Determination of the Effect of Substrates on Electronic Defects in Silicon Thin Films

Abstract

The crystal volume ratios of silicon thin films vary depending on the substrate material and production conditions. The difference in crystal volume fraction also affects the types of electronic defects in the band gap of thin films. Electronic defects occur in silicon thin films due to atmospheric conditions or prolonged light exposure. Conductivity values changes can occur due to the change of electronic defects. In this study, silicon thin films were grown on three different substrates at the same time using the PECVD technique. The crystal volume ratios and surface morphology of the grown films were determined by Raman Spectroscopy and scanning electron microscopy (SEM) respectively. The grown silicon thin films intentionally were exposed to different atmospheric conditions (such as laboratory atmosphere, light soaking and UV aging) and electronic defects were created in the structure of the thin films. The behavior of these defects were investigated by electrical conductivity methods, which are time dependent dark conductivity, photoconductivity and mobility-lifetime calculations. As a result of the findings, it was determined that there were significant differences in the crystal volume ratios and thicknesses of the materials due to the different base materials, and that the materials were affected by different electronic defect states in the same atmospheric conditions due to these differences.

Keywords

• Silicon thin film
• PECVD
• Electronic defects
• Substrate effect

Silisyum İnce Filmlerde Taban Malzemelerin Elektronik Kusurlar Üzerine Etkisinin Belirlenmesi

Abstract

Silisyum ince filmlerin taban malzeme ve üretim koşullarına bağlı olarak kristal hacim oranları değişmektedir. Kristal hacim oranlarındaki bu farklılık ince filmlerin yasak enerji aralığında bulunun elektronik kusur çeşitlerini de etkilemektedir. Silisyum ince filmlerde atmosferik koşullardan ya da uzun süre ışığa maruz kalmalarından kaynaklı olarak elektronik kusurlar oluşmaktadır. Elektronik kusurların değişimine bağlı olarak iletkenlik değerlerinde değişimler oluşmaktadır. Bu çalışmada PECVD tekniği kullanılarak aynı anda üç farklı taban malzeme üzerine silisyum ince filmler büyütülmüştür. Büyütülen filmlerin kristal hacim oranları Raman Spektroskopisi ile yüzey morfolojileri ise taramalı elektron mikroskobu (SEM) yöntemi ile belirlenmiştir. Büyütülen silisyum ince filmler farklı atmosferik koşullara ( laboratuvar atmosferi, ışık banyosu ve UV ışık yaşlandırmasına) maruz bırakılarak bilinçli bir şekilde ince filmlerin yapısında elektronik kusurlar oluşturulmuştur. Bu kusurların davranışı elektriksel iletkenlik yöntemleri olan zamana bağlı karanlık iletkenlik, fotoiletkenlik ve mobilite-yaşam süresi hesaplamaları ile incelenmiştir. Elde edilen bulgular sonucunda taban malzemelerin farklı olmasından kaynaklı malzemelerin kristal hacim oranlarında ve kalınlıklarında belirgin farklılıklar oluştuğu ve bu farklılıklardan kaynaklı olarak malzemelerin aynı atmosferik koşullarda farklı elektronik kusur durumlarından etkilendikleri belirlenmiştir.

Keywords

• Silisyum ince film
• PECVD
• Elektronik kusurlar
• Taban malzeme etkisi

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