scholarly journals Enhanced Properties of Extended Wavelength InGaAs on Compositionally Undulating Step-Graded InAsP Buffers Grown by Molecular Beam Epitaxy

Crystals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1590
Author(s):  
Xuefei Li ◽  
Jianming Xu ◽  
Tieshi Wei ◽  
Wenxian Yang ◽  
Shan Jin ◽  
...  
Keyword(s):  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
Empirical Equation ◽  
Localized States ◽  
Threading Dislocation ◽  
Ingaas Layer ◽  
Peak Energy ◽  
Strain Compensation ◽  
Full Relaxation ◽  
Good Agreement

The extended wavelength InGaAs material (2.3 μm) was prepared by introducing compositionally undulating step-graded InAsyP1−y buffers with unequal layer thickness grown by solid-source molecular beam epitaxy (MBE). The properties of the extended wavelength InGaAs layer were investigated. The surface showed ordered crosshatch morphology and a low roughness of 1.38 nm. Full relaxation, steep interface and less than one threading dislocation in the InGaAs layer were demonstrated by taking advantage of the strain compensation mechanism. Room temperature photoluminescence (PL) exhibited remarkable intensity attributed to the lower density of deep non-radiative centers. The emission peak energy with varied temperatures was in good agreement with Varshni’s empirical equation, implying high crystal quality without inhomogeneity-induced localized states. Therefore, our work shows that compositionally undulating step-graded InAsP buffers with a thinner bottom modulation layer, grown by molecular beam epitaxy, is an effective approach to prepare InGaAs materials with wavelengths longer than 2.0 μm and to break the lattice limitation on the materials with even larger mismatch.

Optical and structural prorerties of InAs epilayer on graded InGaAs

2001 ◽  
Vol 696 ◽  
Author(s):  
Gu Hyun Kim ◽  
Jung Bum Choi ◽  
Joo In Lee ◽  
Se-Kyung Kang ◽  
Seung Il Ban ◽  
...  
Keyword(s):  
Molecular Beam Epitaxy ◽  
Residual Strain ◽  
Molecular Beam ◽  
Lattice Mismatch ◽  
Peak Position ◽  
Excitation Intensity ◽  
Total Thickness ◽  
Ingaas Layer ◽  
X Ray Diffraction ◽  
X Ray

AbstractWe have studied infrared photoluminescence (PL) and x-ray diffraction (XRD) of 400 nm and 1500 nm thick InAs epilayers on GaAs, and 4 nm thick InAs on graded InGaAs layer with total thickness of 300 nm grown by molecular beam epitaxy. The PL peak positions of 400 nm, 1500 nm and 4 nm InAs epilayer measured at 10 K are blue-shifted from that of InAs bulk by 6.5, 4.5, and 6 meV, respectively, which can be largely explained by the residual strain in the epilayer. The residual strain caused by the lattice mismatch between InAs and GaAs or graded InGaAs/GaAs was observed from XRD measurements. While the PL peak position of 400 nm thick InAs layer is linearly shifted toward higher energy with increase in excitation intensity ranging from 10 to 140 mW, those of 4 nm InAs epilayer on InGaAs and 1500 nm InAs layer on GaAs is gradually blue-shifted and then, saturated above a power of 75 mW. These results suggest that adopting a graded InGaAs layer between InAs and GaAs can efficiently reduce the strain due to lattice mismatch in the structure of InAs/GaAs.

Reduced threading dislocation densities in high-T/N-rich grown InN films by plasma-assisted molecular beam epitaxy

2013 ◽  
Vol 102 (5) ◽  
pp. 051916 ◽  
Author(s):  
Bernhard Loitsch ◽  
Fabian Schuster ◽  
Martin Stutzmann ◽  
Gregor Koblmüller
Keyword(s):  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
Threading Dislocation ◽  
Dislocation Densities

Stacked Layers of C-Induced Ge Quantum Dots

1998 ◽  
Vol 533 ◽  
Author(s):  
O. G. Schmidt ◽  
K. Eberl ◽  
S. Schieker ◽  
N. Y. Jin-Phillipp ◽  
F. Phillipp ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
Optoelectronic Devices ◽  
Vertical Alignment ◽  
Strain Fields ◽  
Identical Structure ◽  
Strain Compensation ◽  
Ge Quantum Dots

AbstractFifty layers of carbon-induced germanium dots, separated by 9.6 nm Si, are stacked by solid source molecular beam epitaxy. Each dot layer consists of 0.2 monolayers of pre-deposited carbon and 2.4 monolayers of post-grown Ge. These carbon-induced germanium dots are only 10 to 15 nm in diameter and 1 to 2 nm in height. Vertical alignment due to penetrating strain fields of underlying dot layers is not observed. Unlike to an identical structure without the pre-growth of carbon, a variety of advantageous aspects such as strain compensation, strongly enhanced no-phonon photoluminescence at a wavelength of around 1.3 μm and the possibility of effective waveguiding make this stack of C-induced Ge islands an attractive structure for Si based optoelectronic devices.

InAs/GaAs quantum dot lasers with GaP strain-compensation layers grown by molecular beam epitaxy

2016 ◽  
Vol 213 (4) ◽  
pp. 958-964 ◽  
Author(s):  
Takeo Kageyama ◽  
Katsuyuki Watanabe ◽  
Quoc Huy Vo ◽  
Keizo Takemasa ◽  
Mitsuru Sugawara ◽  
...  
Keyword(s):  
Molecular Beam Epitaxy ◽  
Quantum Dot ◽  
Molecular Beam ◽  
Quantum Dot Lasers ◽  
Strain Compensation ◽  
Gaas Quantum Dot

Studies Of Photoreflectance in Cd1−x MnxTe/Cd1−yMnyTe Superlattices

1999 ◽  
Vol 588 ◽  
Author(s):  
Chenjia Chen ◽  
Xuezhong Wang ◽  
Haitao Li ◽  
Xiaogan Liang ◽  
Guangyu Chai ◽  
...  
Keyword(s):  
Molecular Beam Epitaxy ◽  
Quantum Confinement ◽  
Molecular Beam ◽  
Envelope Function ◽  
Exciton Transition ◽  
Transition Energies ◽  
Gaas Substrates ◽  
Quantum Confinement Effects ◽  
Measurement Results ◽  
Good Agreement

AbstractPhotoreflectance spectroscopy has been peformed on a series of Cd1−xMnxTe/Cd1−yMnyTe superlattices. Samples were grown on (001) GaAs substrates by molecular-beam epitaxy with different barriers (x=0.3 to 0.8) and wells (y=0 to 0.01). After taking into consideration the strain-induced and quantum confinement effects, the exciton transition energies of the heavy and light holes can be determined using envelope-function calculations. The calculations are in good agreement with the photoreflectance measurement results. These results show that photoreflectance is a powerful probe for the study of quantized state structures in superlattices.

High carrier concentrations of n- and p-doped GaN on Si(111) by nitrogen plasma-assisted molecular-beam epitaxy

2007 ◽  
Vol 22 (9) ◽  
pp. 2623-2630 ◽  
Author(s):  
L.S. Chuah ◽  
Z. Hassan ◽  
S.S. Ng ◽  
H. Abu Hassan
Keyword(s):  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
Hole Concentration ◽  
Nitrogen Plasma ◽  
Infrared Analysis ◽  
Hall Measurements ◽  
Band Emission ◽  
Gan On Si ◽  
Gan Crystal ◽  
Good Agreement

High-quality doped GaN layers were grown on silicon substrates by radio frequency nitrogen plasma-assisted molecular-beam epitaxy. High-temperature-grown AlN (about 200 nm) was used as a buffer layer. In-growth doping was done using high-purity Si and Mg as n- and p-type dopants, respectively. X-ray diffraction revealed that monocrystalline GaN was obtained. This is in good agreement with the results of morphological study by atomic force microscopy. Micro-photoluminescence (PL) and micro-Raman spectroscopy were used to study the room-temperature optical properties of the doping films. No yellow-band emission was observed in the PL spectroscopy. From the Hall measurements, the resulting n-type doping concentration was measured to be (1–2) × 1019 cm−3. Fairly uniform hole concentration as high as (4–5) × 1020 cm−3 throughout the GaN crystal was achieved. In terms of the carrier concentration, it was found that the results determined from the Fourier transform infrared analysis are in good agreement with the results determined from the Hall measurements.

Defects and localized states in MBE-grown GaAs1−xNxsolid solutions prepared by molecular-beam epitaxy

2003 ◽  
Vol 83 (21) ◽  
pp. 2531-2544 ◽  
Author(s):  
A. Y. Polyakov ◽  
N. B. Smirnov ◽  
A. V. Govorkov ◽  
V. T. Bublik ◽  
A. E. Botchkarev ◽  
...  
Keyword(s):  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
Localized States

scholarly journals Снижение плотности прорастающих дислокаций в темплейтах AlN/c-сапфир, выращенных методом плазменно-активированной молекулярно-пучковой эпитаксии

2020 ◽  
Vol 46 (8) ◽  
pp. 36
Author(s):  
В.В. Ратников ◽  
Д.В. Нечаев ◽  
А.В. Мясоедов ◽  
О.А. Кошелев ◽  
В.Н. Жмерик
Keyword(s):  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
Flux Ratio ◽  
Buffer Layers ◽  
Stress Generation ◽  
Threading Dislocation ◽  
X Ray Diffraction ◽  
X Ray ◽  
Temperature Regimes ◽  
Dislocation Densities

Multiple-crystal X-ray diffraction and a multi-beam optical stress sensor were used to study AlN/c-sapphire templates grown by plasma-assisted molecular beam epitaxy. The influence of the nucleation and buffer layers growth regimes, temperature, the ratio between Al and N* growth fluxes on the stress generation and the character of the dislocation structure were analyzed. Templates with the best crystal quality with screw and edge threading dislocation densities in a range of 4∙10^8 and 8∙10^9 cm-2, respectively, were obtained at the flux ratio of Al to N* close to 1 by using two-stage temperature regimes.

Shape and Size Distribution of Molecular Beam Epitaxy Grown Self-Assembled Ge Islands on Si (001) Substrates

2008 ◽  
Vol 8 (8) ◽  
pp. 4101-4105
Author(s):  
R. K. Singha ◽  
S. Das ◽  
K. Das ◽  
S. Majumdar ◽  
A. Dhar ◽  
...  
Keyword(s):  
Molecular Beam Epitaxy ◽  
Size Distribution ◽  
Molecular Beam ◽  
Alloy Composition ◽  
Strain Relaxation ◽  
X Ray ◽  
Compositional Changes ◽  
Annealing Experiments ◽  
Shape And Size ◽  
Good Agreement

We have performed a series of annealing experiments with Ge islands on Si (001) grown by molecular beam epitaxy, in order to clarify issues related to island stability and coarsening. The shape and size distribution of nanoislands as a function of annealing time at a temperature of 650 °C have been studied. Optical phonons from Raman spectra have been used as efficient probes to study the evolution of Si1−xGex islands. Both the alloy composition and residual strain in the islands have been determined from the phonon frequencies and Raman intensities. The experimental results are in good agreement with the strain relaxation estimated using X-ray rocking curves. The results indicate that the shape and size distribution of Ge islands are controlled via structural and compositional changes through strain relaxation by the periodic creation and extinction of tiny nanocrystals.

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