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Article
On the Light Emission in GaN Based Heterostructures at High Injection
For light emitting diodes (LEDs) to be used for general lighting, high efficiencies would need to be retained at high injection levels to meet the intensity and efficiency requirements. In this regard, it is i...
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Chapter and Conference Paper
Molecular Interactions on InxGa1−xN
Atomic force microscopy in solution offers a platform for assessing interactions on chemically modified surfaces. In this study a biologically relevant molecule, an amino acid, is adsorbed onto a compositional...
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Article
Hydride Vapour Phase Homoepitaxial Growth of GaN on MOCVD-Grown ‘Templates’
We report on an improved quality of thick HVPE-GaN grown on MOCVD-GaN ‘template’ layers compared to the material grown directly on sapphire. The film-substrate interface revealed by cathodoluminescence measure...
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Article
Near-Infrared Absorption in Lattice-Matched AlInN/GaN and Strained AlGaN/GaN Heterostructures Grown by MBE on Low-Defect GaN Substrates
We have investigated near-infrared absorption and photocurrent in lattice-matched AlInN/GaN and strained AlGaN/GaN heterostructures grown by molecular-beam epitaxy (MBE) on low-defect GaN substrates for infrar...
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Article
Domain Structure of Thick GaN Layers Grown by Hydride Vapor Phase Epitaxy
The crystal structure and surface morphology of hydride vapour phase epitaxy grown thick (12-105 μm) GaN layers have been investigated as a function of growth rate using several structure sensitive techniques ...
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Article
Physical Properties of AlGaN/GaN Heterostructures Grown on Vicinal Substrates
We report on the growth of Al0.25Ga0.75N/GaN heterostructures grown on low dislocation density vicinal surfaces of semi-insulating c-axis GaN substrates. Atomic force microscopy (AFM), photoluminescence (PL), cat...
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Chapter and Conference Paper
Interaction of Stacking Faults in Wurtzite a-Plane GaN on r-Plane Sapphire
The defect structure in a-plane GaN films grown on r-plane sapphire distinguishes itself significantly from the one found in c-plane GaN. Transmission electron microscopy studies on a-plane GaN films grown by hyd...
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Article
High pressure annealing of HVPE GaN free-standing films: redistribution of defects and stress
The effect of high temperature, high pressure annealing on morphology, optical and structural properties of free-standing GaN films grown by hydride vapor phase epitaxy is studied. The annealing is found to ch...
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Article
Hydride vapor-phase epitaxial GaN thick films for quasi-substrate applications: Strain distribution and wafer bending
The strain distribution in thick hydride vapor-phase epitaxial (HVPE)-GaN layers grown on metal-organic vapor-phase epitaxial GaN templates was studied by means of photoluminescence, x-ray map**, and lattice...
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Article
Strain evolution and phonons in AlN/GaN superlattices
AlN/GaN superlattices (SLs) with different periods grown on GaN buffer layers were studied by infrared spectroscopic ellipsometry (IRSE), Raman scattering (RS) and highresolution reciprocal space map** (RSM)...
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Article
Formation and dissociation of hydrogen-related defect centers in Mg-doped GaN
Moderately and heavily Mg-doped GaN were studied by a combination of post-growth annealing processes and electron beam irradiation techniques during cathodoluminescence (CL) to elucidate the chemical origin of...
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Article
Polarization-dependent spectroscopy of the near-bandgap excitonic emission in free standing GaN
We report a comparative study of the exciton emission in free standing HVPE layer for all polarization configurations. A noticeable difference between the emission spectra polarized perpendicular and parallel ...
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Article
Effect of carrier concentration on the microhardness of GaN layers
The paper presents a microhardness study of thick crack-free hydride vapor phase epitaxial GaN layers (not intentionally doped), and of thin metal-organic vapor phase epitaxial (MOVPE) GaN layers (undoped and ...
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Article
Phonon-assisted exciton luminescence in GaN layers grown by MBE and chloride-hydride VPE
Optical properties of GaN layers grown by the molecular-beam epitaxy (MBE) and chloride-hydride vapor-phase epitaxy (CHVPE) have been studied, and the quality of two types of samples has been compared. The pho...
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Article
Characterization of Red Emission in Nominally Undoped Hydride Vapor Phase Epitaxy GaN
We report characterization of the red emission band in hydride vapor phase epitaxial GaN using cathodoluminescence spectroscopy and imaging and time-resolved photoluminescence. The observed properties of the e...
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Article
A new mechanism in the growth process of GaN by HVPE
Experimental results obtained in two different HVPE reactors are analyzed and compared to the theoretical curves, taking into account the surface kinetics, the mass transfer, and parasitic deposition on the gl...
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Article
Hydride Vapour Phase Homoepitaxial Growth of GaN on MOCVD-Grown ‘Templates’
We report on an improved quality of thick HVPE-GaN grown on MOCVD-GaN ‘template’ layers compared to the material grown directly on sapphire. The film-substrate interface revealed by cathodoluminescence measure...
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Article
Domain Structure of Thick GaN Layers Grown by Hydride Vapor Phase Epitaxy
The crystal structure and surface morphology of hydride vapour phase epitaxy grown thick (12-105 μm) GaN layers have been investigated as a function of growth rate using several structure sensitive techniques ...
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Chapter
Electron State Symmetries and Optical Selection Rules in the (GaAs)m(AlAs)n Superlattices Grown along the [001], [110], and [111] Directions
Recently, using the method of induced band representations of space groups, the full electron state symmetries and the selection rules for optical transitions in the (GaAs)m(AlAs)n superlattices (SL’s) were studi...
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Article
Characterization of MOVPE-Grown GaAs layers by C—V analysis
