Defect Microstructure of Thin Wurtzite GaN Films Grown by MBE

1995 ◽  
Vol 395 ◽  
Author(s):  
B.N. Sverdlov ◽  
A. Botchkarev ◽  
G.A. Martin ◽  
A. Salvador ◽  
H. MorkoÇ ◽  
...  
Keyword(s):  
Molecular Beam ◽  
Buffer Layers ◽  
Full Width ◽  
Cross Sectional ◽  
Rocking Curve ◽  
X Ray ◽  
Transmission Electron ◽  
Threading Defects ◽  
Defect Densities ◽  
Defect Microstructure

ABSTRACTThin films of wurtzite GaN have been grown by molecular beam epitaxy on 6H SiC (basal plane), Si {111} and sapphire (c-plane) substrates with and without various buffer layers. The defect microstructure of the films and the substrate/buffer/GaN interfacial quality have been characterized by cross-sectional transmission electron microscopy. The morphology was dominated by threading defects that originated at the substrate/buffer and/or buffer/film interfaces. Typical defect densities dropped rapidly with distance from the substrate but remained ∼108–109/cm2, depending on the particular substrate, for film thicknesses approaching one micron or more. The best quality films were grown at 770°C on sapphire with A1N buffer layers, and had X-ray rocking curve full-width at half-maximum values of ∼ 55arc-sec.

Spontaneous Lateral Modulations in InAlAs Buffer Layers Grown by MBE on InP Substrates

1995 ◽  
Vol 417 ◽  
Author(s):  
F. Peiró ◽  
A. Cornet ◽  
J. C. Ferrer ◽  
J. R. Morante ◽  
G. Halkias ◽  
...  
Keyword(s):  
Quantum Wells ◽  
Molecular Beam ◽  
Buffer Layers ◽  
Single Quantum ◽  
X Ray Diffraction ◽  
Single Quantum Well ◽  
Quantum Well Structures ◽  
X Ray ◽  
Transmission Electron ◽  
Inp Substrates

AbstractTransmission Electron Microscopy (TEM) and X-ray Diffraction (XRD) have been used to analyze the spontaneous appearance of lateral composition modulations in InyAl1−yAs (yIn.≅ 50%) buffer layers of single quantum well structures grown by molecular beam epitaxy on exact and vicinal (100) InP substrates, at growth temperatures in the range of 530°C–580°C. The influence of the growth temperature, substrate misorientation and epilayer mismatch on the InAlAs lateral modulation is discussed. The development of a self-induced quantum-wire like morphology in the In0.53Ga0.47As single quantum wells grown over the modulated buffers is also commented on.

scholarly journals Structural Property Study for GeSn Thin Films

Materials ◽  
2020 ◽  
Vol 13 (16) ◽  
pp. 3645
Author(s):  
Liyao Zhang ◽  
Yuxin Song ◽  
Nils von den Driesch ◽  
Zhenpu Zhang ◽  
Dan Buca ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
Transmission Electron Microscopy ◽  
Molecular Beam ◽  
Chemical Vapor ◽  
Threading Dislocations ◽  
X Ray Diffraction ◽  
Cross Sectional ◽  
X Ray ◽  
Transmission Electron

The structural properties of GeSn thin films with different Sn concentrations and thicknesses grown on Ge (001) by molecular beam epitaxy (MBE) and on Ge-buffered Si (001) wafers by chemical vapor deposition (CVD) were analyzed through high resolution X-ray diffraction and cross-sectional transmission electron microscopy. Two-dimensional reciprocal space maps around the asymmetric (224) reflection were collected by X-ray diffraction for both the whole structures and the GeSn epilayers. The broadenings of the features of the GeSn epilayers with different relaxations in the ω direction, along the ω-2θ direction and parallel to the surface were investigated. The dislocations were identified by transmission electron microscopy. Threading dislocations were found in MBE grown GeSn layers, but not in the CVD grown ones. The point defects and dislocations were two possible reasons for the poor optical properties in the GeSn alloys grown by MBE.

Optical properties of GaN with Ga and N polarity

2001 ◽  
Vol 693 ◽  
Author(s):  
M. A. Reshchikov ◽  
D. Huang ◽  
F. Yun ◽  
P. Visconti ◽  
T. King ◽  
...  
Keyword(s):  
Molecular Beam ◽  
Threading Dislocations ◽  
X Ray Diffraction ◽  
Cross Sectional ◽  
X Ray ◽  
Radiative Efficiency ◽  
Sapphire Substrates ◽  
Transmission Electron ◽  
And Inversion

AbstractWe compared photoluminescence (PL) and cross-sectional transmission electron microscopy (TEM) characteristics of GaN samples with Ga and N polarities grown by molecular beam epitaxy (MBE) on sapphire substrates. Ga-polar films grown at low temperature typically have very smooth surfaces, which are extremely difficult to etch with acids or bases. In contrast, the N-polar films have rougher surfaces and can be easily etched in hot H3PO4 or KOH. The quality of the X-ray diffraction spectra is also much better in case of Ga-polar films. Surprisingly, PL efficiency is always much higher in the N-polar GaN, yet the features and shape of the PL spectra are comparable for both polarities. We concluded that, despite the excellent quality of the surface, MBE-grown Ga-polar GaN layers contain higher concentration of nonradiative defects. From the analyses of cross-sectional TEM investigations, we have found that Ga-polar films have high density of threading dislocations (5x109 cm-2) and low density of inversion domains (1x107 cm-2). For N-polar GaN the situation is the reverse: the density of dislocations and inversion domains are 5x108 and ~1x1011 cm-2, respectively. One of the important conclusions derived from the combined PL and TEM study is that inversion domains do not seem to affect the radiative efficiency very adversly, whereas dislocations reduce it significantly.

Gallium Nitride Epitaxy on Silicon: Importance of Substrate Preparation

1995 ◽  
Vol 395 ◽  
Author(s):  
G. A. Martin ◽  
B. N. Sverdlov ◽  
A. Botchkarev ◽  
H. Morkoç ◽  
D. J. Smith ◽  
...  
Keyword(s):  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
Substrate Surface ◽  
Substrate Preparation ◽  
Rocking Curve ◽  
X Ray ◽  
Surface Steps ◽  
Threading Defects ◽  
Atomically Flat

ABSTRACTHexagonal GaN films grown on non-isomorphic substrates are usually characterized by numerous threading defects which are essentially boundaries between wurtzite GaN domains where the stacking sequences do not align. One origin of these defects is irregularities on the substrate surface such as surface steps. Using Si <111> substrates and a substrate preparation procedure that makes wide atomically flat terraces, we demonstrate that reduction of these irregularities greatly improves the crystalline and luminescent quality of GaN films grown by plasma-enhanced molecular beam epitaxy. X-ray rocking curve width decreases from over 1 degree to less than 20 minutes, while PL halfwidth decreases from over 15 meV to less than 10 meV.

Insertion effect of the 3-nm-thick Co(Pt) layer on AlN preferred orientation and residual stress in the c-axis textured AlN film

2013 ◽  
Vol 1515 ◽  
Author(s):  
Takashi Harumoto ◽  
Shinji Muraishi ◽  
Ji Shi ◽  
Yoshio Nakamura ◽  
Takashi Ishiguro
Keyword(s):  
Residual Stress ◽  
Preferred Orientation ◽  
Two Dimensional ◽  
Full Width ◽  
Sensitive Detector ◽  
Rocking Curve ◽  
X Ray ◽  
Transmission Electron ◽  
Aln Film ◽  
Sputter Deposited

ABSTRACTThe effect of the continuously inserted 3-nm-thick Co(Pt) layer on the preferred orientation of AlN film is investigated, and highly c-axis textured AlN film has been obtained. According to high resolution transmission electron microscope observations, the preferred orientation of sputter-deposited AlN film is improved from polycrystalline to (001) texture at the interface between AlN and Co(Pt)(111). The texture of AlN films are also examined using an x-ray diffractometer equipped with a two dimensional positive sensitive detector. The x-ray rocking curve full width at half maximum of 002AlN of (001) textured AlN with the Co(Pt) layer is 2.7°, and the residual stress of such specimen is 1.6 GPa in tensile stress.

MBE Growth of Ferroelectric YMnO3 Thin Films on Si(111) Using Y2O3 Buffer Layers

1998 ◽  
Vol 541 ◽  
Author(s):  
Shogo Imada ◽  
Shigeto Shouriki ◽  
Eisuke Tokumitsu ◽  
Hiroshi Ishiwara
Keyword(s):  
Thin Films ◽  
Molecular Beam ◽  
Ferroelectric Properties ◽  
High Energy ◽  
Buffer Layers ◽  
Mbe Growth ◽  
Rocking Curve ◽  
X Ray ◽  
Si Substrates

AbstractA ferroelectric YMnO3 thin films are grown on Si (111) substrates using Y2O3 buffer layers by molecular beam epitaxy (MBE). In-situ reflection high-energy electron diffraction (RHEED) analyses show that both Y2O3 and YMnO3 films are epitaxially grown on Si substrates. X-ray rocking curve measurements also show that the best FWHM (full width at half maximum) values for Y2O3 and YMnO3 films are 0.40° and 0.8°, respectively. C-V characteristics of Al/YMnO3/Y2O3/Si structures indicate the ferroelectric properties of YMnO3 films with a memory window of 0.7V.

scholarly journals Domain growth of Dy2O3 buffer layers on SrTiO3

1993 ◽  
Vol 8 (6) ◽  
pp. 1373-1378 ◽  
Author(s):  
A. Catana ◽  
J-P. Locquet
Keyword(s):  
Electron Microscopy ◽  
Molecular Beam ◽  
Substrate Surface ◽  
Crystallographic Analysis ◽  
Buffer Layers ◽  
Domain Growth ◽  
Structural Perfection ◽  
X Ray ◽  
Transmission Electron ◽  
Diffraction Patterns

Dy2O3 layers have been grown on SrTiO3 by molecular beam epitaxy. X-ray and electron diffraction patterns clearly show that Dy2O3 grows epitaxially on SrTiO3 with {100} planes parallel to the substrate surface. Transmission electron microscopy reveals that the Dy2O3 film breaks up into small domains (10–40 nm). This leads to the formation of terraces which limits the structural perfection of thin overgrown DyBa2Cu3O7 by introducing steps and small misorientations (within 3°). The resulting surface corrugation does not preclude the growth of epitaxial c-axis DyBa2Cu3O7 films with a Tc0 of 86 K. Crystallographic analysis and image calculations show that the domain growth of Dy2O3 is associated with the formation of 90° rotation twins.

Ultraviolet photon-induced heteroepitaxy of CdTe on GaAs

1988 ◽  
Vol 3 (6) ◽  
pp. 1144-1150 ◽  
Author(s):  
N. W. Cody ◽  
U. Sudarsan ◽  
R. Solanki
Keyword(s):  
Full Width ◽  
Half Maximum ◽  
Double Crystal ◽  
Rocking Curve ◽  
X Ray ◽  
Gaas Substrates ◽  
Deposition Parameters ◽  
Transmission Electron ◽  
Cdte Films ◽  
The Relationship

Ultraviolet photon-induced metalorganic vapor phase epitaxy of CdTe films on GaAs substrates has been investigated using diethyltelluride and dimethylcadmium as the precursor gases. The relationship between the deposition parameters and the properties of the epilayers have been examined using transmission electron microscopy and x-ray rocking curves. Epilayers grown at 6μm/h show an x-ray double-crystal rocking curve full width at half-maximum (FWHM) of 250 arcsec.

Lattice Relaxation of AlN Buffer on Surface-Treated SiC in Molecular-Beam Epitaxy for Growth of High-Quality GaN

2002 ◽  
Vol 743 ◽  
Author(s):  
Jun Suda ◽  
Kouhei Miura ◽  
Misako Honaga ◽  
Norio Onojima ◽  
Yusuke Nishi ◽  
...  
Keyword(s):  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
Lattice Relaxation ◽  
Buffer Layers ◽  
Rocking Curve ◽  
X Ray ◽  
Hcl Gas ◽  
Aln Buffer ◽  
Atomically Flat

ABSTRACTThe effects of SiC surface treatment on the lattice relaxation of AlN buffer layers and the crystalline quality of GaN layers grown on the buffer layers were studied. AlN buffer layers and GaN main layers were grown by plasma-assisted molecular-beam epitaxy on on-axis 6H-SiC (0001)Si substrates. High-temperature HCl-gas etching resulted in an atomically flat SiC surface with (√3×√3)R30° surface reconstruction, while HCl-gas etching followed by HF chemical treatment resulted in an atomically flat surface with (1×1) structure. The AlN layer grown on the (1×1) surface showed slower lattice relaxation. GaN grown on the AlN buffer layer exhibited a (0002) X-ray rocking curve of 70 arcsec and 107 cm−2 of screw-type dislocation density, which was superior than that of GaN grown on (√3×√3)R30° surface.

Manifestation of structural defects in photoluminescence from GaN

2003 ◽  
Vol 798 ◽  
Author(s):  
M. A. Reshchikov ◽  
J. Jasinski ◽  
F. Yun ◽  
L. He ◽  
Z. Liliental-Weber ◽  
...  
Keyword(s):  
Point Defects ◽  
Molecular Beam ◽  
Stacking Faults ◽  
Structural Defects ◽  
Large Set ◽  
X Ray Diffraction ◽  
Cross Sectional ◽  
X Ray ◽  
Transmission Electron ◽  
Gan Crystal

ABSTRACTSharp peaks of unidentified nature are detected in the low-temperature photoluminescence (PL) spectrum of undoped GaN in the photon energy range between 3.0 and 3.46 eV. These PL lines are commonly attributed to excitons bound to yet unidentified structural defects. We analyzed X-ray diffraction data in a large set of GaN samples grown by molecular beam epitaxy in order to find any correlation between these unusual PL peaks and the GaN crystal structure. Moreover, in selected samples exhibiting such peaks, cross-sectional transmission electron microscopy was taken in an effort to detect the presence and density of various structural defects. The preliminarily results indicate that most of unusual PL lines in GaN (Y lines) are not directly related to the observed structural defects, such as edge, screw, mixed dislocations, or stacking faults. However, there exists the possibility that point defects trapped at dislocations or other structural defects are responsible for these PL lines.

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