Vibrational Modes and Crystallographic Structure of Cd3As2 and (Cd1-xZnx)3As2 Epilayers

2021 ◽  
Author(s):  
Brian Fluegel ◽  
Anthony Rice ◽  
Kirstin Alberi
Keyword(s):  
Molecular Beam ◽  
Scattering Amplitude ◽  
Crystallographic Structure ◽  
Amplitude Dependence ◽  
Vibrational Modes ◽  
Narrow Linewidth ◽  
Polarization Analysis ◽  
Dirac Semimetal ◽  
Zn Concentration ◽  
Improved Accuracy

Abstract Low-temperature Raman scattering is used to study the crystal structure of molecular-beam epitaxially grown layers of the Dirac semimetal Cd3As2 and its related alloy (Cd1-xZnx)3As2. The combination of narrow-linewidth spectra, multiple growth directions and full polarization analysis allows improved accuracy in identifying the irreducible representation of over 57 Raman-active vibrations. Several disagreements with previous identifications are found. Structurally, the results agree with the centrosymmetric I41/acd space group of bulk-grown Cd3As2 and are clearly distinct from the Raman spectra of nanoscale platelets and wires. 3-fold twinning is seen in (112) Cd3As2 grown on (111) zincblende substrates corresponding to the three possible tetragonal orientations. In dilute (Cd1-xZnx)3As2, phonons have a frequency and scattering amplitude dependence on Zn concentration that is continuous with Cd3As2 but at least one frequency is absent at the alloy endpoint, preventing a simple one-mode description of the alloy phonon.

Local vibrational modes of H complexes in Mg-doped GaN grown by molecular beam epitaxy

2004 ◽  
Vol 84 (6) ◽  
pp. 897-899 ◽  
Author(s):  
R. Cuscó ◽  
L. Artús ◽  
D. Pastor ◽  
F. B. Naranjo ◽  
E. Calleja
Keyword(s):  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
Vibrational Modes ◽  
Local Vibrational Modes ◽  
Mg Doped

scholarly journals Molecular beam epitaxy of three-dimensionally thick Dirac semimetal Cd3As2 films

APL Materials ◽  
2019 ◽  
Vol 7 (7) ◽  
pp. 071109 ◽  
Author(s):  
Y. Nakazawa ◽  
M. Uchida ◽  
S. Nishihaya ◽  
S. Sato ◽  
A. Nakao ◽  
...  
Keyword(s):  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
Dirac Semimetal

scholarly journals Topological Dirac semimetal Na3Bi films in the ultrathin limit via alternating layer molecular beam epitaxy

APL Materials ◽  
2018 ◽  
Vol 6 (8) ◽  
pp. 086103 ◽  
Author(s):  
Igor V. Pinchuk ◽  
Thaddeus J. Asel ◽  
Andrew Franson ◽  
Tiancong Zhu ◽  
Yuan-Ming Lu ◽  
...  
Keyword(s):  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
Dirac Semimetal

Raman Scattering Characterization of GaAs-AlAs Superlattices Grown Along the [110] Direction

1987 ◽  
Vol 102 ◽  
Author(s):  
D. Kirillov ◽  
Yi-Ching Pao
Keyword(s):  
Raman Scattering ◽  
Molecular Beam ◽  
Transverse Optical ◽  
Crystallographic Structure ◽  
Optical Phonons ◽  
Lower Intensity ◽  
Dominant Feature ◽  
First Time

ABSTRACTRaman spectra of the GaAs-AlAs superlattice grown by molecular beam epi-taxy along the [110] direction were studied for the first time. The spectra were compared with spectra of the [100] superlattice and differences due to different crystallographic structure were analyzed. It was found that the energies of folded acoustical modes are higher in the [110] superlattice due to higher sound velocity in the [110] direction. Confined transverse optical phonons were a dominant feature of the spectrum of the [110] superlattice which allowed observation of the folding of transverse optical phonons. Stronger intensity of interface modes and lower intensity of folded acousti-cal modes in the [110] superlattice indicated that the quality of the layer interfaces was worse than in the [100] superlattice.

scholarly journals Influence of Doping on the Lattice Dynamics of Gallium Nitride

1999 ◽  
Vol 4 (S1) ◽  
pp. 327-332 ◽  
Author(s):  
A. Kaschner ◽  
H. Siegle ◽  
A. Hoffmann ◽  
C. Thomsen ◽  
U. Birkle ◽  
...  
Keyword(s):  
Molecular Beam Epitaxy ◽  
Lattice Dynamics ◽  
Molecular Beam ◽  
High Energy ◽  
Host Lattice ◽  
Free Carrier ◽  
Vibrational Modes ◽  
Local Vibrational Modes ◽  
Secondary Ion ◽  
Mg Doped

We present results of Raman-scattering experiments on GaN doped with Si, C, and Mg, respectively, grown by molecular beam epitaxy (MBE). The influence of the different dopants on strain and free-carrier concentration was investigated. Furthermore, we report on several local vibrational modes (LVM) around 2200 cm−1 in Raman spectra of highly Mg-doped GaN. A possible explanation of these high-energy modes in terms of hydrogen-related vibrations is given. We also found a variety of new structures in the range of the GaN host lattice phonons. Secondary ion mass spectroscopy (SIMS) was applied to determine the concentration of magnesium and unintentionally incorporated hydrogen.

Cubic ZnxMg1−xO thin films grown by plasma-assisted molecular-beam epitaxy for optoelectronic applications

2010 ◽  
Vol 25 (6) ◽  
pp. 1072-1079 ◽  
Author(s):  
J.W. Mares ◽  
R.C. Boutwell ◽  
A. Scheurer ◽  
W.V. Schoenfeld
Keyword(s):  
Thin Films ◽  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
Phase Segregation ◽  
Band Gap Energy ◽  
X Ray Diffraction ◽  
X Ray ◽  
Zn Concentration ◽  
Zinc Concentrations ◽  
Lattice Matched

Heteroepitaxial ZnxMg1−xO thin films were grown on lattice-matched MgO (100) substrates using radiofrequency plasma-assisted molecular-beam epitaxy. High-quality epilayers with zinc concentrations ranging from x = 0 (MgO) to x = 0.65 were grown and characterized optically, structurally, and electrically. The ZnxMg1−xO films were found to maintain the rocksalt cubic (B1) crystal structure for concentrations z < 0.65, with a linear dependence of lattice constant on Zn concentration. X-ray diffraction (XRD) also revealed the emergence of phase segregation into wurtzite (B4) phase for the highest concentration film. The band gap energy of the films was successfully varied from 4.9 to 6.2 eV (253–200 nm), showing a linear relationship with Zn concentration. The strictly cubic films exhibit roughness on the order of 10 Å and resistivities of approximately 106 Ω·cm.

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