Defect engineering in AlGaN-based UV optoelectronic heterostructures grown on c-Al2O3 by plasma-assisted molecular beam epitaxy

2015 ◽  
Vol 1741 ◽  
Author(s):  
Sergei Rouvimov ◽  
Valentin N. Jmerik ◽  
Dmitrii V. Nechaev ◽  
Valentin V. Ratnikov ◽  
Alexey A. Toropov ◽  
...  
Keyword(s):  
Molecular Beam Epitaxy ◽  
Quantum Wells ◽  
Molecular Beam ◽  
Stimulated Emission ◽  
Defect Engineering ◽  
Transmission Electron ◽  
Migration Enhanced Epitaxy ◽  
Optimum Approach ◽  
Dislocations Density ◽  
Aln Buffer

ABSTRACTAlGaN-based SQW heterostructures grown by plasma-assisted molecular beam epitaxy on c-Al2O3 substrates have been studied with high resolution transmission electron microscopy (HR TEM), photoluminescence spectroscopy and x-ray diffraction. The high-temperature (780°C) synthesis of the AlN buffer layer nucleated on c-Al2O3 by a migration enhanced epitaxy and including several ultra-thin GaN interlayers grown under moderate N-rich conditions was shown to be the optimum approach for lowering the threading dislocations density down to 108-109 cm-2. HR TEM study has confirmed the fine structure of single quantum wells (SQW) formed by a sub-monolayer digital alloying technique and revealed different kinds of compositional inhomogeneities in the AlxGa1-xN barrier layers of the heterostructures, including the formation of Al-rich barriers induced by the temperature-modulated epitaxy and the spontaneous compositional disordering along the growth axis for x=0.6-0.7. The influence of these phenomena on the parameters of the mid-UV stimulated emission observed in the SQW structures has been studied as well.

Molecular Beam Epitaxy of Znl-x Cdx Se/ZnSe Heterostructures And Their Optical Properties

1991 ◽  
Vol 228 ◽  
Author(s):  
H. Luo ◽  
N. Samarth ◽  
J. K. Furdyna ◽  
H. Jeon ◽  
J. Ding ◽  
...  
Keyword(s):  
Optical Properties ◽  
Molecular Beam Epitaxy ◽  
Quantum Wells ◽  
Room Temperature ◽  
Molecular Beam ◽  
Stimulated Emission ◽  
Optically Pumped ◽  
Absorption Coefficients ◽  
Excitonic Absorption ◽  
Lasing Mechanism

ABSTRACTSuperlattices and quantum wells of Znl-xCdxSe/ZnSe, and heterostructures based on ZnSe/CdSe digital alloys have been grown by molecular beam epitaxy (MBE). Their optical properties were studied with particular emphasis on excitonic absorption and photopumped stimulated emission. Excitonic absorption is easily observable up to 400 K, and is characterized by extremely large absorption coefficients (α = 2×105cm−1). Optically pumped lasing action is obtained at room temperature with a typical threshold intensity of 100 kW/cm2. The lasing mechanism in these II-VI quantum wells appears to be quite different from that in the better studied III-V materials: in our case, the onset of stimulated emission occurs before the saturation of the excitonic absorption, and the stimulated emission occurs at an energy lower than that of the excitonic absorption.

scholarly journals Dopant-stimulated growth of GaN nanotube-like nanostructures on Si(111) by molecular beam epitaxy

2018 ◽  
Vol 9 ◽  
pp. 146-154 ◽  
Author(s):  
Alexey D Bolshakov ◽  
Alexey M Mozharov ◽  
Georgiy A Sapunov ◽  
Igor V Shtrom ◽  
Nickolay V Sibirev ◽  
...  
Keyword(s):  
Molecular Beam Epitaxy ◽  
Surface Density ◽  
Molecular Beam ◽  
Growth Parameters ◽  
Elongation Rate ◽  
The Novel ◽  
Geometrical Properties ◽  
Transmission Electron ◽  
Si Doped ◽  
Aln Buffer

In this paper we study growth of quasi-one-dimensional GaN nanowires (NWs) and nanotube (NT)-like nanostructures on Si(111) substrates covered with a thin AlN layer grown by means of plasma-assisted molecular beam epitaxy. In the first part of our study we investigate the influence of the growth parameters on the geometrical properties of the GaN NW arrays. First, we find that the annealing procedure carried out prior to deposition of the AlN buffer affects the elongation rate and the surface density of the wires. It has been experimentally demonstrated that the NW elongation rate and the surface density drastically depend on the substrate growth temperature, where 800 °C corresponds to the maximum elongation rate of the NWs. In the second part of the study, we introduce a new dopant-stimulated method for GaN nanotube-like nanostructure synthesis using a high-intensity Si flux. Transmission electron microscopy was used to investigate the morphological features of the GaN nanostructures. The synthesized structures have a hexagonal cross-section and possess high crystal quality. We propose a theoretical model of the novel nanostructure formation which includes the role of the dopant Si. Some of the Si-doped samples were studied with the photoluminescence (PL) technique. The analysis of the PL spectra shows that the highest value of donor concentration in the nanostructures exceeds 5∙1019 cm−3.

Generation and Suppression of Stacking Faults in Gap Layers Grown on Si(100) Substrates by Molecular Beam Epitaxy and Migration Enhanced Epitaxy

1996 ◽  
Vol 441 ◽  
Author(s):  
Y. Takagi ◽  
H. Yonezu ◽  
K. Samonji ◽  
T. Tsuji ◽  
N. Ohshima
Keyword(s):  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
Stacking Faults ◽  
Misfit Dislocations ◽  
Generation Process ◽  
Si Substrates ◽  
Transmission Electron ◽  
Migration Enhanced Epitaxy ◽  
Regular Network ◽  
And Migration

AbstractWe have investigated the generation process of crystalline defects in GaP layers grown on Si substrates (GaP/Si) by molecular beam epitaxy (MBE) and migration enhanced epitaxy (MEE). Transmission electron microscopy observations revealed that a regular network of misfit dislocations was generated in GaP/Si by MEE. On the other hand, threading dislocations as well as interfacial misfit dislocations were observed in GaP/Si by MBE. Moreover, stacking faults were generated in high density at the hetero-interface of GaP/Si by MBE. The density of stacking faults was drastically reduced by MEE.

scholarly journals Statistical Analysis of Local Composition and Luminescence in InGaN Grown by Molecular Beam Epitaxy

1999 ◽  
Vol 4 (S1) ◽  
pp. 263-268
Author(s):  
S. Einfeldt ◽  
T. Böttcher ◽  
D. Hommel ◽  
H. Selke ◽  
P. L. Ryder ◽  
...  
Keyword(s):  
Molecular Beam Epitaxy ◽  
Quantum Wells ◽  
Molecular Beam ◽  
Indium Content ◽  
Atomic Scale ◽  
Local Composition ◽  
Transmission Electron ◽  
Cathodoluminescence Spectroscopy ◽  
Short Period ◽  
Compositional Homogeneity

InGaN layers grown by molecular beam epitaxy are investigated in terms of their compositional homogeneity using transmission electron microscopy and cathodoluminescence spectroscopy performed with high spatial resolution. Strong fluctuations of the indium content were found in bulklike layers, which could be partially reduced by modulating the indium flux during growth, i. e. by nominally growing a short period GaN/InGaN superlattice. For indium compositions above x ≅ 0.1 this approach fails. Strained InGaN in quantum wells exhibits lateral fluctuations on an atomic scale and on a scale of several hundred nanometers. The results are discussed in view of the origin of inhomogeneous indium incorporation.

Statistical Analysis of Local Composition and Luminescence in InGaN Grown by Molecular Beam Epitaxy

1998 ◽  
Vol 537 ◽  
Author(s):  
S. Einfeldt ◽  
T. Böttcher ◽  
D. Hommel ◽  
H. Selke ◽  
P. L. Ryder ◽  
...  
Keyword(s):  
Molecular Beam Epitaxy ◽  
Quantum Wells ◽  
Molecular Beam ◽  
Indium Content ◽  
Atomic Scale ◽  
Local Composition ◽  
Transmission Electron ◽  
Cathodoluminescence Spectroscopy ◽  
Short Period ◽  
Compositional Homogeneity

AbstractInGaN layers grown by molecular beam epitaxy are investigated in terms of their compositional homogeneity using transmission electron microscopy and cathodoluminescence spectroscopy performed with high spatial resolution. Strong fluctuations of the indium content were found in bulk-like layers, which could be partially reduced by modulating the indium flux during growth, i. e. by nominally growing a short period GaN/InGaN superlattice. For indium compositions above x ≠ 0.1 this approach fails. Strained InGaN in quantum wells exhibits lateral fluctuations on an atomic scale and on a scale of several hundred nanometers. The results are discussed in view of the origin of inhomogeneous indium incorporation.

Preparation of InN and InN-Based Heterostructures by Molecular Beam Epitaxy

2001 ◽  
Vol 680 ◽  
Author(s):  
Hai Lu ◽  
William J. Schaff ◽  
Jeonghyun Hwang ◽  
Lester F. Eastman
Keyword(s):  
Molecular Beam Epitaxy ◽  
Carrier Concentration ◽  
Buffer Layer ◽  
Molecular Beam ◽  
Buffer Layers ◽  
X Ray Diffraction ◽  
Optimum Growth Temperature ◽  
Migration Enhanced Epitaxy ◽  
Dimensional Electron Gas ◽  
Aln Buffer

ABSTRACTInN is an important III-V compound semiconductor with many potential microelectronic and optoelectronic applications. In this study, we prepared epitaxial InN on (0001) sapphire with an AlN buffer layer by molecular beam epitaxy, and its variation, migration enhanced epitaxy. A series of samples were grown with different substrate temperatures ranging from 360°C to 590°C. The optimum growth temperature for InN was found to be between 450°C and 500°C. We also found that thicker AlN buffer layers result in the best InN quality. With increasing thickness of an AlN buffer layer, the Hall electron mobility of InN increases while the carrier concentration decreases. The surface morphology is also improved this way. Hall mobility greater than 800 cm2/Vs with carrier concentration 2-3×1018 cm−3 at room temperature can be routinely obtained for ∼0.1[.proportional]m thick InN films. Various InN-based heterostructures with AlInN or AlN barrier were fabricated. X-ray diffraction study clearly shows the barrier and InN layers. A 2-dimensional electron gas resulting from polarization induced electrons was observed in capacitance-voltage measurements. Some results on Mg doping of InN will be discussed as well.

Growth of 3C-(Si1-xC1-y)Gex+y Layers on 4H-SiC by Molecular Beam Epitaxy

2005 ◽  
Vol 483-485 ◽  
pp. 173-176 ◽  
Author(s):  
Petia Weih ◽  
Henry Romanus ◽  
Thomas Stauden ◽  
Lothar Spieß ◽  
Oliver Ambacher ◽  
...  
Keyword(s):  
Molecular Beam Epitaxy ◽  
Solid Solutions ◽  
Molecular Beam ◽  
Optimal Growth ◽  
Growth Conditions ◽  
Transmission Electron ◽  
Migration Enhanced Epitaxy ◽  
Different Temperatures ◽  
And Migration ◽  
Suitable Technique

In the present work cubic 3C-(Si1-xC1-y)Gex+y solid solutions were grown at different^temperatures by molecular beam epitaxy on on-axis 4H-SiC (0001) substrates. Two different growth methods are compared in order to explore the optimal growth conditions for the incorporation of Ge into the SiC lattice during the low temperature epitaxy. For this reason simultaneous growth and migration enhanced epitaxy were used. The chemical composition of the grown layers were analyzed by energy dispersive x-ray methods during transmission electron microscopy investigations. It was found that the migration enhanced epitaxy is a more suitable technique for the formation of high quality (Si1-xC1-y)Gex+y solid solutions. Additionally, polytypes transition from 4H-SiC to 3C-SiC occurs during the growth independent of the applied growth technique.

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