X-Ray Characterization of Nanostructured Semiconductor Short-Period Superlattices

2002 ◽  
Vol 749 ◽  
Author(s):  
Jianhua Li ◽  
S. C. Moss ◽  
V. Holy ◽  
A.G. Norman ◽  
A. Mascarenhas ◽  
...  
Keyword(s):  
Film Growth ◽  
Substrate Surface ◽  
Cost Effective ◽  
Mbe Growth ◽  
X Ray ◽  
Composition Modulation ◽  
Global Strain ◽  
Cost Effective Approach ◽  
Short Period ◽  
Short Period Superlattices

ABSTRACTSpontaneous lateral composition modulation during semiconductor thin film growth offers a particularly versatile and cost-effective approach to manufacture nanoscale devices. Recent experimental and theoretical studies have revealed that regular lateral composition modulation can be achieved via MBE growth of the so-called short-period superlattices and can be optimized via appropriate control of the global strain, substrate surface, and processing conditions. To characterize this phenomenon, we used synchrotron x-ray scattering to identify the interfacial morphology and laterally modulated composition profile of nearly strain-balanced InAs/AlAs short-period superlattices. Our results were compared with a theoretical model. It is shown that the lateral composition modulation is predominately caused by a vertically correlated morphlogical undulation of the superlattice layers.

scholarly journals Microstructure of Compositionally Modulated InAlAs

1996 ◽  
Vol 441 ◽  
Author(s):  
R. D. Twesten ◽  
J. Mirecki Millunchick ◽  
S. P. Ahrenkielt ◽  
Yong Zhangt ◽  
S. R. Lee ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Growth Front ◽  
Wavelength Modulation ◽  
Reciprocal Space Mapping ◽  
X Ray ◽  
Composition Modulation ◽  
Transmission Electron ◽  
Short Period ◽  
Short Period Superlattices

AbstractWe have observed spontaneous, lateral composition modulation in tensile InAlAs alloy films grown as short-period superlattices on InP (001). We have analyzed these films using transmission electron microscopy, x-ray reciprocal space mapping, and polarized photoluminescence spectroscopy. We find the growth front is nonplanar, exhibiting ∼2nm deep cusps aligned with the In-rich regions of the compositionally modulated films. In addition to the measured 15nm wavelength modulation in the [110] direction, a modulation of 30nm wavelength is seen in the orthogonal [110] direction. The photoluminescence from the modulated layer is strongly polarized and red shifted by 0.22eV.

scholarly journals High Resolution X-Ray Diffraction Investigations of Si/SiGe Quantum Well Structures and Si/Ge Short-Period Superlattices

1993 ◽  
Vol 84 (3) ◽  
pp. 475-489
Author(s):  
G. Bauer ◽  
E. Koppensteiner ◽  
P. Hamberger ◽  
J. Nützel ◽  
G. Abstreiter ◽  
...  
Keyword(s):  
High Resolution ◽  
Quantum Well ◽  
X Ray Diffraction ◽  
Quantum Well Structures ◽  
X Ray ◽  
Short Period ◽  
Short Period Superlattices

X-ray double crystal diffraction and Raman spectra measurements of AlP/GaP short-period superlattices

1999 ◽  
Vol 14 (8) ◽  
pp. 727-730 ◽  
Author(s):  
Fujia Zhang ◽  
Dejiang Zhang ◽  
Jie Zhang ◽  
Jing Qi ◽  
Yanyun Wang ◽  
...  
Keyword(s):  
Raman Spectra ◽  
Double Crystal ◽  
X Ray ◽  
Short Period ◽  
Short Period Superlattices

The crossover of preferred orientation in TiN film growth: A real time x-ray scattering study

1997 ◽  
Vol 12 (1) ◽  
pp. 9-12 ◽  
Author(s):  
J. H. Je ◽  
D. Y. Noh ◽  
H. K. Kim ◽  
K. S. Liang
Keyword(s):  
Real Time ◽  
Film Growth ◽  
Substrate Surface ◽  
Rf Sputtering ◽  
Growth Front ◽  
Surface Topology ◽  
Ex Situ ◽  
X Ray ◽  
X Ray Scattering ◽  
Ray Scattering

The orientational crossover phenomena in a radio-frequency (rf) sputtering growth of TiN films were studied in a real-time synchrotron x-ray scattering experiment. Following the initial random nucleation and growth stage, the growth was dominated by the grains with the (002) planes aligned with the substrate surface. Surprisingly, at later stages, the grains with the (002) growth front tilted away from the surface by about 60° became dominant. The tilting of the growth front resulted in a faceted surface topology that was confirmed by an ex situ AFM study. Our x-ray results suggest that the crossover was driven by the competition between the surface and the strain energy

scholarly journals Intermixing and lateral composition modulation in GaAs/GaSb short period superlattices

2003 ◽  
Vol 94 (3) ◽  
pp. 1667-1675 ◽  
Author(s):  
C. Dorin ◽  
J. Mirecki Millunchick ◽  
C. Wauchope
Keyword(s):  
Composition Modulation ◽  
Short Period ◽  
Short Period Superlattices

Profiling Composition Variations in Composition-Modulated GaP/InP Short-Period Superlattices Using Resonance Raman Scattering

1999 ◽  
Vol 583 ◽  
Author(s):  
H. M. Cheong ◽  
Yong Zhang ◽  
A. G. Norman ◽  
J. D. Perkins ◽  
A. Mascarenhas ◽  
...  
Keyword(s):  
Raman Scattering ◽  
Band Gap ◽  
Resonance Raman ◽  
Band Gap Energy ◽  
Resonance Raman Scattering ◽  
Rich Region ◽  
Gap Energy ◽  
Composition Modulation ◽  
Short Period ◽  
Short Period Superlattices

AbstractWe use resonance Raman scattering (RRS) and electroreflection (ER) measurements to profile the the composition and strain variations in laterally composition-modulated (CM) GaP/InP short-period superlattices (SPS's). The ER spectra of a GaP2.2/InP2.0 SPS give the fundamental band-gap energy at 1.69±0.05eV, which is about 210 meV lower than the band gap energy of a GaInP random alloy with the same overall composition. The RRS measurements reveal strong dependences of the phonon spectrum on the polarization and the excitation energy. In RRS spectra measured with the polarization of both excitation and scattered photons along the composition modulation direction, the GaP-like longitudinal optical (LO) phonon redshifts by 4.0±0.5 cm−1 near the resonance with the fundamental energy gap. On the other hand, when the polarizations are orthogonal to the composition modulation, the LO phonons redshift as much as 16 cm−1 at low excitation energies. A comparison of the experimental data with a model calculation gives the average In composition in the In-rich region as 0.70±0.02, and the average Ga composition in the Ga-rich region as 0.68±0.02. Our result also indicates that there are small volumes (less than 1% volume fraction) with very high In mole fraction.

Double Periodicity Formation in EuTe/PbTe Superlattices

1995 ◽  
Vol 399 ◽  
Author(s):  
M. Shima ◽  
L. Salamanca-Riba ◽  
G. Springholz ◽  
G. Bauer
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Short Period ◽  
Short Period Superlattices

ABSTRACTMolecular beam epitaxy was used to grow EuTe(x)/PbTe(y) short period superlattices with x=1-4 EuTe(111) monolayers alternating with y≈3x PbTe monolayers. The superlattices were characterized by transmission electron microscopy and high resolution x-ray diffraction. Regions with double periodicity were observed coexisting with areas of nominal periodicity. The sample with x=3.5 and y=9, for example, contains regions with double periodicity of x=7 and y=17. X-ray diffraction measurements confirm the formation of the double periodicity in these samples by the appearance of weak satellites in between the satellites of the nominal periodicity. The double periodicity in the superlattice is believed to result from interdiffusion during the growth. A model for this process is presented.

Parallel Bias-Enhanced Sulfur-Assisted Chemical Vapor Deposition of Nanocrystalline Diamond Films

2003 ◽  
Vol 775 ◽  
Author(s):  
Joel De Jesùs ◽  
Juan A. Gonzàlez ◽  
Oscar O. Ortiz ◽  
Brad R. Weiner ◽  
Gerardo Morell
Keyword(s):  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Photoelectron Spectroscopy ◽  
Film Growth ◽  
Defect Density ◽  
Substrate Surface ◽  
Chemical Vapor ◽  
Nanocrystalline Diamond ◽  
X Ray ◽  
Positively Charged

AbstractThe transformations induced by the application of a continuous bias voltage parallel to the growing surface during the sulfur-assisted hot-filament chemical vapor deposition (HFCVD) of nanocrystalline diamond (n-D) films were investigated by Raman spectroscopy (RS), scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The films were deposited on molybdenum substrates using CH4, H2 and H2S. Bias voltages in the range of 0 – 800 VDC were applied parallel to the substrate surface continuously during deposition. The study revealed a significant improvement in the films' density and a lowering in the defect density of the nanocrystalline diamond structure for parallel bias (PB) voltages above 400V. These high PB conditions cause the preferential removal of electrons from the gaseous environment, thus leading to the net accumulation of positive species in the volume above the growing film, which enhances the secondary nucleation. The nanoscale carbon nuclei self-assemble into carbon nano-clusters with diameters in the range of tens of nanometers, which contain diamond (sp3-bonded C) in their cores and graphitic (sp2-bonded C) enclosures. Hence, the observed improvement in film density and in atomic arrangement appears to be connected to the enhanced presence of positively charged ionic species, consistent with models which propose that positively charged carbon species are the crucial precursors for CVD diamond film growth.

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