Optimizacija parametara optičke litografije za transportnu karakterizaciju odabranih van der Waalsovih materijala

master's thesis

• Title (english): Optimization of optical lithography parameters for transport characterization of selected van der Waals materials
• Author: Filip Šurina
• Mentor: Mario Novak (mentor)
• Committee member: Mario Novak (predsjednik povjerenstva)
• Committee member: Emil Tafra (član povjerenstva)
• Committee member: Zoran Rukelj (član povjerenstva)
• Committee member: Ivan Kupčić (član povjerenstva)
• Committee member: Damir Pajić (član povjerenstva)
• Granter: University of Zagreb; Faculty of Science; (Department of Physics); Zagreb
• Defense date and country: 2024-09-27, Croatia
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Physics

Abstract

U ovom radu Bi2Sr2CaCu2O8+x (bizmut stroncij kalcij bakrov oksid) kristali su sintetizirani i optimalno dopirani kisikom na 550ºC tijekom 24 sata. Zbog svoje kvazidvodimenzionalne strukture, kristale je lako raslojiti (eksfolirati) na tanke listiće. Istražene su dvije metode mehaničke eksfolijacije, koristeći 3M Scotch ljepljivu traku i ljepljivu traku osjetljivu na UV svjetlost. Scotch traka je proizvela više listića, ali je ostavljala ljepilo na silicijskoj podlozi na koju se vršila eksfolijacija. Dvije metode eksfolijacije uz pomoć su isprobane: toplinski i zlatom potpomognuta eksfolijacija, pri čemu je zlatom potpomognuta eksfolijacija dala najveći broj tankih listića. Nakon optimizacije parametara optičke litografije, izrađeni su zlatni kontakti s najtanjim značajkama širine 40 μm, ali polaganje uzoraka na kontakte nije bilo uspješno. Druga metoda kontaktiranja uključivala je lemljenje indijem, pri čemu je dobiven kontkatirani uzorak s otporom od (392 ± 2) kΩ. AFM mjerenja pokazala su da su eksfolirani monoslojni listići debljine 3-4 nm. Mjerenja transportnih svojstava makroskopskih (bulk) uzoraka Bi-2212 pokazala su linearan pad otpora do Tc = 90.8 K bez magnetskog polja.

Abstract (english)

In this study, Bi2Sr2CaCu2O8+x (bismuth strontium calcium copper oxide) crystals were synthesized and optimally doped with oxygen at 550 ºC for 24 hours. Due to their quasi-two-dimensional structure, the crystals are easily exfoliated into thin flakes. Two methods of mechanical exfoliation were investigated, using 3M Scotch tape and UV-sensitive adhesive tape. The Scotch tape produced more flakes, but left adhesive residue on the silicon substrate used for exfoliation. Two assisted exfoliation methods were tested, thermal and gold-assisted exfoliation, with the gold-assisted exfoliation producing the largest number of thin flakes. After optimizing the optical lithography parameters, gold contacts with the thinnest features measuring 40 μm were fabricated, but the placement of the samples onto the contacts was unsuccessful. The second contact method involved soldering with indium, resulting in a contacted sample with a resistance of (392 ± 2) kΩ. AFM measurements showed that the exfoliated monolayer flakes were 3-4 nm thick. Transport measurements of macroscopic (bulk) Bi-2212 samples showed a linear decrease in resistance up to Tc = 90.8 K without a magnetic field.

• Keywords: optička litografija
• Language: croatian
• URN:NBN: urn:nbn:hr:217:711354
• Study programme: Title: The University Integrated Undergraduate and Graduate Programme in Physics; Research Physics; specializations in: Research Physics; Course: Research Physics; Study programme type: university; Study level: integrated undergraduate and graduate; Academic / professional title: sveučilišni magistar fizike (sveučilišni magistar fizike)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2025-01-31 13:03:58