a structure consisting of several domains split by deep fractures. EDS revealed a distinct Sn-rich composition of the as-deposited and annealed samples (Sn/S~1.2). On the other hand, SnCl2 heat treatment caused a massive loss of sulphur in the atomic distribution of the SnS and it was seen that the Sn/S ratio increased to around 7.5. The band gaps of the as-deposited and annelaed samples were calculated as 1.43 eV and 1.45, respectively. However, SnCl2 heat treatment led to an increase to 1.56 eV of the band gap. Analysis results show that SnCl2 treatment by the wet processing causes a significant change on the characteristics of SnS thin film. In this context, it can be said that SnCl2 heat treatment can be further improved with optimization processes.

Keywords:

SnS, SnCl2 treatment, RF sputtering, air annealing,

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