Effect of screw dislocation density on optical properties in n-type wurtzite GaN

2007 ◽  
Vol 101 (2) ◽  
pp. 023516 ◽  
Author(s):  
Jeong Ho You ◽  
H. T. Johnson
Keyword(s):  
Optical Properties ◽  
Dislocation Density ◽  
Screw Dislocation ◽  
Screw Dislocation Density

Characterization of Porous SiC Substrates and of the Epilayer Structures Grown on Them

2002 ◽  
Vol 742 ◽  
Author(s):  
Balaji Raghothamachar ◽  
Jie Bai ◽  
William M. Vetter ◽  
Perena Gouma ◽  
Michael Dudley ◽  
...  
Keyword(s):  
Dislocation Density ◽  
Optical Microscopy ◽  
Epitaxial Growth ◽  
Screw Dislocation ◽  
Pore Morphology ◽  
Porous Substrate ◽  
X Ray ◽  
Porous Sic ◽  
Screw Dislocation Density

ABSTRACTPorous 6H-SiC and 4H-SiC wafers formed by anodization have been characterized in this study prior to and following the CVD deposition of SiC epitaxial layers, using a combination of synchrotron white beam x-ray topography (SWBXT), SEM, TEM and optical microscopy. Under the high temperatures employed during epitaxial growth, a significant change in pore morphology occurs. While no evidence of reduced screw dislocation density in the epilayers is obtained, a small tilt of the epilayers with respect to the porous substrate observed on x-ray topographs could play a role in limiting penetration of defects from the substrate.

Correlation of threading screw dislocation density to GaN 2‐DEG mobility

2014 ◽  
Vol 50 (23) ◽  
pp. 1722-1724 ◽  
Author(s):  
J.K. Hite ◽  
P. Gaddipati ◽  
D.J. Meyer ◽  
M.A. Mastro ◽  
C.R. Eddy
Keyword(s):  
Dislocation Density ◽  
Screw Dislocation ◽  
Screw Dislocation Density

scholarly journals Study of Edge and Screw Dislocation Density in GaN/Al2O3 Heterostructure

Materials ◽  
2019 ◽  
Vol 12 (24) ◽  
pp. 4205 ◽  
Author(s):  
Vladimir Lucian Ene ◽  
Doru Dinescu ◽  
Iulia Zai ◽  
Nikolay Djourelov ◽  
Bogdan Stefan Vasile ◽  
...  
Keyword(s):  
High Resolution ◽  
Dislocation Density ◽  
Screw Dislocation ◽  
Diffusion Length ◽  
Correlation Lengths ◽  
Transmission Electron ◽  
Aln Buffer ◽  
Gan Film ◽  
Defect Densities ◽  
Screw Dislocation Density

This study assesses the characteristics (edge and screw dislocation density) of a commercially available GaN/AlN/Al2O3 wafer. The heterostructure was evaluated by means of high-resolution X-ray diffraction (HR-XRD), high-resolution transmission electron microscopy (HR-TEM), and Doppler-Broadening Spectroscopy (DBS). The results were mathematically modeled to extract defect densities and defect correlation lengths in the GaN film. The structure of the GaN film, AlN buffer, Al2O3 substrate and their growth relationships were determined through HR-TEM. DBS studies were used to determine the effective positron diffusion length of the GaN film. Within the epitaxial layers, defined by a [GaN P 63 m c (0 0 0 2) || P 63 m c AlN (0 0 0 2) || (0 0 0 2) R 3 ¯ c Al2O3] relationship, regarding the GaN film, a strong correlation between defect densities, defect correlation lengths, and positron diffusion length was assessed. The defect densities ρ d e = 6.13 × 1010 cm−2, ρ d s = 1.36 × 1010 cm−2, along with the defect correlation lengths Le = 155 nm and Ls = 229 nm found in the 289 nm layer of GaN, account for the effective positron diffusion length Leff~60 nm.

The Use of AlN Interlayers to Improve GaN Growth on A-Plane Sapphire

1999 ◽  
Vol 587 ◽  
Author(s):  
D.D. Koleske ◽  
M.E. Twigg ◽  
A.E. Wickenden ◽  
R.L. Henry ◽  
R.J. Gorman ◽  
...  
Keyword(s):  
Dislocation Density ◽  
Screw Dislocation ◽  
Film Growth ◽  
Fold Increase ◽  
Large Area ◽  
Cross Sectional ◽  
Acceptor Concentration ◽  
Si Doped ◽  
Gan Film ◽  
Screw Dislocation Density

AbstractThe lack of a suitable, lattice matched substrate for the growth of the group III nitrides typically restricts GaN film growth to substrates such as sapphire or SiC, despite the large lattice and thermal mismatch. With the use of AlN or GaN nucleation layers (NL), GaN films of sufficient quality have been produced for blue LEDs. However, for laser and large-area microwave device applications, the large number of dislocations (> 108 cm−2) limit device performance, and techniques are desired to reduce dislocation density during the growth process. Here, we demonstrate how low temperature AlN interlayers (IL) sandwiched between high temperature (HT) GaN layers can be used to improve the electrical, optical, and structural properties of Si doped GaN films. A nearly two-fold increase in mobility is observed in Si doped GaN grown using 5 AlN IL compared to GaN grown on a single AlN NL. For GaN films grown on multiple AlN IL, cross-sectional transmission electron microscopy images reveal a significant reduction in the screw dislocation density and photoluminescence spectra reveal a reduction in yellow band intensity. An analysis of the electrical data based on a single donor/single acceptor model suggests that the improved electron mobility is the result of a reduced acceptor concentration in the top GaN film. The reduction in the calculated acceptor concentration may be associated with the reduction of the screw dislocation density.

scholarly journals Quantitative Analysis of the Recovery Process in Pure Iron Using X-ray Diffraction Line Profile Analysis

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 895
Author(s):  
Shota Sugiyama ◽  
Toshio Ogawa ◽  
Lei He ◽  
Zhilei Wang ◽  
Yoshitaka Adachi
Keyword(s):  
Quantitative Analysis ◽  
Dislocation Density ◽  
Screw Dislocation ◽  
Edge Dislocation ◽  
Pure Iron ◽  
Annealing Temperature ◽  
Dislocation Core ◽  
Recovery Process ◽  
Line Profile Analysis ◽  
Screw Dislocation Density

We conducted quantitative analysis of the recovery process during pure iron annealing using the modified Williamson-Hall and Warren-Averbach methods. We prepared four types of specimens with different dislocation substructures. By increasing the annealing temperature, we confirmed a decrease in dislocation density. In particular, screw-dislocation density substantially decreased in the early stage of the recovery process, while edge-dislocation density gradually decreased as annealing temperature increased. Moreover, changes in hardness during the recovery process mainly depended on edge-dislocation density. Increases in annealing temperature weakly affected the dislocation arrangement parameter and crystallite size. Recovery-process modeling demonstrated that the decrease in screw-dislocation density during the recovery process was mainly dominated by glide and/or cross-slip with dislocation core diffusion. In contrast, the decrease in edge-dislocation density during the recovery process was governed by a climbing motion with both dislocation core diffusion and lattice self-diffusion. From the above results, we succeeded in quantitatively distinguishing between edge- and screw-dislocation density during the recovery process, which are difficult to distinguish using transmission electron microscope and electron backscatter diffraction.

Correlation betweenJ c and screw dislocation density in sputtered YBa2Cu3O7-? films

1992 ◽  
Vol 86 (2) ◽  
pp. 177-181 ◽  
Author(s):  
J. Mannhart ◽  
D. Anselmetti ◽  
J. G. Bednorz ◽  
A. Catana ◽  
Ch. Gerber ◽  
...  
Keyword(s):  
Dislocation Density ◽  
Screw Dislocation ◽  
Screw Dislocation Density

Material and optical properties of GaAs grown on (001) Ge/Si pseudo-substrate

2004 ◽  
Vol 809 ◽  
Author(s):  
Yves Chriqui ◽  
Ludovic Largeau ◽  
Gilles Patriarche ◽  
Guillaume Saint-Girons ◽  
Sophie Bouchoule ◽  
...  
Keyword(s):  
Optical Properties ◽  
Dislocation Density ◽  
High Speed ◽  
Chemical Vapor ◽  
Atomic Layer ◽  
Lattice Parameter ◽  
Photoluminescence Intensity ◽  
High Quality ◽  
Light Emitting ◽  
Thermal Expansion Coefficients

ABSTRACTOne of the major challenges during recent years was to achieve the compatibility of III-V semiconductor epitaxy on silicon substrates to combine opto-electronics with high speed circuit technology. However, the growth of high quality epitaxial GaAs on Si is not straightforward due to the intrinsic differences in lattice parameters and thermal expansion coefficients of the two materials. Moreover, antiphase boundaries (APBs) appear that are disadvantageous for the fabrication of light emitting devices. Recently the successful fabrication of high quality germanium layers on exact (001) Si by chemical vapor deposition (CVD) was reported. Due to the germanium seed layer the lattice parameter is matched to the one of GaAs providing for excellent conditions for the subsequent GaAs growth. We have studied the material morphology of GaAs grown on Ge/Si PS using atomic layer epitaxy (ALE) at the interface between Ge and GaAs. We present results on the reduction of APBs and dislocation density on (001) Ge/Si PS when ALE is applied. The ALE allows the reduction of the residual dislocation density in the GaAs layers to 105 cm−2 (one order of magnitude as compared to the dislocation density of the Ge/Si PS). The optical properties are improved (ie. increased photoluminescence intensity). Using ALE, light emitting diodes based on strained InGaAs/GaAs quantum well as well as of In(Ga)As quantum dots on an exactly oriented (001) Ge/Si pseudo-substrate were fabricated and characterized.

The Effect of Dislocation Density and Surface Morphology on the Optical Properties of InGaN/GaN Quantum Wells Grown onr-Plane Sapphire Substrates

2011 ◽  
Vol 50 (8R) ◽  
pp. 080201
Author(s):  
Tom J. Badcock ◽  
Rui Hao ◽  
Michelle A. Moram ◽  
Menno J. Kappers ◽  
Phil Dawson ◽  
...  
Keyword(s):  
Optical Properties ◽  
Dislocation Density ◽  
Surface Morphology ◽  
Quantum Wells ◽  
Sapphire Substrates

Study of Dislocation Densities of Thick GaN Films

2014 ◽  
Vol 989-994 ◽  
pp. 387-390
Author(s):  
Yon Gan Li ◽  
Xiang Qian Xiu ◽  
Xue Mei Hua ◽  
Shi Ying Zhang ◽  
Shi Pu Gu ◽  
...  
Keyword(s):  
High Resolution ◽  
Dislocation Density ◽  
Screw Dislocation ◽  
Edge Dislocation ◽  
Thick Films ◽  
X Ray Diffraction ◽  
X Ray ◽  
Dislocation Densities ◽  
Edge Dislocations

The dislocation density of GaN thick films has been measured by high-resolution X-ray diffraction. The results show that both the edge dislocations and the screw dislocation reduce with increasing the GaN thickness. And the edge dislocations have a larger fraction of the total dislocation densities, and the densities for the edge dislocation with increasing thickness reduce less in contrast with those for the screw dislocation.

Sign in / Sign up

Export Citation Format

Share Document