Utjecaj prostornog ograničenja fonona na fotoluminescenciju nanostrukturiranog silicija

master's thesis

• Title (english): Influence of phonon confinement on to photoluminescence of porous silicon
• Author: Vlatko Gašparić
• Mentor: Mile Ivanda (mentor)
• Mentor: Mihael Grbić (mentor)
• Committee member: Mihael Grbić (predsjednik povjerenstva)
• Committee member: Mile Ivanda (član povjerenstva)
• Committee member: Ivo Batistić (član povjerenstva)
• Committee member: Hrvoje Buljan (član povjerenstva)
• Committee member: Emil Tafra (član povjerenstva)
• Granter: University of Zagreb; Faculty of Science; (Department of Physics); Zagreb
• Defense date and country: 2017-07-12, Croatia
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Physics

Abstract

Predstavljen je razlog i motivacija proučavanja luminiscencije poroznog silicija: daljnji napredak u mikroelektroničkoj industriji i integracija s optičkim komponentama. Uveden je model kvantnog zatočenja ekscitona u nanokristalićima unutar sloja poroznog silicija kao jedan od glavnih uzroka luminiscencije te su navedeni i ostali uzroci. Uveden je i raspisan model fononskog zatočenja te veza s Ramanovom spektroskopijom kao glavnom karakterizacijskom tehnikom poroznog silicija u radu. U Materijalima i metodama izložena je elektrokemija poroznog silicija i reprezentativna IV karakteristika procesa jetkanja. Predstavljena je komorica za jetkanje poroznog silicija napravljena u okviru rada, a detaljno je opisana u Dodatku. Proučena je tehnika određivanja i zadavanja sastava elektrolita za jetkanje, čiji je izvod raspisan u Dodatku. Opisana je procedura mjerenja otpornosti silicijeve pločice, pripreme uzoraka, mjerenja IV karakteristika i jetkanja uzoraka. Predstavljena je teorija Ramanove spektroskopije i tehnika proučavanja fononskog zatočenja. Pokazano je da otpornost na jednoj pločici i između pločica varira zanemarivo da bi utjecala na dobivene jetkane uzorke. Proučavane su IV karakteristike procesa jetkanja u potrazi za idealnim parametrima jetkanja, no za visoke koncentracije fluorovodične kiseline nije bilo moguće uočiti režime. Analizirane su tri serije uzoraka gdje se prilagodbom modela fononskog zatočenja na Ramanov spektar dobila procjena veličine kristalića. Snimljena fotoluminiscencija je uspoređena s veličinom kristalića i pozicijom fononske vrpce. Dobiveno je da intenzitet fotoluminiscencije raste smanjivanjem kristalića, a između energije fotoluminiscencije i veličine kristalića nije dobivena povezanost. Rezultati su usporedeni s literaturom te su navedeni razlozi poklapanja ili odstupanja.

Abstract (english)

Motivation for studying luminescence in porous silicon is introduced: further microelectronic development and integration with optoelectronics. We presented exciton quantum confinement model in porous silicon as one of the main reasons for photoluminescence. Other causes are also mentioned. Phonon confinement model is presented and its link with Raman spectroscopy which is used as the main characterization technique. Porous silicon electrochemistry is presented along with etching I-V characteristic. New etching cell is presented with detailed description in Appendix. Electrolyte composition is studied with details in Appendix. We described four point probe resistivity measuring technique, samples preparation, I-V measurements and etching procedure. Raman spectroscopy theory is presented. We showed that resistivity variation over the surface of the silicon wafer is negligible to have effect on etching experiments. We studied I-V characteristics in search for ideal etching conditions. It wasn’t possible to see the etching regimes in electrolytes with high hydrofluoric acid concentration. Three series of samples are analyzed. By fitting phonon confinement model on experimental Raman spectra we calculated the size of nano-crystals in porous silicon. The effect of nano-crystal size and phonon peak shift on photoluminescence is studied. Photoluminescence intensity rises as the nano-crystal size is becoming smaller, with no opservable maxima, probably due to porous silicon matrix effect. There was no link between nano-crystal size and photoluminescence energy. We ascribe that to sample oxidation.

• Keywords: poroznisilicij; fotoluminiscencija; kvantno zatočenje ekscitona; kvantno zatočenje fonona; Ramanova spektroskopija; jetkanje fluorovodičnom kiselinom; otpornost silicijeve pločice
• Keywords (english): porous silicon; photoluminescence; exciton quantum confinement; phonon confinement; Raman spectroscopy; hydrofluoric acid etching; four point probe resistivity measurement
• Language: croatian
• URN:NBN: urn:nbn:hr:217:898758
• 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: 2017-07-31 12:28:04