GaN growth on sapphire by MOCVD - Material for HEMT structures

Contains fulltext : 27418.pdf (publisher's version ) (Open Access)This thesis focuses on growth and basic characterization of AlGaN/GaN based high electron mobility structures. In order to provide theoretical background for the presented research, the basic physical properties of III-V nitrides and the characteristics of the HEMT structures are discussed. Additionally, properties of substrates used for GaN epitaxy are describedRU, 05 april 2006Promotor : Larsen, P.K. Co-promotor : Hageman, P.R.VI, 115 p

Statistical photoluminescence of dislocations and associated defects in heteroepitaxial GaN grown by metal organic chemical vapor deposition

Contains fulltext : 33011.pdf (publisher's version ) (Open Access

Influence of sapphire annealing in trimethylgallium atmosphere on GaN epitaxy by MOCVD

Contains fulltext : 32637.pdf (publisher's version ) (Closed access

Method for HVPE growth of thick crack-free GaN layers

Contains fulltext : 35642.pdf (publisher's version ) (Closed access

Influence of sapphire annealing in trimethylaluminum atmosphere on GaN epitaxy by MOCVD

Contains fulltext : 72198.pdf (publisher's version ) (Closed access)7 p

Influence of the nucleation layer morphology and epilayer structure on the resistivity of GaN films grown on c-plane sapphire by MOCVD

Contains fulltext : 32639.pdf (publisher's version ) (Closed access)The influence of hydrogen and nitrogen carrier gases used during the preparation of the nucleation layer on the structural and electrical properties of GaN layers has been investigated. The GaN were grown on sapphire substrates using metal organic chemical vapor deposition. The nucleation layer morphology strongly depends on the carrier gas affecting the electrical properties of GaN epitaxial films through changes of the ratio of edge to mixed and screw-type threading dislocations. X-ray diffractometry, X-ray reflectometry, atomic force microscopy, and defect selective etching were employed to study the structural properties of both the nucleation layer and the GaN epilayers deposited on top of this. It is found that the density of edge-type dislocations determines the resistivity of GaN epilayers and that one key factor for varying the density of these dislocations is the morphology of the nucleation layer, i.e. the morphology of the GaN epilayer can be controlled by the type of carrier gas used in the preparation of the nucleation layer. The electrical resistivity of our GaN epilayers is typically about 0.5Omegacm and more than 3 x 10(4) Omega cm with nucleation layers grown using hydrogen and nitrogen carrier gases, respectively. (C) 2004 Elsevier B.V. All rights reserved

Resistivity control of unintentionally doped GaN films

Contains fulltext : 32935.pdf (publisher's version ) (Closed access

The effect of HVPE reactor geometry on GaN growth rate - experiments versus simulations

Contains fulltext : 60160.pdf (publisher's version ) (Closed access)In the study, presented in this paper, the growth of GaN layers by Hydride vapour phase epitaxy was investigated both experimentally and numerically. Modelling the flows in the reactor, combined with basic chemistry, gives a good approximation to the actual growth experiments. It was found that small changes in the reactor geometry, e.g. the inlet of GaCl, have a large effect on the growth rate as well as on the uniformity of the growth. (C) 2004 Elsevier B.V. All rights reserved

Below band-gap transitions in an AIGaAN/GaN transistor heterostructure observed by photoreflectance spectroscopy.

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Influence of the substrate misorientation of 4H-SiC substrates on the morphology and crack formation in hetero epitaxial MOCVD grown GaN epilayers by MOCVD

Contains fulltext : 32640.pdf (publisher's version ) (Closed access)4 p