Annihilation of Threading Dislocations in Regrown GaN on Electrochemically Etched Nanoporous GaN Template with Optimization of Buffer Layer Growth

2007 ◽  
Vol 31 ◽  
pp. 227-229
Author(s):  
C.B. Soh ◽  
H. Hartono ◽  
S.Y. Chow ◽  
Soo Jin Chua
Keyword(s):  
Electron Microscopy ◽  
Buffer Layer ◽  
Electrochemical Etching ◽  
Layer Growth ◽  
Device Fabrication ◽  
Buffer Layers ◽  
Threading Dislocations ◽  
High Quality ◽  
Transmission Electron ◽  
Gan Buffer Layer

Nanoporous GaN template has been fabricated by electrochemical etching to give hexagonal pits with nano-scale pores of size 20-50 nm in the underlying grains. Electrochemical etching at The effect of GaN buffer layer grown at various temperatures from 650°C to 1015°C on these as-fabricated nano-pores templates are investigated by transmission electron microscopy. The buffer layer grown at the optimized temperature of 850°C partially fill up the pores and voids with annihilation of threading dislocations, serving as an excellent template for high-quality GaN growth. This phenomenon is, however not observed for the samples grown with other temperature buffer layers. The PL spectrum for the regrowth GaN on nanoporous GaN template also shows an enhancement of PL intensity for GaN peak compared to as-grown GaN template, which is indicative of its higher crystal quality. This makes it as a suitable template for subsequent device fabrication.

scholarly journals Structural and optical properties of GaN laterally overgrown on Si(111) by metalorganic chemical vapor deposition using an AlN buffer layer

1999 ◽  
Vol 4 (1) ◽  
Author(s):  
H. Marchand ◽  
N. Zhang ◽  
L. Zhao ◽  
Y. Golan ◽  
S.J. Rosner ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Buffer Layer ◽  
Chemical Vapor ◽  
Silicon Substrates ◽  
Seed Region ◽  
Threading Dislocations ◽  
Transmission Electron ◽  
Aln Buffer ◽  
Image Position ◽  
Cathodoluminescence Imaging

Lateral epitaxial overgrowth (LEO) on Si(111) substrates using an AlN buffer layer is demonstrated and characterized using scanning electron microscopy, atomic force microscopy, transmission electron microscopy, x-ray diffraction, photoluminescence spectroscopy, and cathodoluminescence imaging. The <100>-oriented LEO GaN stripes grown on silicon substrates are shown to have similar structural properties as LEO GaN grown on GaN/Al2O3 substrates: the surface topography is characterized by continuous crystallographic steps rather than by steps terminated by screw-component threading dislocations; the density of threading dislocations is <106 cm−2; the LEO regions exhibit crystallographic tilt (0.7-4.7°) relative to the seed region. The AlN buffer thickness affects the stripe morphology and, in turn, the microstructure of the LEO GaN. The issues of chemical compability and thermal expansion mismatch are discussed.

Atomic Force Microscopy Study of GaN-Buffer Layers on SiC(0001) By MOCVD

1996 ◽  
Vol 423 ◽  
Author(s):  
Dongsup Lim ◽  
Dongjin Byun ◽  
Gyeungho Kim ◽  
Ok-Hyun Nam ◽  
In-Hoon Choi ◽  
...  
Keyword(s):  
Buffer Layer ◽  
Microscopy Study ◽  
Growth Conditions ◽  
Interfacial Free Energy ◽  
Buffer Layers ◽  
Optimum Growth ◽  
Cross Sectional ◽  
Atomic Force ◽  
Transmission Electron ◽  
Gan Buffer Layer

AbstractBuffer layers promote lateral growth of films due to a decrease in interfacial free energy between the film and substrate, and large 2-dimensional nucleation. Smooth surfaces of thebuffer layers are desired. Optimum conditions for GaN-buffer growth on the vicinal surface of 6H-SiC(0001) were determined by atomic force microscope (AFM). AFM analysis of the GaN nucleation layers led to an optimum growth conditions of the GaN-buffer layer which was confirmed by cross-sectional transmission electron microscopy, Hall measurements and photoluminescence spectra. Optimum growth conditions for GaN-buffer layer on SiC(0001) was determined to be 1 minute growing at 550°C.

Growth and properties of epitaxial PbSe on Si(111) and Si(100) without buffer layer

1995 ◽  
Vol 379 ◽  
Author(s):  
P. Müller ◽  
A.N. Tiwari ◽  
H. Zogg
Keyword(s):  
Buffer Layer ◽  
Lattice Mismatch ◽  
Infrared Detector ◽  
Device Fabrication ◽  
Buffer Layers ◽  
Silicon Substrates ◽  
High Quality ◽  
Si Substrates ◽  
Large Lattice ◽  
Large Lattice Mismatch

Narrow gap IV-VI materials like PbS, PbSnSe and PbSnTe are used for infrared detector device fabrication [1,2]. Earlier an intermediate Ila-fluoride buffer layer, which consisted of a BaF2/CaF2-stack of about 2000 Å thickness, was used to get epitaxial high quality layers on silicon substrates. This buffer is now reduced to a much thinner layer of only about 20 Å thick CaF2, regardless the large lattice mismatch between layer and substrate [3,4,5]. The question therefore arises if high quality IV-VI layers can be grown on Si-substrates without any buffer layer as e.g. in CdTe/Si or GaAs/Si systems.The aim of this work is to grow IV-VI layers directly on Si-substrates without any buffer layers to study the growth kinetics and epitaxial quality. PbSe was chosen as a representant of IV-VI materials, and layers were grown on (111)- and (100)-oriented silicon substrates.

scholarly journals High Quality GaAs Epilayers Grown on Si Substrate Using 100 nm Ge Buffer Layer

2016 ◽  
Vol 2016 ◽  
pp. 1-5 ◽  
Author(s):  
Wei-Cheng Kuo ◽  
Hung-Chi Hsieh ◽  
Wu Chih-Hung ◽  
Huang Wen-Hsiang ◽  
Chien-Chieh Lee ◽  
...  
Keyword(s):  
Buffer Layer ◽  
High Efficiency ◽  
Electron Cyclotron Resonance ◽  
Low Cost ◽  
Chemical Vapor ◽  
Buffer Layers ◽  
High Quality ◽  
Tandem Solar Cells ◽  
Hydrogen Flow ◽  
Transmission Electron

We present high quality GaAs epilayers that grow on virtual substrate with 100 nm Ge buffer layers. The thin Ge buffer layers were modulated by hydrogen flow rate from 60 to 90 sccm to improve crystal quality by electron cyclotron resonance chemical vapor deposition (ECR-CVD) at low growth temperature (180°C). The GaAs and Ge epilayers quality was verified by X-ray diffraction (XRD) and spectroscopy ellipsometry (SE). The full width at half maximum (FWHM) of the Ge and GaAs epilayers in XRD is 406 arcsec and 220 arcsec, respectively. In addition, the GaAs/Ge/Si interface is observed by transmission electron microscopy (TEM) to demonstrate the epitaxial growth. The defects at GaAs/Ge interface are localized within a few nanometers. It is clearly showed that the dislocation is well suppressed. The quality of the Ge buffer layer is the key of III–V/Si tandem cell. Therefore, the high quality GaAs epilayers that grow on virtual substrate with 100 nm Ge buffer layers is suitable to develop the low cost and high efficiency III–V/Si tandem solar cells.

Role of Si1−xGex Buffer Layer in Determining Electrical Characteristics of Modulation-Doped p-Si0. 5Ge0.5/Ge/Si1−xGex Heterostructures

1990 ◽  
Vol 198 ◽  
Author(s):  
Eiichi Murakami ◽  
Hiroyuki Etoh ◽  
Akio Nishida ◽  
Kiyokazu Nakagawa ◽  
Masanobu Miyao
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Raman Spectroscopy ◽  
Buffer Layer ◽  
Hole Mobility ◽  
Threading Dislocations ◽  
Electrical Characteristics ◽  
Transmission Electron

ABSTRACTElectrical characteristics of modulation-doped p-Si0.5Ge0.5/Ge/Si1−x Gex heterostructures are examined in relation to Si fraction (1−X) and thickness (dB)of the buffer layer (Si1−xGex), using Raman spectroscopy and transmission electron microscopy. Strain-induced enhancement of hole mobility and concentration is observed in 1-X≦0.25. However, their decrease in 1-X≦0.25 and for small dB values is also observed, which is attributed to the increase in threading dislocations. As a result, a maximum hole mobility of 7600 cm2/Vs at 77 K is obtained at 1-X=0.25 and dB=1μm.

A Study of the Effect of Growth Rate and Annealing on GaN Buffer Layers on Sapphire

1995 ◽  
Vol 395 ◽  
Author(s):  
J.C. Ramer ◽  
K. Zheng ◽  
C.F. Kranenberg ◽  
M. Banas ◽  
S.D Hersee
Keyword(s):  
Growth Rate ◽  
Buffer Layer ◽  
Layer Growth ◽  
Buffer Layers ◽  
Degree Of Crystallinity ◽  
X Ray Diffraction ◽  
X Ray ◽  
Force Microscopy ◽  
Atomic Force ◽  
Gan Buffer Layer

ABSTRACTUsing atomic force microscopy (AFM) and X-ray diffraction (XRD) we have determined that on [0001] oriented sapphire, the GaN buffer layer shows a degree of crystallinity that is dependent on growth rate. Annealing studies show evolution of the crystallinity and the emergence of a preferred orientation. Also, substrate orientation is found to influence the buffer layer crystallinity. Based on this work and previous results, we propose that the GaN buffer layer growth can be described by the Stranski-Krastanov growth process.

scholarly journals Асимметрия дефектной структуры полуполярного GaN, выращенного на Si(001)

2018 ◽  
Vol 44 (20) ◽  
pp. 53
Author(s):  
А.Е. Калмыков ◽  
А.В. Мясоедов ◽  
Л.М. Сорокин
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Gallium Nitride ◽  
Epitaxial Layer ◽  
Vapor Phase ◽  
Defect Structure ◽  
Vapor Phase Epitaxy ◽  
Buffer Layers ◽  
Threading Dislocations ◽  
Transmission Electron

AbstractThe defect structure of a thick (~15 μm) semipolar gallium nitride (GaN) layer grown by hydride–chloride vapor phase epitaxy on a Si(001) substrate with buffer layers has been studied by transmission electron microscopy. The asymmetry of the defect structure of GaN epilayer has been revealed and analyzed. The influence of this asymmetry on the rate of decrease in the density of threading dislocations in the growing epitaxial layer is discussed.

Transmission electron microscopy study of epitaxial InN thin films grown on c-plane sapphire

2006 ◽  
Vol 21 (7) ◽  
pp. 1693-1699 ◽  
Author(s):  
C.J. Lu ◽  
X.F. Duan ◽  
Hai Lu ◽  
William J. Schaff
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
Transmission Electron Microscopy ◽  
Film Growth ◽  
Microscopy Study ◽  
Electron Microscopy Study ◽  
Threading Dislocations ◽  
Transmission Electron Microscopy Study ◽  
Transmission Electron ◽  
Gan Buffer Layer

High-quality epitaxial InN thin films grown on (0001) sapphire with GaN buffer were characterized using transmission electron microscopy. It was found that the GaN buffer layer exhibits the (0001) Ga polarity and the InN film has In-terminated polarity. At the InN/GaN interface, there exists a high density of misfit dislocation (MD) array. Perfect edge threading dislocations (TDs) with (1/3)〈1120〉 Burgers vectors are predominant defects that penetrate the GaN and InN layers. Pure screw and mixed TDs were also observed. Overall, the TD density decreases during film growth due to annihilation and fusion. The TD density in GaN is as high as ∼1.5 × 1011 cm−2, and it drops rapidly to ∼2.2 × 1010 cm−2 in InN films. Most half-loops in GaN are connected with MD segments at the InN/GaN interface to form loops, while some TD segments threaded the interface. Half-loops were also generated during the initial stages of InN growth.

Effect of Si Doping on The Structure of Gan

1996 ◽  
Vol 423 ◽  
Author(s):  
Zuzanna Liliental-Weber ◽  
S. Ruvimov ◽  
T. Suski ◽  
J. W. Ager ◽  
W. Swider ◽  
...  
Keyword(s):  
Buffer Layer ◽  
Dopant Concentration ◽  
Buffer Layers ◽  
Threading Dislocation ◽  
Threading Dislocations ◽  
Silicon Doping ◽  
Defect Reduction ◽  
Si Doping ◽  
Transmission Electron ◽  
Metal Organic

AbstractThe influence of Si doping on the structure of GaN grown by metal-organic chemicalvapor deposition (MOCVD) has been studied using transmission electron microscopy (TEM), x-ray diffraction and Raman spectroscopy. Undoped and low Si doped samples were compared with samples of increased dopant concentration. In addition, defect reduction due to different buffer layers (AIN and GaN) is discussed. Silicon doping improves surface morphology and influences threading dislocation arrangement. High doping leads to a more random distribution of dislocations. Based on this study it appears (for the same dopant concentration) that an AIN buffer layer can significantly reduce the number of threading dislocations, leaving the samples more strained. However, no significant reduction of threading dislocations could be observed in the samples with GaN buffer layer. These samples are the least strained.

Strain in Epitaxial GaAs on Si and CaF2/Si

1987 ◽  
Vol 102 ◽  
Author(s):  
L. J. Schowalter ◽  
Shin Hashimoto ◽  
G. A. Smith ◽  
W. M. Gibson ◽  
N. Lewis ◽  
...  
Keyword(s):  
Buffer Layer ◽  
Gaas Layer ◽  
Buffer Layers ◽  
Threading Dislocations ◽  
Si Substrate ◽  
High Quality ◽  
Strain Measurements ◽  
Epitaxial Gaas ◽  
Ion Channeling ◽  
Gaas On Si

ABSTRACTIn this paper, ion channeling techniques are used to show that epitaxial GaAs layers grown on vicinal Si(001) wafers do not have their [001] axis precisely aligned with that of the Si substrate. Instead, the [001] axis of the GaAs layer is found to be tilted toward the surface normal of the Si substrate. This tilt was found to be ∼0.2° on vicinal Si(001) substrates which have their [001] axis tilted 4° toward the [110] azimuth. It is speculated that this misalignment is reponsible for the residual density of threading dislocations in the GaAs on Si layer. An approach described here, which can be used to avoid strain in the GaAs layer, is to grow a CaF2 buffer layer between the Si substrate and the epitaxial GaAs layer. High quality epitaxial GaAs layers have been obtained on both CaF 2 /Si(001) and CaF 2 /Si(111) substrates. Strain measurements of the epitaxial GaAs on the CaF 2 buffer layers indicate that these layers have strains below our detection limits.

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