Crystallization and phase separation mechanism of silicon oxide thin films fabricated via electron beam evaporation of silicon monoxide

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Tezin Türü: Yüksek Lisans

Tezin Yürütüldüğü Kurum: Orta Doğu Teknik Üniversitesi, Fen Bilimleri Enstitüsü, Fen Bilimleri Enstitüsü, Türkiye

Tezin Onay Tarihi: 2015

Öğrenci: DENİZ CİHAN GÜNDÜZ

Eş Danışman: RAŞİT TURAN, SELÇUK YERCİ

Özet:

Silicon nanocrystals (NCs) imbedded in a matrix of silicon oxide have drawn much attention due to their applications in optoelectronic devices and third-generation solar cells. Several methods were reported for the fabrication of Si NCs. Among these techniques, there are aerosol synthesis, chemical vapor deposition, ion implantation, magnetron sputtering and thermal evaporation. However, electron beam evaporation is a straightforward and effective technique for the fabrication of silicon oxide thin films since it allows a broad range control of evaporation rate. In most of the studies regarding electron beam enabled fabrication of silicon oxide thin films, co-evaporation of Si and SiO2 was employed. However, SiO is a less studied compound and the structure of commercially available SiO materials is still an issue of debate. Some studies characterized commercially available SiO materials as a mixture of Si and SiO2 rather than silicon (II) oxide. In this work, silicon oxide thin films were synthesized via e-beam evaporation of SiO. A broad range of annealing times and temperatures were spanned. Raman spectroscopy, XPS and FTIR were employed to study the mechanism of crystallization and phase separation of films. Raman spectroscopy results show that SiO cannot be considered as a composite mixture of Si and SiO2. Results indicate that phase separation and crystallization are two separate processes even at high temperatures. A minimum annealing temperature of between 800 and 9000 C is required to form Si NCs in this kind of a Si-O system. A complete crystallization of films was observed at 12000 C.