Impact of Small Miscuts of (0001) Sapphire on the Growth of AlxGa1-xN/AlN

AbstractIn this paper, using chemical etching, atomic force microscope (AFM) and High- resolution X-ray diffraction (HRXRD), we report a study of the effect of various small miscuts of (0001) sapphire substrate (<1°) and the way to further improve the material quality. A set of AlN epilayers and AlN/AlxGa1-xN Superlattices (SLs) were grown by Migration-enhanced Metalorganic Chemical Vapor Deposition (MEMOCVD) on vicinal (0001) sapphire substrates. The threading dislocation density was found to be very sensitive to the miscut angles. The etch pit density reduced to 7×106 cm-2 for normal-oriented (0°-off) from the starting value of 7×107 cm-2 for 0.5°-off. We found the surface morphologies can be easily controlled by the different substrate miscut angles. The 1-2 Monolayers (MLs) step flow morphology for normal- oriented substrate changed to step bunches of 10 MLs height for 0.5°-off substrate. Correspondingly, AFM Root Mean Square (RMS) increased from 1.52 to 9.15 Å with a 5um×5um scan. This finding may help enhance the quality of full structure UVLED material and eventually improve the lifetime of UVLEDs.

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MO-CVD GaAs Grown by Direct Deposition on Si

MRS Proceedings ◽

10.1557/proc-91-187 ◽

1987 ◽

Vol 91 ◽

Cited By ~ 4

Author(s):

S. M. Vernon ◽

S. J. Pearton ◽

J. M. Gibson ◽

R. Caruso ◽

C. R. Abernathy ◽

...

Keyword(s):

Chemical Vapor ◽

Gaas Layer ◽

Threading Dislocation ◽

X Ray Diffraction ◽

Si Substrates ◽

Transmission Electron ◽

Activation Data ◽

Threading Dislocation Density ◽

Donor Activity

ABSTRACTGaAs layers were grown directly on misoriented (2° off (100)→[011]) Si substrates by Metalorganic Chemical Vapor Deposition. The threading dislocation density at the surface of 4 μm thick layers was typically 108cm−2, as determined by both preferential etching and transmission electron microscopy. Rapid thermal annealing (900°C, 10s) improved the crystalline quality of the GaAs near the heterointerface while allowing no detectable Si diffusion into this layer. Two deep electron traps were observed in the undoped GaAs, but were present at a low concentration (∼ 1013 cm−3 ). The (400) x-ray diffraction peak width from the GaAs was significantly reduced with increasing GaAs layer thickness, indicating improved material quality. This is supported by Si implant activation data, which shows higher net donor activity in thicker layers.

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Improved Structural Quality and Carrier Decay Times in GaN Epitaxy on SiN and TiN Porous Network Templates

Materials Science Forum ◽

10.4028/www.scientific.net/msf.527-529.1505 ◽

2006 ◽

Vol 527-529 ◽

pp. 1505-1508

Author(s):

Ümit Özgür ◽

Y. Fu ◽

Cole W. Litton ◽

Y.T. Moon ◽

F. Yun ◽

...

Keyword(s):

Chemical Vapor ◽

Structural Quality ◽

Threading Dislocation ◽

X Ray Diffraction ◽

Porous Network ◽

X Ray ◽

Radiative Efficiency ◽

Decay Times ◽

Threading Dislocation Density

Improved structural quality and radiative efficiency were observed in GaN thin films grown by metalorganic chemical vapor deposition on in situ-formed SiN and TiN porous network templates. The room temperature carrier decay time of 1.86 ns measured for a TiN network sample is slightly longer than that for a 200 μm-thick high quality freestanding GaN (1.73 ns). The linewidth of the asymmetric X-Ray diffraction (XRD) (1012) peak decreases considerably with the use of SiN and TiN layers, indicating the reduction in threading dislocation density. However, no direct correlation is yet found between the decay times and the XRD linewidths, suggesting that point defect and impurity related nonradiative centers are the main parameters affecting the lifetime.

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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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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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Structural and Optical Properties of InAsSbBi Grown by Molecular Beam Epitaxy on Offcut GaSb Substrates

Photonics ◽

10.3390/photonics8060215 ◽

2021 ◽

Vol 8 (6) ◽

pp. 215

Author(s):

Rajeev R. Kosireddy ◽

Stephen T. Schaefer ◽

Marko S. Milosavljevic ◽

Shane R. Johnson

Keyword(s):

Molecular Beam Epitaxy ◽

Molecular Beam ◽

Optical Quality ◽

X Ray Diffraction ◽

Interface Quality ◽

Force Microscopy ◽

Atomic Force ◽

Transmission Electron ◽

Lateral Variations

Three InAsSbBi samples are grown by molecular beam epitaxy at 400 °C on GaSb substrates with three different offcuts: (100) on-axis, (100) offcut 1° toward [011], and (100) offcut 4° toward [011]. The samples are investigated using X-ray diffraction, Nomarski optical microscopy, atomic force microscopy, transmission electron microscopy, and photoluminescence spectroscopy. The InAsSbBi layers are 210 nm thick, coherently strained, and show no observable defects. The substrate offcut is not observed to influence the structural and interface quality of the samples. Each sample exhibits small lateral variations in the Bi mole fraction, with the largest variation observed in the on-axis growth. Bismuth rich surface droplet features are observed on all samples. The surface droplets are isotropic on the on-axis sample and elongated along the [011¯] step edges on the 1° and 4° offcut samples. No significant change in optical quality with offcut angle is observed.

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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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Mechanical Interlocking on Leadframe Surface for Bondability of Au Wedge Bond

Materials Science Forum ◽

10.4028/www.scientific.net/msf.857.79 ◽

2016 ◽

Vol 857 ◽

pp. 79-82

Author(s):

Roslina Ismail ◽

Fuaida Harun ◽

Azman Jalar ◽

Shahrum Abdullah

Keyword(s):

Optical Microscope ◽

Bonding Process ◽

Mechanical Interlocking ◽

Average Roughness ◽

Force Microscopy ◽

Atomic Force ◽

Surface Morphologies ◽

Scanning Electron ◽

Effect Of Surface

This work is a contribution towards the understanding of wire bond integrity and reliability in relation to their microstructural and mechanical properties in semiconductor packaging.The effect of surface roughness and hardness of leadframe on the bondability of Au wedge bond still requires detail analysis. Two type of leadframes namely leadframe A and leadframe B were chosen and scanning electron microscope (SEM) and optical microscope were used to inspect the surface morphology of leadframes and the quality of created Au wedge bond after wire bonding process. It was found that there were significant differences in the surface morphologies between these two leadframes. The atomic force microscopy (AFM) which was utilized to measure the average roughness, Ra of lead finger confirms that leadframe A has the highest Ra with value of 166.46 nm compared to that of leadframe B with value of 85.89 nm. While hardness value of different lead finger from the selected leadframe A and B obtained using Vicker microhardness tester are 180.9 VH and 154.2VH respectively.

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Influence of the growth parameters of TiO2 thin films deposited by the MOCVD method

Cerâmica ◽

10.1590/s0366-69132002000100009 ◽

2002 ◽

Vol 48 (305) ◽

pp. 38-42 ◽

Cited By ~ 3

Author(s):

M. I. B. Bernardi ◽

E. J. H. Lee ◽

P. N. Lisboa-Filho ◽

E. R. Leite ◽

E. Longo ◽

...

Keyword(s):

Thin Films ◽

Growth Parameters ◽

Structural Characteristics ◽

Chemical Vapor ◽

X Ray Diffraction ◽

Tio2 Thin Films ◽

X Ray ◽

Force Microscopy ◽

Atomic Force ◽

Deposition Parameters

The synthesis of TiO2 thin films was carried out by the Organometallic Chemical Vapor Deposition (MOCVD) method. The influence of deposition parameters used during growth on the final structural characteristics was studied. A combination of the following experimental parameters was studied: temperature of the organometallic bath, deposition time, and temperature and substrate type. The high influence of those parameters on the final thin film microstructure was analyzed by scanning electron microscopy with electron dispersive X-ray spectroscopy, atomic force microscopy and X-ray diffraction.

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Defect Reduction in Cd1-xZnxTe Epilayers on GaAs Substrates

MRS Proceedings ◽

10.1557/proc-299-191 ◽

1994 ◽

Vol 299 ◽

Author(s):

Saket Chadda ◽

Kevin Malloy ◽

John Reno

Keyword(s):

Threading Dislocation ◽

Full Width ◽

X Ray Diffraction ◽

Defect Reduction ◽

X Ray ◽

Gaas Substrates ◽

Transmission Electron ◽

Threading Dislocation Density ◽

Optimum Period ◽

Bulk Alloys

AbstractCd0.91Zn0.09Te/CdTe multilayers of various period thicknesses were inserted into Cd0.955Zn0.045Te bulk alloys grown on (001) GaAs. The net strain of the multilayer on the underlying Cd0.955Zn0.045Te was designed to be zero. X-ray diffraction full width at half maximum (FWHM) was used as a means to optimize the period thickness of the multilayer. Transmission electron microscopy of the optimum period thickness samples demonstrated four orders of magnitude decrease in the threading dislocation density. Mechanism of bending by equi-strained multilayers is discussed.

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