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Optoelectronic and Thermal Propertie...

Mehmood, Naveed.

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Optoelectronic and Thermal Properties of Metallic Transition Metal Dichalcogenides = = Gecis Metal Dikalkojenitlerinin Optoelektronik ve Termal Ozellikleri.

紀錄類型:	書目-電子資源 : Monograph/item
正題名/作者:	Optoelectronic and Thermal Properties of Metallic Transition Metal Dichalcogenides =/
其他題名:	Gecis Metal Dikalkojenitlerinin Optoelektronik ve Termal Ozellikleri.
作者:	Mehmood, Naveed.
出版者:	Ann Arbor : ProQuest Dissertations & Theses, : 2020,
面頁冊數:	129 p.
附註:	Source: Dissertations Abstracts International, Volume: 83-10, Section: B.
Contained By:	Dissertations Abstracts International83-10B.
標題:	Photographs. -
電子資源:	https://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=29045061
ISBN:	9798209944829

Optoelectronic and Thermal Properties of Metallic Transition Metal Dichalcogenides = = Gecis Metal Dikalkojenitlerinin Optoelektronik ve Termal Ozellikleri.
Mehmood, Naveed.

Optoelectronic and Thermal Properties of Metallic Transition Metal Dichalcogenides =Gecis Metal Dikalkojenitlerinin Optoelektronik ve Termal Ozellikleri. - Ann Arbor : ProQuest Dissertations & Theses, 2020 - 129 p.

Source: Dissertations Abstracts International, Volume: 83-10, Section: B.

Thesis (Ph.D.)--Bilkent Universitesi (Turkey), 2020.

After the successful isolation of graphene monolayer from its bulky counterpart, there has been tremendous advancement in the field of 2D material. Transition metal dichalcogenides(TMDCs) is family of 2D materials comprising of a transition metal atom sandwiched between two chalcogen atoms. Photoresponse of semiconducting TMDCs has been studied extensively in literature. However, photoresponse from metallic TMDCs is unprecedented and hence has not been studied to explore which mechanism might prevail. Among our findings, we discovered that photocurrent generation through metallic TMDCs is possible and has a photo-thermal origin. Using scanning photo-current microscopy, we were able to obtain spatial photocurrent maps for both, zero biased and biased samples. At zero applied bias, the photocurrent generation is localized to metal-metal junction and governed by Seebeck effect. At finite applied bias, photocurrent from the whole crystal is observed and is due to photobolometric effect. As Photo-bolometric effect relies on photo-thermally induced resistance change of the material, we extended our study to extract thermal conductivity of metallic TMDCs via bolometric effect. As contact of crystal with substrate act as a heat sink, we used suspended crystals over a hole to thermally isolate it from any heat sink. Resistance change via laser induced heating is experimentally measured at the center of the suspended part of crystal. Measured resistance change is matched with expected resistance change which is calculated using thermal conductivity(κ) as a fitting parameter via commercially available finite element method package(COMSOL). This way, thermal conductivity of the metallic TMDCs is calculated with very high accuracy and precision.

ISBN: 9798209944829Subjects--Topical Terms:

627415
Photographs.

Optoelectronic and Thermal Properties of Metallic Transition Metal Dichalcogenides = = Gecis Metal Dikalkojenitlerinin Optoelektronik ve Termal Ozellikleri.
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520 $a After the successful isolation of graphene monolayer from its bulky counterpart, there has been tremendous advancement in the field of 2D material. Transition metal dichalcogenides(TMDCs) is family of 2D materials comprising of a transition metal atom sandwiched between two chalcogen atoms. Photoresponse of semiconducting TMDCs has been studied extensively in literature. However, photoresponse from metallic TMDCs is unprecedented and hence has not been studied to explore which mechanism might prevail. Among our findings, we discovered that photocurrent generation through metallic TMDCs is possible and has a photo-thermal origin. Using scanning photo-current microscopy, we were able to obtain spatial photocurrent maps for both, zero biased and biased samples. At zero applied bias, the photocurrent generation is localized to metal-metal junction and governed by Seebeck effect. At finite applied bias, photocurrent from the whole crystal is observed and is due to photobolometric effect. As Photo-bolometric effect relies on photo-thermally induced resistance change of the material, we extended our study to extract thermal conductivity of metallic TMDCs via bolometric effect. As contact of crystal with substrate act as a heat sink, we used suspended crystals over a hole to thermally isolate it from any heat sink. Resistance change via laser induced heating is experimentally measured at the center of the suspended part of crystal. Measured resistance change is matched with expected resistance change which is calculated using thermal conductivity(κ) as a fitting parameter via commercially available finite element method package(COMSOL). This way, thermal conductivity of the metallic TMDCs is calculated with very high accuracy and precision.
520 $a Tek katmanli grafenin bulk muadilinden ba¸sar ili bir ¸sekilde izolasyonunda sonra, iki boyutlu malzemeler alaninda b¨uy¨uk bir ilerleme oldu. Ge¸ci¸s metal kalkojenleri (GMK) bir ge¸ci¸s metal atomun iki kalkojen atomu arasina sikiltirilmasinii¸ceren iki boyutlu malzemelerin ailesidir. Yari iletken GMK'larin i¸si˘ga tepkileri literat¨urde kapsamli bir ¸sekilde incelendi. Ancak, metalik GMK'larin i¸si˘ga tepkilerine daha ¨onceden g¨or¨ulmedi ve dolayisiyla ge¸cerli olan i¸sleyi¸s ¸seklini ke¸sfedecek ¸cali¸smalar olmadi. Bulgularimiz arasinda, metalik GMK'lar aracili˘gi ile fotoakim ¨uretmenin m¨umk¨un oldu˘gunu ve bir foto-termal k¨okene sahip oldu˘gunu ke¸sfettik. Taramali foto-akim mikroskobunu numunelerin hem sifir ¨onakim hem de ¨on akimsiz kullanarak, uzamsal fotoakim haritalarini elde edebildik. Uygulanan sifir ¨onakiminda, foto akim ¨uretimi metal-metal ba˘glantisinda yer alir ve Seebeck etkisi ile y¨onetilir. Uygulanan ¨ol¸c¨ulebilir ¨on akimda, fotobolometrik etkiden dolayi, t¨um kristalden gelen foto akim g¨ozlemlendi. Foto-bolometrik etki malzemenin fototermal ind¨uklenen diren¸c de˘gi¸simine dayandi˘gindan, metallic GMK'larin termal iletimlerini bolometrik etki aracili˘gi ile elde etmek i¸cin ¸cali¸smamizi geni¸slettik. Kristalin alta¸s ile temasi, bir isi havuzu gibi davrandi˘gindan, herhangi bir isi havuzudan termal olarak izolasyon sa˘glamak i¸cin bir delik ¨uzerine birakilan kristalleri kullandik. Lazerin kaynaklandi˘gi isima ile olu¸san diren¸c de˘gi¸simi kristalin merkezinden deneysel olarak ¨ol¸c¨ulm¨u¸st¨ur. Piyasada satilan sonlu eleman metodu paketi ( COMSOL) aracili˘gi ile, Termal iletkenli˘gin (κ) uyma paramatresi olarak kullanildi˘gi ¨ol¸c¨um de˘gi¸simleri ve beklenen diren¸c de˘gi¸simi e¸sle¸smektedir. Bu ¸sekilde, metallik GMK'larin termal iletkenli˘gi y¨uksek kesinlik ve do˘gruluk ile hesaplandi.
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