Transport in High-Mobility Si1−xGex Heterostructures Grown by Molecular-Beam Epitaxy

1992 ◽  
Vol 281 ◽  
Author(s):  
Don Monroe ◽  
Y.-H. Xie ◽  
E. A. Fitzgerald ◽  
P. J. Silverman
Keyword(s):  
Molecular Beam Epitaxy ◽  
Hall Effect ◽  
Molecular Beam ◽  
High Mobility ◽  
Interface Roughness ◽  
Buffer Layers ◽  
Threading Dislocation ◽  
Fractional Quantum Hall ◽  
Angle Scattering ◽  
Interface Roughness Scattering

ABSTRACTWe report Hall mobilities (at T = 4.2K) as high as 180,000cm2V−1 s−1 in modulation-doped Si layers in Si1−x Gex heterostructures grown by Molecular-Beam Epitaxy. These mobilities reflect dramatic improvements in the quality of relaxed Si1−xGex buffer layers (with x'30%) grown by gradual grading of composition at high temperature. The resulting moderate threading dislocation densities (< 106 cm−2 ) appear to cause no mobility degradation. The strong damping of Shubnikov de Haas oscillations, as well as the increase of mobility with carrier density, indicate predominantly small-angle scattering. This suggests that residual Coulomb scattering from background impurities limit the mobility, rather than interface-roughness scattering as for the Si/SiO2 interface. The reduced interfacial scattering, as well as the strain-induced splitting of the valley degeneracy to select the two low-effective-mass valleys, significantly enhance room-temperature transport as well, with μHall ' 2,100cm2 V−1 s−1. We also observe a small splitting of the remaining twofold valley degeneracy using the integral quantized Hall effect. As a further indication of the high sample quality, measurements to 17T at 0.3K show indications of the v = 2/3 fractional quantum Hall effect.

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.

Effect of the Introduction of a MBE Buffer Layer on the Morphology of InSb Almbe Layers Grown on InP Substrates

1995 ◽  
Vol 399 ◽  
Author(s):  
J.C. Ferrer ◽  
A. Cornet ◽  
F. Peiró ◽  
J.R. Morante ◽  
T. Utzmeier ◽  
...  
Keyword(s):  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
Lattice Mismatch ◽  
Three Dimensional ◽  
Atomic Layer ◽  
Buffer Layers ◽  
Dislocation Network ◽  
Threading Dislocation ◽  
Large Lattice Mismatch ◽  
Inp Substrates

ABSTRACTIn this paper we report on the morphology of InSb layers grown by atomic layer molecular beam epitaxy (ALMBE) onto InP substrates at low temperatures (330<T<400°C), comparing the nature and densities of defects with those found in ALMBE InSb films grown over InSb/InP buffer layers grown by molecular beam epitaxy (MBE). The main types of defects for ALMBE direct layers are threading dislocations and stacking faults with similar defect densities along both á110ñ directions. The inclusion of the intermediate InSb/InP MBE grown buffer layers leads to lower threading dislocation densities but higher and anisotropic stacking fault distribution. Moreover, different types of three-dimensional defects appear, which are associated with pyramidal or truncated pyramidal hillocks on the surface. These defects, consisting in twins associations are originated at the InSb/InP MBE interface and they are induced by an anomalous growth of InSb layers. In all the cases, the strain caused by the large lattice mismatch is accommodated by means of a pure edge-type misfit dislocation network placed at the interface.

Defects in HgCdTe grown by molecular beam epitaxy on GaAs substrates

2012 ◽  
Vol 20 (4) ◽  
Author(s):  
I. Izhnin ◽  
A. Izhnin ◽  
H. Savytskyy ◽  
O. Fitsych ◽  
N. Mikhailov ◽  
...  
Keyword(s):  
Optical Properties ◽  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
Buffer Layers ◽  
Structural Defects ◽  
Donor Concentration ◽  
Ion Milling ◽  
Electrical And Optical Properties ◽  
Gaas Substrates ◽  
Cdte Buffer

AbstractThe Hall effect and photoluminescence measurements combined with annealing and/or ion milling were used to study the electrical and optical properties of HgCdTe films grown by molecular-beam epitaxy on GaAs substrates with ZnTe and CdTe buffer layers. Unintentional donor doping, likely from the substrate, which resulted in residual donor concentration of the order of 1015 cm−3, was observed in the films. Also, acceptor states, possibly related to structural defects, were observed.

scholarly journals Selective Area Growth and Structural Characterization of GaN Nanostructures on Si(111) Substrates

Crystals ◽  
2018 ◽  
Vol 8 (9) ◽  
pp. 366 ◽  
Author(s):  
Alexana Roshko ◽  
Matt Brubaker ◽  
Paul Blanchard ◽  
Todd Harvey ◽  
Kris Bertness
Keyword(s):  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
Lattice Mismatch ◽  
Buffer Layers ◽  
Selective Area Growth ◽  
Gan Nanowires ◽  
Selective Area ◽  
Area Growth ◽  
Eutectic Formation

Selective area growth (SAG) of GaN nanowires and nanowalls on Si(111) substrates with AlN and GaN buffer layers grown by plasma-assisted molecular beam epitaxy was studied. For N-polar samples filling of SAG features increased with decreasing lattice mismatch between the SAG and buffer. Defects related to Al–Si eutectic formation were observed in all samples, irrespective of lattice mismatch and buffer layer polarity. Eutectic related defects in the Si surface caused voids in N-polar samples, but not in metal-polar samples. Likewise, inversion domains were present in N-polar, but not metal-polar samples. The morphology of Ga-polar GaN SAG on nitride buffered Si(111) was similar to that of homoepitaxial GaN SAG.

Effect of V/III Ratio on the Properties of GaN Layers Grown by Molecular Beam Epitaxy Using NH3

1998 ◽  
Vol 512 ◽  
Author(s):  
N. Grandjean ◽  
M. Leroux ◽  
J. Massies ◽  
M. Mesrine ◽  
P. Lorenzini
Keyword(s):  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
Flux Ratio ◽  
Buffer Layers ◽  
Force Microscopy ◽  
Sapphire Substrates ◽  
Atomic Force ◽  
Piezoelectric Field ◽  
Secondary Ion

ABSTRACTAmmonia as nitrogen precursor has been used to grow III-V nitrides by molecular beam epitaxy (MBE) on c-plane sapphire substrates. The efficiency of NH3 has been evaluated allowing the determination of the actual V/III flux ratio used during the GaN growth. The effects of the V/III ratio variation on the GaN layer properties have been investigated by photoluminescence (PL), Hall measurements, atomic force microscopy (AFM), and secondary ion mass spectroscopy (SIMS). It is found that a high V/III ratio leads to the best material quality. Optimized GaN thick buffer layers have been used to grow GaN/AlGaN quantum well (QW) heterostructures. Their PL spectra exhibit well resolved emission peaks for QW thicknesses varying from 3 to 15 monolayers. From the variation of the QW energies as a function of well width, a piezoelectric field of 450 kV/cm is deduced.

Molecular Beam Epitaxy of GaSb on GaAs Substrates with Compositionally Graded LT-GaAs x Sb 1- x Buffer Layers

2017 ◽  
Vol 34 (1) ◽  
pp. 018101
Author(s):  
Hai-Long Yu ◽  
Hao-Yue Wu ◽  
Hai-Jun Zhu ◽  
Guo-Feng Song ◽  
Yun Xu
Keyword(s):  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
Buffer Layers ◽  
Gaas Substrates ◽  
Lt Gaas
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