Synthesis and optoelectronic properties of two-dimensional transition metal dichalcogenides
Başlık çevirisi mevcut değil.
- Tez No: 403415
- Danışmanlar: Prof. SWASTIK KAR
- Tez Türü: Doktora
- Konular: Fizik ve Fizik Mühendisliği, Physics and Physics Engineering
- Anahtar Kelimeler: Belirtilmemiş.
- Yıl: 2017
- Dil: İngilizce
- Üniversite: Northeastern University
- Enstitü: Yurtdışı Enstitü
- Ana Bilim Dalı: Belirtilmemiş.
- Bilim Dalı: Belirtilmemiş.
- Sayfa Sayısı: 137
Özet
Özet yok.
Özet (Çeviri)
Graphene, the first 2D layered material, has had an enormous impact on the field of nanomaterials. It has been demonstrated that graphene has remarkable mechanical, electronic and optical properties such as high electrical conductivity, broad band absorption of light etc. However, graphene does not fulfill all the scientific requirements. Due to its zero-band gap, there are limited applications in optoelectronics. To overcome graphene's shortcoming, researchers have recently started to explore other 2-dimensional materials such as metal oxides, transition metal dichalcogenides, and hexagonal boron nitrides. Among the 2D materials, transition metal dichalcogenides (such as MoS2, MoSe2, WS2, WSe2) get more attention due to their tunable optical band gaps. It has been shown that these TMDs go from indirect to direct band gap as the layer count goes from bulk to monolayer, which is one of the requirements of optoelectronic device applications. Since these materials are layered, it can be mechanically exfoliated easily. However, large area and highly crystalline structures are required to observe optical and electronic properties, as well as to make these viable for commercial applications. In my research, I have developed a new synthesis method, called vapor phase chalcogenization, by using MoO2 or WO2 as a precursor unlike conventionally use Mo, W and MoO3, WO3 powders. With this method, we eliminated the chemical reaction process to one step with less oxygen content in the reaction. The quality of the grown samples is clearly observed by Raman, Photoluminescence, and Photocurrent Spectroscopy., and further analyzed by Transmission Electron Microscopy (TEM). For example, we have reported, for the first time, two distinctly new phonon processes in 2D MoS2 at 285 cm-1 and 487 cm-1. The ultra-high, optoelectronic-grade crystalline quality of MoS2 sample could be also observed through photocurrent spectroscopy, which clearly reveal excitonic states at room temperature. I further studied temperature dependent binding energies of excitons and quasiparticle band gap of MoS2. In my second work, I have extended my research to another 2D material, molybdenum diselinide (MoSe2), which is more favorable for solar cell applications due to its optical band gap range. We have observed detailed Raman processes of mono and few layer of MoSe2. which some of them are previously not explained experimentally and theoretically. I further studied excitation energy dependence of the MoSe2 Raman spectrum. Finally, creating artificially-stacked and in-plane 2D heterostructures has also opened a new research field for designing new materials. Building these materials also requires clean interfaces, and creating atomically-controlled van der waals (vdW) heterostructure is still challenging. We have synthesized rotationally aligned vertical MoS2-MoSe2 heterostrucutres to investigates the unexplored physical properties of these materials.
Benzer Tezler
- LiP-CVD growth of multi-shape monolayer WS2: Determination and investigation of defect domains
Çok şekilli tek katmanlı WS2' ün LiP-CVD ile büyütülmesi: Kusur alanlarının belirlenmesi ve incelenmesi
HASRET AĞIRCAN
Doktora
İngilizce
2024
Metalurji Mühendisliğiİstanbul Teknik ÜniversitesiMetalurji ve Malzeme Mühendisliği Ana Bilim Dalı
PROF. DR. GÜLDEM KARTAL ŞİRELİ
- Optoelektronik uygulamalara yönelik iki boyutlu metal halojenür ve geçiş metali dikalkojenit malzemelerin üretimi ve incelenmesi
Growth and investigation of two dimensional metal halide and transition metal dichalcogenide materials for optoelectronic applications
HABİP GÜNALP TAŞDELEN
Yüksek Lisans
Türkçe
2023
Bilim ve TeknolojiTOBB Ekonomi ve Teknoloji ÜniversitesiMikro ve Nanoteknoloji Ana Bilim Dalı
DR. ÖĞR. ÜYESİ AYDAN YELTİK
- Difenilmetilamin'den yeni ftalosiyanın vic-dioksim ve komplekslerinin sentezi
Synthesis of new phthalocyanine, vic-dioxime and complexes starting with diphenylmethylamtne
MEHASİN GÜNEŞ
- Püskürtmeli kurutma ve termal bozunma prosesleri ile ZnO esaslı partiküllerin ve kompozit yapıların sentezlenmesi ve karakterizasyonu
Characterization and synthesis of ZnO based particles and composite structures via spray drying and thermal decomposition processes
ŞEYMA DUMAN
Doktora
İngilizce
2016
Seramik Mühendisliğiİstanbul Teknik ÜniversitesiMalzeme Bilimi ve Mühendisliği Ana Bilim Dalı
DOÇ. DR. BURAK ÖZKAL
- Sentezlenen tek kristal Cu(II) kompleksinin yapı-özellik ilişkilerinin incelenmesi
Investigation of structure-property relations of synthesized single crystal Cu(II) complex
HATİCE ESRA CÖMERT
Yüksek Lisans
Türkçe
2024
Fizik ve Fizik MühendisliğiSakarya ÜniversitesiFizik Ana Bilim Dalı
PROF. DR. DAVUT AVCI