High Power 330 nm AlInGaN UV LEDs in the High Injection Regime

ABSTRACTWe report on the growth and testing of the light emitting diode structures incorporating quaternary AlInGaN active region with an emission wavelength of 330 nm. Small area circular devices were fabricated, yielding the output power of 110 μW measured with a bare-chip configuration in a high current injection regime (8 kA/cm2 for a 20 μm diameter device). Structural properties of the constituent epitaxial layers were evaluated by atomic force microscopy and transmission electron microscopy, resulting in the observation of two-dimensional growth morphologies of AlN and AlGaN, and the estimate of threading dislocation densities in the low 109 cm-2 range in the structures grown on sapphire substrates.

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Defect-Engineered Graded GexSi1-x Buffers on Si (001) with Extreme Low Threading Dislocation Density

MRS Proceedings ◽

10.1557/proc-378-141 ◽

1995 ◽

Vol 378 ◽

Cited By ~ 2

Author(s):

G. Kissinger ◽

T. Morgenstern ◽

G. Morgenstern ◽

H. B. Erzgräber ◽

H. Richter

Keyword(s):

Electron Microscopy ◽

Transmission Electron Microscopy ◽

Atomic Force Microscopy ◽

Dislocation Density ◽

Threading Dislocation ◽

Force Microscopy ◽

Atomic Force ◽

Transmission Electron ◽

Dislocation Densities ◽

Threading Dislocation Density

AbstractStepwise equilibrated graded GexSii-x (x≤0.2) buffers with threading dislocation densities between 102 and 103 cm−2 on the whole area of 4 inch silicon wafers were grown and studied by transmission electron microscopy, defect etching, atomic force microscopy and photoluminescence spectroscopy.

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The effect of periodic silane burst on the properties of GaN on Si (111) substrates

MRS Proceedings ◽

10.1557/proc-831-e3.33 ◽

2004 ◽

Vol 831 ◽

Author(s):

K. Y. Zang ◽

S. J. Chua ◽

C. V. Thompson ◽

L. S. Wang ◽

S. Tripathy ◽

...

Keyword(s):

Chemical Vapor ◽

Buffer Layers ◽

Threading Dislocation ◽

X Ray Diffraction ◽

Force Microscopy ◽

Atomic Force ◽

Transmission Electron ◽

Dislocation Densities ◽

Gan On Si ◽

Aln Buffer

ABSTRACTThe periodic silane burst technique was employed during metalorganic chemical vapor deposition of epitaxial GaN on AlN buffer layers grown on Si (111). Periodic silicon delta doping during growth of both the AlN and GaN layers led to growth of GaN films with decreased tensile stresses and decreased threading dislocation densities, as well as films with improved quality as indicated by x-ray diffraction, micro-Raman spectroscopy, atomic force microscopy, and transmission electron microscopy. The possible mechanism of the reduction of tensile stress and the dislocation density is discussed in the paper.

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High Quality AlN Layer Grown on Patterned Sapphire Substrates by Hydride Vapor-Phase Epitaxy: A Route for Cost Efficient AlN Templates for Deep Ultraviolet Light Devices

Journal of Nanoscience and Nanotechnology ◽

10.1166/jnn.2021.19258 ◽

2021 ◽

Vol 21 (9) ◽

pp. 4881-4885

Author(s):

Seung-Jae Lee ◽

Seong-Ran Jeon ◽

Young Ho Song ◽

Young-Jun Choi ◽

Hae-Gon Oh ◽

...

Keyword(s):

Vapor Phase ◽

Vapor Phase Epitaxy ◽

Hydride Vapor Phase Epitaxy ◽

Threading Dislocation ◽

Sapphire Substrates ◽

Transmission Electron ◽

Dislocation Densities ◽

Order Of Magnitude ◽

Cost Efficient ◽

Patterned Sapphire Substrates

We report the characteristics of AlN epilayers grown directly on cylindrical-patterned sapphire substrates (CPSS) by hydride vapor-phase epitaxy (HVPE). To evaluate the effect of CPSS, we analyzed the threading dislocation densities (TDDs) of AlN films grown simultaneously on CPSS and flat sapphire substrate (FSS) by transmission electron microscopy (TEM). The corresponding TDD is measured to be 5.69 x 108 cm−2 for the AlN sample grown on the CPSS that is almost an order of magnitude lower than the value of 3.43 × 109 cm−2 on the FSS. The CPSS contributes to reduce the TDs originated from the AlN/sapphire interface via bending the TDs by lateral growth during the coalescence process. In addition, the reduction of direct interface area between AlN and sapphire by CPSS reduce the generation of TDs.

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Colloidal quantum dot active layer electroluminescence in a solid GaN matrix

MRS Proceedings ◽

10.1557/proc-0891-ee03-06 ◽

2005 ◽

Vol 891 ◽

Author(s):

Jennifer Pagan ◽

Edward Stokes ◽

Kinnari Patel ◽

Casey Burkhart ◽

Mike Ahrens

Keyword(s):

Active Layer ◽

Light Emitting Diode ◽

Cdse Quantum Dots ◽

Light Emitting ◽

Force Microscopy ◽

Turn On ◽

Atomic Force ◽

Transmission Line Method ◽

Gan Led ◽

Colloidal Quantum Dot

ABSTRACTIn this paper the preliminary results of incorporating a novel active layer into a GaN light emitting diode (LED) are discussed. Integration of colloidal CdSe quantum dots into a GaN LED active layer is demonstrated. The conductivity of the overgrowth was examined by circular transmission line method (CTLM). Effects on surface roughness due to the active layer incorporation are examined using atomic force microscopy (AFM). LED test devices were fabricated and electroluminescence was demonstrated, the devices exhibit higher turn-on voltages than would be expected for a CdSe active layer.

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SiH4 exposure of GaN surfaces: A useful tool for highlighting dislocations

MRS Proceedings ◽

10.1557/proc-0892-ff24-06 ◽

2005 ◽

Vol 892 ◽

Author(s):

Rachel Oliver ◽

Menno J. Kappers ◽

Joy Sumner ◽

Ranjan Datta ◽

Colin J. Humphreys

Keyword(s):

Atomic Force Microscopy ◽

Vapour Phase ◽

Threading Dislocation ◽

Vapour Phase Epitaxy ◽

Force Microscopy ◽

Atomic Force ◽

Dislocation Densities ◽

Metal Organic ◽

Organic Vapour

AbstractFast-turnaround, accurate methods for the assessment of threading dislocation densities in GaN are an essential research tool. Here, we present an in-situ surface treatment for use in MOVPE (metal-organic vapour phase epitaxy) growth, in which GaN is exposed to a SiH4 flux at 860 °C in the presence of NH3. Subsequent characterisation by atomic force microscopy shows that the treatment is effective in increasing edge and mixed/screw dislocation pit sizes on both n- and p-type material, and on partially coalesced GaN layers.

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A Refined Model For Threading Dislocation Filtering In InxGa1−xAs/GaSAs Epitaxial Layers

MRS Proceedings ◽

10.1557/proc-442-473 ◽

1996 ◽

Vol 442 ◽

Author(s):

G. Macpherson ◽

P. J. Goodhew

Keyword(s):

Large Scale ◽

Critical Thickness ◽

Thin Layers ◽

Threading Dislocation ◽

Threading Dislocations ◽

Refined Model ◽

Force Microscopy ◽

Atomic Force ◽

Dislocation Densities ◽

High Level

AbstractA model is presented for the filtering of threading dislocations in InxGa1−xAs/GaAs epitaxial single layers by accurate control of the layer thickness. The model developed differs from previous models since the InxGa1−xAs growth is restricted to less than ten times the Matthews and Blakeslee critical thickness (hc) where the asymmetry in the [110] and [110] dislocation densities is the greatest. Beyond this thickness it is shown that the removal or annihilation of threading dislocations (TDs) in the epilayer is more than offset by the introduction of new TDs from spiral and Frank-Read type sources. Results from strain sensitive etching with CrO3 aqueous solutions show that the TD density can be reduced by up to a factor of ten below that found in the substrate. Atomic force microscopy shows that these thin layers maintain a high level of surface quality with an absence of striations. Evidence is also shown that this type of defect etching is suitable for revealing large scale dislocation blocking in samples that have been grown significantly beyond 10hc.

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BaTiO3 Waveguides on MgO Buffered-Sapphire Single Crystals

MRS Proceedings ◽

10.1557/proc-597-183 ◽

1999 ◽

Vol 597 ◽

Cited By ~ 2

Author(s):

Judit G. Lisoni ◽

M. Siegert ◽

C. H. Lei ◽

C. L. Jia ◽

J. Schubert ◽

...

Keyword(s):

Optical Waveguides ◽

Ferroelectric Thin Film ◽

X Ray Diffraction ◽

Epitaxial Relationship ◽

Rocking Curve ◽

Force Microscopy ◽

Sapphire Substrates ◽

Atomic Force ◽

Transmission Electron ◽

Good Crystalline Quality

AbstractWithin our program to develop ferroelectric thin film optical waveguides, we have studied the growth of epitaxial waveguides BaTiO3 on r-plane sapphire substrates with a MgO buffer layer. The films were prepared by pulsed laser deposition (PLD). Their structural properties were studied by X-ray diffraction (XRD), transmission electron microscopy (TEM), Rutherford backscattering (RBS) in random and channeling (RBS-c) configuration and atomic force microscopy (AFM). They displayed good crystalline quality, characterized by an RBS-c minimum yield of about 4–6%, a full width at half maximum (FWHM) of the XRD rocking curve measurement of the BaTiO3(200) reflection of 0.32° and a rms roughness of 1.2 nm in a film of ∼ 1.0 μm thickness. The epitaxial relationship was found to be BaTiO3(100) // MgO(100) // A12O3(1102). The refractive index, the birefringence and the optical losses have been measured.

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Structural and Stress Properties of AlGaN Epilayers Grown on AlN-Nanopatterned Sapphire Templates by Hydride Vapor Phase Epitaxy

Nanomaterials ◽

10.3390/nano8090704 ◽

2018 ◽

Vol 8 (9) ◽

pp. 704 ◽

Cited By ~ 3

Author(s):

Chi-Tsung Tasi ◽

Wei-Kai Wang ◽

Sin-Liang Ou ◽

Shih-Yung Huang ◽

Ray-Hua Horng ◽

...

Keyword(s):

Vapor Phase ◽

Sapphire Substrate ◽

Vapor Phase Epitaxy ◽

Hydride Vapor Phase Epitaxy ◽

Threading Dislocation ◽

Force Microscopy ◽

Al Content ◽

Atomic Force ◽

Transmission Electron ◽

Biaxial Tensile Stress

In this paper, we report the epitaxial growth and material characteristics of AlGaN (Al mole fraction of 10%) on an AlN/nanopatterned sapphire substrate (NPSS) template by hydride vapor phase epitaxy (HVPE). The crystalline quality, surface morphology, microstructure, and stress state of the AlGaN/AlN/NPSS epilayers were investigated using X-ray diffraction (XRD), atomic force microscopy (AFM), and transmission electron microscopy (TEM). The results indicate that the crystal quality of the AlGaN film could be improved when grown on the AlN/NPSS template. The screw threading dislocation (TD) density was reduced to 1.4 × 109 cm−2 for the AlGaN epilayer grown on the AlN/NPSS template, which was lower than that of the sample grown on a flat c-plane sapphire substrate (6.3 × 109 cm−2). As examined by XRD measurements, the biaxial tensile stress of the AlGaN film was significantly reduced from 1,187 MPa (on AlN/NPSS) to 38.41 MPa (on flat c-plane sapphire). In particular, an increase of the Al content in the overgrown AlGaN layer was confirmed by the TEM observation. This could be due to the relaxation of the in-plane stress through the AlGaN and AlN/NPSS template interface.

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Dislocation reduction with quantum dots in GaN grown on sapphire substrates by molecular beam epitaxy

MRS Proceedings ◽

10.1557/proc-722-k1.5 ◽

2002 ◽

Vol 722 ◽

Cited By ~ 1

Author(s):

David J. Smith ◽

Daming Huang ◽

Michael A Reshchikov ◽

Feng Yun ◽

T. King ◽

...

Keyword(s):

Electron Microscopy ◽

Transmission Electron Microscopy ◽

Atomic Force Microscopy ◽

Molecular Beam ◽

Buffer Layers ◽

Force Microscopy ◽

Sapphire Substrates ◽

Atomic Force ◽

Transmission Electron ◽

Aln Buffer

AbstractWe have investigated a novel approach for improving GaN crystal quality by utilizing a stack of quantum dots (QDs) in GaN grown on sapphire substrates by molecular beam epitaxy. The GaN films were grown on GaN/AlN buffer layers containing multiple QDs and characterized using x-ray diffraction, photoluminescence, atomic force microscopy, and transmission electron microscopy. The density of the dislocations in the films was determined by defect delineation wet chemical etching and atomic force microscopy. It was found that the insertion of a set of multiple GaN QD layers in the buffer layer effectively reduced the density of the dislocations in the epitaxial layers. As compared to a density of ∼1010cm-2in typical GaN films grown on AlN buffer layers, a density of ∼3×107cm-2was demonstrated in GaN films grown with the QD layers. Transmission electron microscopy observations confirmed termination of threading dislocations by the QD layers.

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On the Study of Dislocation Density in MBE GaSb-Based Structures

Crystals ◽

10.3390/cryst10121074 ◽

2020 ◽

Vol 10 (12) ◽

pp. 1074

Author(s):

Agata Jasik ◽

Dariusz Smoczyński ◽

Iwona Sankowska ◽

Andrzej Wawro ◽

Jacek Ratajczak ◽

...

Keyword(s):

High Resolution ◽

Dislocation Density ◽

Measurement Techniques ◽

Threading Dislocation ◽

X Ray Diffraction ◽

Gaas Sample ◽

Force Microscopy ◽

Atomic Force ◽

Transmission Electron ◽

Threading Dislocation Density

The results of the study on threading dislocation density (TDD) in homo- and heteroepitaxial GaSb-based structures (metamorphic layers, material grown by applying interfacial misfit array (IMF) and complex structures) deposited using molecular beam epitaxy are presented. Three measurement techniques were considered: high-resolution x-ray diffraction (HRXRD), etch pit density (EPD), and counting tapers on images obtained using atomic force microscopy (AFM). Additionally, high-resolution transmission electron microscopy (HRTEM) was used for selected samples. The density of dislocations determined using these methods varied, e.g., for IMF-GaSb/GaAs sample, were 6.5 × 108 cm−2, 2.2 × 106 cm−2, and 4.1 × 107 cm−2 obtained using the HRXRD, EPD, and AFM techniques, respectively. Thus, the value of TDD should be provided together with information about the measurement method. Nevertheless, the absolute value of TDD is not as essential as the credibility of the technique used for optimizing material growth. By testing material groups with known parameters, we established which techniques can be used for examining the dislocation density in GaSb-based structures.

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