Sklopovi bazirani na slojevitim 2D materijalima i njihovim heterostrukturama

master's thesis

• Title (english): Transistors based on layered 2D materials and their heterostructures
• Author: Borna Radatović
• Mentor: Marko Kralj (mentor)
• Mentor: Damir Bosnar (mentor)
• Committee member: Hrvoje Buljan (predsjednik povjerenstva)
• Committee member: Marko Kralj (član povjerenstva)
• Committee member: Damir Pajić (član povjerenstva)
• Committee member: Damir Bosnar (član povjerenstva)
• Committee member: Vito Despoja (član povjerenstva)
• Granter: University of Zagreb; Faculty of Science; (Department of Physics); Zagreb
• Defense date and country: 2016-09-30, Croatia
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Physics

Abstract

Sagledavajući izazove napretka tehnologije izvjesno je da je silicijska tehnologija na zalasku svojih mogućnosti te da će u bliskoj budućnosti biti potrebno razviti nove materijale koji će svojim svojstvima kvalitetno odgovoriti na potrebe za daljnjim razvojem tehnologije. Riješenja mnogih izazova nudi grafen, koji predvodi čitavu klasu slojevitih 2D materijala. Unatoč nizu prednosti, zbog velike mane grafena u obliku nedostataka procjepa između vodljive i valentne vrpce, daljnja intenzivna istraživanja usmjerena su prema 2D materijalima koji u intrinzičnom obliku, ili u međusobnim kombinacijama slojeva posjeduju poluvodički procjep pogodan za tehnologiju u elektroničkim i sličnim uređajima. Jedni od prvih kandidata u tom smislu su MoS2 i WS2, koji su zbog dobivenih rezultata mobilnosti μ = 200cm2V -1s -1 i omjera struja paljenja/gašenja Ion / Ioff > 108 vrlo obećavajući. U ovome radu osmišljen je sistem izrade tranzistora na jednoslojnim strukturama MoS2 koristeći sjenaste maskirne folije obradene kratkim laserskim impulsima na mikro-skali. Takvim pristupom se izbjegava upotreba raznih polimera i kemikalija koji se u tradicionalnim poluvodičkim tehnologijama sustavno koriste za izradu tranzistora pomoću optičke ili elektronske litografije. U sklopu rada napravljena je aparatura koja omogućuje transportna mjerenja na mikro-skali, ali prva mjerenja do sada sintetiziranih struktura MoS2 ukazuju na pojave proboja naboja prije postizanja struje paljenja, zbog disipacije struje u sloj dielektrika koji je oslabio prilikom sinteze MoS2. U radu je korišten i skeniraju ći tuneliraju ći mikroskop sa 4 kontaktna vrška koji omogućuju mjerenja na nano-skali. Izmjerena je vodljivost gornjeg sloja sintetiziranih struktura MoS2 σ ≈ 10 -5 S/m2. Varirajući parametar međusobne udaljenosti vrškova pokazana je očekivana 2D vodljivost. Mjerenja na ovom uredaju dodatno su omogućila uočavanje pukotina u MoS2 slojevima na mikro-skali, koje su vjerojatno nastale uslijed brzog hlađenja uzoraka nakon sinteze.

Abstract (english)

Looking into the future advances of technology it’s obvious that silicium technology is at decay of its possibilities and that in near future it will be necessary to develop new materials that will adequately answer needs for future development of technology. One of the answers for those challenges can be found in graphene, which is leader of whole class of layered 2D materials. With whole set of advantages that it offers, one but major flaw in form of lack of bandgap between conducting and valent band, leads the direction of intense research towards 2D materials that have bandgap in theirs intrinsic or combined form, so they could be used in electronic devices. One of the first candidates in that sense are MoS2 and WS2, who are considered very promising because of first results of mobility μ = 200cm2V -1s -1 and on/off ratio Ion / Ioff > 108. In this master thesis we developed system for fabrication of transistors on single layered structures of MoS2 using stencil lithography. With that approach usage of different chemicals and polymers is avoided, which are common in traditional semiconductor technology for fabrication of transistors using optical and electronical lithography. In this thesis we constructed vacuum chamber that enables transport measurements on micro-scale, but first measurements done on synthesized structures of MoS2 indicate on dielectric breakdown before achieving on current, because of dissipation of electricity in dielectric layer that was weakened during synthesis of MoS2. We used STM with 4 tips that provides us with ability for measurements on nano-scale. We measured sheet conductivity of MoS2 σ ≈ 10 -5 S/m2 and varying parameter of tip distance we showed expected 2D conductivity. Additionally while using SEM we have spotted cracks in MoS2 layers, which are probably result of fast cooling after synthesis of MoS2 on samples.

• Keywords: slojeviti 2D materijali
• Keywords (english): layered 2D materials
• Language: croatian
• URN:NBN: urn:nbn:hr:217:297912
• Study programme: Title: Physics; specializations in: Research; Course: Research; Study programme type: university; Study level: integrated undergraduate and graduate; Academic / professional title: magistar/magistra fizike (magistar/magistra fizike)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2017-03-05 11:42:35