Yarıiletken IV-VI tabakalı bileşiklerden SNS ve SNSE'de optik band kenarı ölçümleri
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1997-05-30
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Selçuk Üniversitesi Fen Bilimleri Enstitüsü
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info:eu-repo/semantics/openAccess
Abstract
Bu çalışma tabakalı bileşiklerden olan SnS ve SnSe yarıiletken malzemelerinde, özellikle temel band kenarı civarında optik özelliklerin nasıl değiştiğinin araştırılması amacıyla yapılmıştır. Bu amaçla, tek kristal SnS ve SnSe yarıiletken malzemeleri üzerinde, yakın morötesi, görünür ve yakın kırmızıötesi spektral bölgeyi kapsayan soğurma ve yansıma ölçümleri gerçekleştirilmiştir. Soğurma spektrumları ilk olarak standard yöntemlerle analiz edilmiş ve direkt ve indirekt geçiş enerjileri belirlenmeye çalışılmıştır. Daha sonra, özellikle indirekt geçiş enerjilerinin tayininde sıkça kullanılan diferansiyel yöntemi yardımı ile numunelerin indirekt geçiş enerjileri ve geçişe katılan fonon enerjileri belirlenmiştir. Yansıma ölçüm sonuçlan ise, özellikle bulk numunelerin yansıma spektrumlarının değerlendirilmesinde yaygın biçimde kullanılan Kramers-Kronig yöntemi yardımı ile analiz edilmiş, bu amaçla elde edilen yansıma verileri bir bilgisayar programı yardımı ile sayısal integrasyona tabi tutularak sonuçta numunelere ait birçok temel optik parametre, kırılma indisi, dielektrik sabiti v.b. belirlenmiştir. Bunlara ek olarak, Kramers-Kronig dönüşümü sonucu bulunan kırılma indisi verileri üzerinde Wemple diDomenico dispersiyon analizi gerçekleştirilmiş ve numunelere ait dispersiyon parametreleri tayin edilmiştir. Elde edilen sonuçlar, her iki numune için de bulunan kırılma indisi ve ilgili diğer optik sabitlerin, kutuplanmış ışık ile bulunan sonuçlara genelde yakın olduğunu ortaya koymuştur. Belirlenen geçiş enerji değerleri farklı kutuplanma durumları ile elde edilen değerlere yakın veya bunların bir ortalaması şeklindedir. Wemple diDomenico dispersiyon analizi sonucu bulunan dispersiyon parametreleri ise genelde daha küçük çıkmıştır ki bu, kutuplanmamış ışık kullanıldığından beklenilen bir durumdur.
This study was performed to determine how optical properties of layered semiconducting compounds, SnS and SnSe, change at the fundamental band edge. For this purpose, on the single SnS and SnSe semiconducing materials, absorption and reflection measurements including near ultraviolet, visible and near infrared spectral regions were made. Firstly, absorption spectra were analyzed by means of standard methods and it was attempted to determine the direct and indirect transition energies. After this, by means of the differential method which has been frequently employed especially in determining of indirect transition energies, the indirect energies and fonon energies corresponding to these transitions were determined. Reflection data were studied by Kramers-Kronig transformation method which has been used quite widely in analysis of reflectance spectra of bulk materials. For this purpose, a computer programme was constructed to integrate numerically the reflection data and thus many basic optical parameters of these materials, e.g. refractive index, dielectric constant, were computed. In addition, by using the refractive index results determined by Kramers-Kronig transformation, Wemple diDomenico dispersion analysis was performed and related dispersion parameters were obtained. The results obtained for both materials were shown that, refractive index and other related optical constants were generally near at the values of those obtained by using polarized light in other studies. Also, the transition energies determined in this study were either near any polarized value or might be assumed as an average of two different ploarized values. The dispersion parameters that is obtained by Wemple diDomenico dispersion analysis were found smaller than the polarized values. This situation is expected because polarized light interacts with the materials more strongly than unpolarized light does.
This study was performed to determine how optical properties of layered semiconducting compounds, SnS and SnSe, change at the fundamental band edge. For this purpose, on the single SnS and SnSe semiconducing materials, absorption and reflection measurements including near ultraviolet, visible and near infrared spectral regions were made. Firstly, absorption spectra were analyzed by means of standard methods and it was attempted to determine the direct and indirect transition energies. After this, by means of the differential method which has been frequently employed especially in determining of indirect transition energies, the indirect energies and fonon energies corresponding to these transitions were determined. Reflection data were studied by Kramers-Kronig transformation method which has been used quite widely in analysis of reflectance spectra of bulk materials. For this purpose, a computer programme was constructed to integrate numerically the reflection data and thus many basic optical parameters of these materials, e.g. refractive index, dielectric constant, were computed. In addition, by using the refractive index results determined by Kramers-Kronig transformation, Wemple diDomenico dispersion analysis was performed and related dispersion parameters were obtained. The results obtained for both materials were shown that, refractive index and other related optical constants were generally near at the values of those obtained by using polarized light in other studies. Also, the transition energies determined in this study were either near any polarized value or might be assumed as an average of two different ploarized values. The dispersion parameters that is obtained by Wemple diDomenico dispersion analysis were found smaller than the polarized values. This situation is expected because polarized light interacts with the materials more strongly than unpolarized light does.
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Yarı iletkenler, Semiconductors, Optik özellikler, Optical properties, Tabakalı maddeler, Layered materials
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Şafak, H. (1997). Yarıiletken IV-VI tabakalı bileşiklerden SNS ve SNSE'de optik band kenarı ölçümleri. Selçuk Üniversitesi, Yayımlanmış doktora tezi, Konya.
