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Position-controlled selective area growth of Ga-polar GaN nanocolumns by molecular beam epitaxy

A versatile approach towards semipolar GaN and the characterization of single nanocolumns

dc.contributor.advisorRizzi, Angela Prof. Dr.
dc.contributor.authorUrban, Arne
dc.titlePosition-controlled selective area growth of Ga-polar GaN nanocolumns by molecular beam epitaxyde
dc.title.alternativeA versatile approach towards semipolar GaN and the characterization of single nanocolumnsde
dc.contributor.refereeDaudin, Bruno Dr.
dc.subject.gokPhysik (PPN621336750)de
dc.description.abstractengThis thesis focuses on the position-controlled selective area growth of Ga-polar GaN nanocolumns by molecular beam epitaxy. Part I of this thesis reviews the theoretical background which is considered to be vital for the understanding of this thesis. Furthermore, the performed research will be motivated in detail. Chapter 2 summarizes important basic physical properties of GaN. General aspects which are of importance concerning the growth of GaN by molecular beam epitaxy are discussed in Chapter 3. The growth of GaN nanocolumns by molecular beam epitaxy will be topic of discussion in Chapter 4. The last chapter of this part (Chapter 5) summarizes the patterning and characterization techniques which have been used in this thesis. Part II presents results on the selective area growth of GaN nanocolumns, as well as on the structural and optical properties of these columns. Chapter 6 describes the route towards successful selective area growth in detail and summarizes optimized growth conditions. In the following Chapter 7, the selective area growth is investigated. First, a kinetic description, with focus on Ga adatom surface processes which have a strong impact on the nanocolumn axial growth rate, will be used. In addition, it will be shown that the approach of selective area growth is indeed suited to obtain arrayed, semipolar GaN templates. The second section of this chapter presents results on the morphology of the nanocolumns and the polarity, i.e. whether the crystallographic growth direction is along [0001] or antiparallel to this direction along [000-1]. The last section of this chapter discusses the distinct morphology of the GaN columns in the framework of equilibrium thermodynamics. Chapter 8 presents results on the structural properties of the columns. These comprise the crystal quality in general, and the presence of dislocations and extended defects. In addition, the growth of III−N semipolar multi-quantum wells will be presented. The optical properties of the selectively grown GaN nanocolumns will be assessed in Chapter 9 and furthermore correlated with the structural properties. Single GaN nanocolumns are subject of investigation, as well as ensembles of nanocolumns. Part III summarizes the main achievements and conclusions of this work. Based on the results of this thesis, an outlook provides proposals on the future research on selective area growth of GaN nanocolumns by molecular beam
dc.contributor.coRefereeKrebs, Hans-Ulrich Prof. Dr.
dc.subject.engmolecular beam epitaxyde
dc.subject.enggallium nitridede
dc.subject.engselective area growthde
dc.subject.engtransmission electron microscopyde
dc.subject.engextended defectsde
dc.subject.engthreading dislocationsde
dc.affiliation.instituteFakultät für Physikde

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