Journal ArticleDOI
Dislocation mediated surface morphology of GaN
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TLDR
In this article, the surface morphology of GaN films grown by metalorganic chemical vapor deposition (MOCVD) and molecular beam epitaxy (MBE) was studied using atomic force microscopy (AFM).Abstract:
The surfaces of GaN films grown by metalorganic chemical vapor deposition (MOCVD) and molecular beam epitaxy (MBE) were studied using atomic force microscopy (AFM). Due to the high dislocation densities in the films (108 cm−2), the typical surface morphologies of layers grown by both techniques were dominated by three dislocation mediated surface structures—pinned steps, spiral hillocks, and surface depressions. The characteristics of these surface structures were found to depend on growth technique (MOCVD vs MBE) and the group-III to group-V ratio used in the growth of MBE GaN films. Pinned steps, created by the intersections of mixed character dislocations with the free surface, were found on all GaN films. The pinned steps were observed to be predominantly straight on the MOCVD GaN and curved into spiral hillock formations on the MBE GaN. Spiral growth hillocks form when pinned steps grow outward and around the dislocation under step-flow growth conditions. The tightness of the spiral hillocks on MBE G...read more
Citations
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Journal ArticleDOI
Growth of high-quality N-polar GaN on bulk GaN by plasma-assisted molecular beam epitaxy
Christian Wurm,Elaheh Ahmadi,Feng Wu,Nirupam Hatui,Stacia Keller,James S. Speck,Umesh K. Mishra +6 more
TL;DR: In this paper, the surface impurities play a major role in the formation of surface-pits in epitaxially grown GaN films, and a 2'nm coherently strained AlN initiation layer is used to capture impurities on the substrate surface.
Journal ArticleDOI
Stress control in thick AlN/c-Al 2 O 3 templates grown by plasma-assisted molecular beam epitaxy
TL;DR: In this article, the authors studied the stress evolution in up to 3 µm thick AlN templates, comprising ∼65 nm thick ALN nucleation layers (NLs) and thick buffer layers (BLs), grown using different growth modes and conditions by plasma-assisted molecular beam epitaxy (PA MBE) on c-Al2O3.
Journal ArticleDOI
Evolution of the surface morphology of AlN epitaxial film by HVPE
TL;DR: In this paper, the evolution of the surface morphologies of AlN films grown by hydride vapor was studied using atomic force microscopy (AFM) using phase epitaxy (HYPE).
Journal ArticleDOI
Surface and dislocation investigation of planar GaN formed by crystal reformation of nanowire arrays
Jovana Colvin,Rafal Ciechonski,Filip Lenrick,Olof Hultin,Maryam Khalilian,Anders Mikkelsen,Anders Gustafsson,Lars Samuelson,Rainer Timm,B. Jonas Ohlsson +9 more
TL;DR: In this paper, a process of forming monolithic GaN surface from an ordered nanowire array by means of material redistribution is presented, referred to as reformation, is performed in a conventional MOVPE crystal growth system with the gallium supply turned off and allows a crystal nanostructure to change shape according to differences in surface energies between its facets.
Journal ArticleDOI
Degradation Mechanism of Crystalline Quality and Luminescence in In0.42Ga0.58N/GaN Double Heterostructures with Porous InGaN Layer
Jianxun Liu,Hongwei Liang,Xiantong Zheng,Yang Liu,Xiaochuan Xia,Qasim Abbas,Huolin Huang,Rensheng Shen,Yingmin Luo,Guotong Du +9 more
TL;DR: In this article, a high-angle annular dark field scanning transmission electron microscopy revealed that the In0.42Ga0.58N layer features a porous structure consisting of multifaceted voids with a density of 109 cm-2 and an average diameter of 74.6 nm.
References
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Journal ArticleDOI
The Growth of Crystals and the Equilibrium Structure of their Surfaces
TL;DR: In this paper, it was shown that the rate of growth of a surface containing dislocations is proportional to the square of the supersaturation for low values and to the first power for high values of the latter.
Book
Organometallic Vapor-Phase Epitaxy: Theory and Practice
TL;DR: The OMVPE process as mentioned in this paper is a process of physical processes occurring on the surface of the Earth, and it has been used in many applications in the computer science community, e.g. superlattice structures.
Journal ArticleDOI
Role of threading dislocation structure on the x‐ray diffraction peak widths in epitaxial GaN films
B. Heying,X. H. Wu,Stacia Keller,Youli Li,D. Kapolnek,Bernd Keller,Steven P. DenBaars,James S. Speck +7 more
TL;DR: In this article, the authors demonstrate that the anomalously low (002) x-ray rocking curve widths for epitaxial hexagonal GaN films on (001) sapphire are a result of a specific threading dislocation geometry.
Book
Physics of Semiconductors and Their Heterostructures
TL;DR: In this article, the authors present a free electron picture of Crystalline Structures and a wave diffraction from Crystals, and then show how to use it for high field transport in Semiconductors.