Effect of Substrate Temperature on Structural and Optical Properties of ZnO:Co Thin Films Fabricated by Laser Molecular Beam Epitaxy

2013 ◽  
Vol 834-836 ◽  
pp. 64-69
Author(s):  
Xian Gang Wang
Keyword(s):  
Thin Films ◽  
Molecular Beam Epitaxy ◽  
Substrate Temperature ◽  
Photoelectron Spectroscopy ◽  
Molecular Beam ◽  
X Ray Diffraction ◽  
Structural And Optical Properties ◽  
Axis Orientation ◽  
X Ray ◽  
Laser Molecular Beam Epitaxy

We synthesized ZnO:Co thin films on sapphire (0001) substrates by laser molecular beam epitaxy (LMBE) method. X-ray diffraction (XRD) spectra indicated that all samples possessed wurtzite structure with the preferential c-axis-orientation and the value of the c-axis lattice decreased with increasing substrate temperature. UVvis transmittance spectra and X-ray photoelectron spectroscopy (XPS) implied that Co2+ions incorporated into ZnO lattice with substitution for Zn2+ions and the non-bivalent Zn existed in as-prepared thin films. Two emission bands located at 418 nm (2.97 eV) and 490 nm (2.53 eV) were observed from the photoluminescence (PL) spectra of all samples. The two emission bands were in relation to Zn interstitials and the complex of VOand Zni(VOZni). The quantity of the Zn interstitials remained mostly invariable as substrate temperature increased.

Structural and Optical Properties of Zn1-XCoXO Thin Films Fabricated by Laser Molecular Beam Epitaxy

2011 ◽  
Vol 295-297 ◽  
pp. 1958-1963
Author(s):  
Jing Zhi Yang ◽  
Li Juan Fu ◽  
Xiao Peng Qi ◽  
Hong Yun Li
Keyword(s):  
Thin Films ◽  
Molecular Beam Epitaxy ◽  
Photoelectron Spectroscopy ◽  
Molecular Beam ◽  
Ambient Pressure ◽  
Visible Region ◽  
Hexagonal Structure ◽  
Axis Orientation ◽  
X Ray ◽  
Laser Molecular Beam Epitaxy

Zn1-xCoxO thin films on sapphire (0001) substrates were synthesized by laser molecular beam epitaxy (LMBE) method at various temperatures under a work ambient pressure of 5.0 x 10-5Pa condition. X-ray diffraction (XRD) spectra, UV–visible transmission spectra and X-ray photoelectron spectroscopy (XPS), photoluminescence (PL) spectra were employed to characterize the properties of samples. All samples were of wurtzite hexagonal structure with the preferential c-axis-orientation. Co2+ions incorporated into ZnO lattice and substituted for Zn2+ions. ZnLMM Auger spectrum implied Zn interstitials existed in sample. The optical transmission of all samples was relatively high in visible region. Two PL emission peaks located at 418 nm and 490 nm were assigned to the electron transition from the Zn interstitials to the top of the valence band and from the Zn interstitials to the Zn vacancies, respectively.

scholarly journals Origin of Ultraviolet Luminescence from Bulk ZnO Thin Films Grown by Molecular Beam Epitaxy

2011 ◽  
Vol 1 ◽  
pp. 135-139 ◽  
Author(s):  
M. Asghar ◽  
Khalid Mahmood ◽  
Adnan Ali ◽  
M.A. Hasan ◽  
I. Hussain ◽  
...  
Keyword(s):  
Thin Films ◽  
Raman Spectroscopy ◽  
Molecular Beam Epitaxy ◽  
Room Temperature ◽  
Molecular Beam ◽  
Energy Dispersive ◽  
Zno Thin Films ◽  
X Ray Diffraction ◽  
X Ray ◽  
Uv Luminescence

Origin of ultraviolet (UV) luminescence from bulk ZnO has been investigated with the help of photoluminescence (PL) measurements. Thin films of ZnO having 52%, 53% and 54% of Zn-contents were prepared by means of molecular beam epitaxy (MBE). We observed a dominant UV line at 3.28 eV and a visible line centered at 2.5 eV in the PL spectrum performed at room temperature. The intensity of UV line has been found to depend upon the Zn percentage in the ZnO layers. Thereby, we correlate the UV line in our samples with the Zn-interstitials-bound exciton (Zni-X) recombination. The results obtained from, x-ray diffraction, the energy dispersive X-ray spectrum (EDAX) and Raman spectroscopy supported the PL results.

High-Quality GaN Grown by Molecular Beam Epitaxy on Ge(001)

1999 ◽  
Vol 572 ◽  
Author(s):  
H. Siegle ◽  
Y. Kim ◽  
G. S. Sudhir ◽  
J. Kruger ◽  
P. Perlin ◽  
...  
Keyword(s):  
Molecular Beam Epitaxy ◽  
Low Temperatures ◽  
Molecular Beam ◽  
Substrate Material ◽  
X Ray Diffraction ◽  
Structural And Optical Properties ◽  
Alternative Substrate ◽  
X Ray ◽  
Force Microscopy ◽  
Atomic Force

ABSTRACTWe report on growth of GaN on Germanium as an alternative substrate material. The GaN films were deposited on Ge(001) substrates by plasma-assisted molecular beam epitaxy. Atomic force microscopy, x-ray diffraction, photoluminescence, and Raman spectroscopy were used to characterize the structural and optical properties of the films. We observed that the Ga/N ratio plays a crucial role in determining the phase purity and crystal quality. Under N-rich conditions the films were phase-mixed, containing cubic and hexagonal GaN, while in the Ga-rich regime they were purily hexagonal. The latter samples show bandedge luminescence with linewidths as small as 31 meV at low temperatures.

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.

scholarly journals Growth and Characterization of M-Plane GaN Thin Films Grown on γ-LiAlO2 (100) Substrates

Scanning ◽  
2017 ◽  
Vol 2017 ◽  
pp. 1-7
Author(s):  
Yu-Chiao Lin ◽  
Ikai Lo ◽  
Hui-Chun Shih ◽  
Mitch M. C. Chou ◽  
D. M. Schaadt
Keyword(s):  
Thin Films ◽  
High Resolution ◽  
Molecular Beam Epitaxy ◽  
Surface Morphology ◽  
Molecular Beam ◽  
Flux Ratio ◽  
Anisotropic Growth ◽  
X Ray Diffraction ◽  
X Ray

M-plane GaN thin films were grown on LiAlO2 substrates under different N/Ga flux ratios by plasma-assisted molecular beam epitaxy. An anisotropic growth of M-plane GaN was demonstrated against the N/Ga flux ratio. As the N/Ga flux ratio decreased by increasing Ga flux, the GaN surface trended to a flat morphology with stripes along [112-0]. According to high-resolution X-ray diffraction analysis, Li5GaO4 was observed on the interface between GaN and LiAlO2 substrate. The formation of Li5GaO4 would influence the surface morphology and crystal quality.

PREFERENTIAL ORIENTATION GROWTH OF AlN THIN FILMS ON Si(111) SUBSTRATES BY PLASMA-ASSISTED MOLECULAR BEAM EPITAXY

2009 ◽  
Vol 16 (06) ◽  
pp. 925-928 ◽  
Author(s):  
L. S. CHUAH ◽  
Z. HASSAN ◽  
H. ABU HASSAN
Keyword(s):  
Thin Films ◽  
Raman Spectroscopy ◽  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
X Ray Diffraction ◽  
X Ray ◽  
Micro Raman Spectroscopy ◽  
Raman Modes ◽  
Orientation Growth ◽  
Good Agreement

This article reports the use of plasma-assisted molecular beam epitaxy (MBE) to grow AlN on Si (111) substrate at 850°C under UHV conditions for 15, 30, and 45 min. The films were characterized by high-resolution X-ray diffraction (HR-XRD) and micro-Raman spectroscopy. XRD measurement revealed that the AlN was epitaxially grown on Si (111). Micro-Raman result showed that all the allowed Raman modes of AlN and Si were clearly visible. Fourier transform infrared (FTIR) spectroscopy has been used to investigate the A1 (LO) and E1 (TO) modes with frequencies (890–899) cm-1 and (668–688) cm-1, respectively. The results are in good agreement with reported phonon frequencies of AlN grown on Si (111).

scholarly journals Growth and Characterisation Studies of Eu3O4 Thin Films Grown on Si/SiO2 and Graphene

Nanomaterials ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1598
Author(s):  
Razan O. M. Aboljadayel ◽  
Adrian Ionescu ◽  
Oliver J. Burton ◽  
Gleb Cheglakov ◽  
Stephan Hofmann ◽  
...  
Keyword(s):  
Thin Films ◽  
Photoelectron Spectroscopy ◽  
Molecular Beam ◽  
Mixed Valence ◽  
Oxide Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Sio2 Substrate ◽  
Optical Images ◽  
The Eu

We report the growth, structural and magnetic properties of the less studied Eu-oxide phase, Eu3O4, thin films grown on a Si/SiO2 substrate and Si/SiO2/graphene using molecular beam epitaxy. The X-ray diffraction scans show that highly textured crystalline Eu3O4(001) films are grown on both substrates, whereas the film deposited on graphene has a better crystallinity than that grown on the Si/SiO2 substrate. The SQUID measurements show that both films have a Curie temperature of ∼5.5±0.1 K, with a magnetic moment of ∼320 emu/cm3 at 2 K. The mixed valence of the Eu cations has been confirmed by the qualitative analysis of the depth-profile X-ray photoelectron spectroscopy measurements with the Eu2+:Eu3+ ratio of 28:72. However, surprisingly, our films show no metamagnetic behaviour as reported for the bulk and powder form. Furthermore, the microscopic optical images and Raman measurements show that the graphene underlayer remains largely intact after the growth of the Eu3O4 thin films.

FERROMAGNETISM IN Fe-DOPED ZnO THIN FILMS

2009 ◽  
Vol 23 (06) ◽  
pp. 815-824 ◽  
Author(s):  
R. B. ZHAO ◽  
D. L. HOU ◽  
Y. Y. WEI ◽  
Z. Z. ZHOU ◽  
C. F. PAN ◽  
...  
Keyword(s):  
Thin Films ◽  
Photoelectron Spectroscopy ◽  
Exchange Coupling ◽  
Room Temperature ◽  
Room Temperature Ferromagnetism ◽  
X Ray Diffraction ◽  
Axis Orientation ◽  
X Ray ◽  
Si Substrates ◽  
Fe Ions

Zn 1-x Fe x O (x = 0.04, 0.06, 0.08, 0.10, 0.12) thin films were grown on Si substrates using reactive magnetron sputtering. X-ray diffraction analyses show that the samples have wurtzite structures with the c-axis orientation. X-ray photoelectron spectroscopy results indicate that the Fe ions are in a +2 charge state in the films. Magnetization measurements indicate that room temperature ferromagnetism is present in films annealed in vacuum while films annealed in air were non-magnetic. The presence of oxygen vacancies in these films may mediate exchange coupling of the dopant ions, resulting in room temperature ferromagnetism.

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