Istraživanje točkastih defekata u složenim poluvodičkim spojevima mjerenjem apsorpcije rentgenskoga zračenja i teorijom višestrukoga raspršenja

doctoral thesis

• Title (english): Analysis of poin defects in compound semiconducting materials by x-ray absorption spectroscopy and multiple scattering theory
• Author: Robert Peter
• Mentor: Mladen Petravić (mentor)
• Committee member: Krešo Zadro (predsjednik povjerenstva)
• Committee member: Mladen Petravić (član povjerenstva)
• Committee member: Vito Despoja (član povjerenstva)
• Granter: University of Zagreb; Faculty of Science; (Department of Physics); Zagreb
• Defense date and country: 2015-11-24, Croatia
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Physics
• Universal decimal classification (UDC): 53 - Physics

Abstract

U ovoj doktorskoj radnji predstavljamo istraživanje provedeno na poluvodičkim materijalima: borovom nitridu, BN, (heksagonalnoj i kubičnoj fazi te nanocjevčicama), galijevom nitridu, GaN, i cinkovom oksidu, ZnO, koji su bili izlagani niskoenergijskom ionskom bombardiranju, koje stvara niz točkastih defekata u tim materijalima. Karakterizacija nastalih točkastih defekata je provedena spektroskopskim tehnikama baziranim na interakciji rentgenskoga zračenja s materijalom : Spektroskopskom metodom fine strukture apsorpcije rentgenskih zraka blizu rubova ljuski (NEXAFS) i Spektroskopijom fotoelektrona rentgenskim zrakama (XPS). Obje tehnike ispituju elektronsku strukturu materijala i mogu utvrditi nastanak defekta u materijalu, budući da dani defekt stvara nova elektronska stanja u materijalu. Uz navedene eksperimentalne metode, koristili smo i teoriju višestrukoga raspršenja, ugrađenu u računarni kod FEFF, za proračune NEXAFS mjerenja, pomoću kojih se dobivaju informacije o vrsti i položaju defekta u rešetki poluvodiča. U heksagonalnim strukturama BN dušikove praznine, nastale ionskim ozračivanjem, bivaju popunjene atomima kisika prisutnim na površini uzoraka; uz nastajanja borovih i dušikovih intersticijskih atoma. Istovremeno se stvaraju jednostavne duškove molekule: N2 (u BN prahu i nanocjevčicama) i NO (u nanocjevčicama). S druge strane, ionsko bombardiranje GaN stvara dušikove intersticijske atome i dušikova protumjesta u materijalu. Eksperimentalna mjerenja i proračuni pokazuju prisutvo intersticijskih vodikovih atoma u ZnO, koji se vežu s kisikovim atomima ZnO matrice, u anti-vezujućoj konfiguraciji u tek naraslim kristalima, odnosno u konfiguraciji centrirane veze nakon hidratizacije.

Abstract (english)

Studies of point defects in III-N class of semiconductors have attracted great interest in recent decades, as these materials are widely used in new generation of optoelectronic and high frequency microelectronic devices. Namely, point defects (such as vacancies, antisites and interstitial atoms) can directly influence optical or electrical properties of semiconductor materials. For instance, native n-type conductivity and luminescence properties of gallium nitride and zinc oxide can be related to vacancies or interstitial atoms in their structures. Also, one of the interesting phenomenon related to nitrogen based semiconductors is the creation of interstitial molecular nitrogen (N2) during growth or processing of materials, and the question of physical properties of N2 molecule trapped in semiconductor matrix. Point defects have high energy formation in nitrogen related semiconductors (> 2eV), limiting the concentration of native defects to small values. Thus, exploration of point defect requires artificial creation of defects in materials. It is shown that the low-energy ion bombardment presents an efficient method to introduce various defects in semiconductor structures. In addition, ion irradiation is widely used in semiconductor industry in various processes (such as ion implantation, surface preparation or plasma etching), so studying the interaction of energetic ions with semiconductor matrix, in addition of being scientificaly interesting, is also technologically important.

• Keywords: točkasti defekti; ionsko bombardiranje; NEXAFS; FEFF; XPS
• Keywords (english): point defects; ion bombardment; NEXAFS; FEFF; XPS
• Language: croatian
• URN:NBN: urn:nbn:hr:217:918197
• Study programme: Title: Physics; Study programme type: university; Study level: postgraduate; Academic / professional title: doktor/doktorica znanosti, područje prirodnih znanosti, polje fizika (doktor/doktorica znanosti, područje prirodnih znanosti, polje fizika)
• Type of resource: Text
• Extent: 124 str.
• File origin: Born digital
• Access conditions: Open access
• Created on: 2017-08-25 08:00:11