Growth of heteroepitaxial GaSb thin films on Si(100) substrates

2004 ◽  
Vol 19 (8) ◽  
pp. 2315-2321 ◽  
Author(s):  
Thang Nguyen ◽  
Walter Varhue ◽  
Edward Adams ◽  
Mark Lavoie ◽  
Stephen Mongeon

The heteroepitaxial growth of GaSb thin films on Si(100) and GaAs(100) substrates is presented. The growth technique involves the use of atomic Ga and Sb species, which are provided by thermal effusion and radio frequency sputtering, respectively. The crystalline quality of the heteroepitaxial GaSb film on the Si substrate is high despite the larger lattice mismatch. Epitaxial quality is determined by high-resolution x-ray diffraction and Rutherford backscatter spectrometry channeling. Atomic-force microscopy is used to monitor the evolution of surface morphology with increasing film thickness. Transmission electron microscopy shows the formation of stacking faults at the Si/GaSb interface and their eventual annihilation with increasing GaSb film thickness. Annihilation of stacking faults occurs when two next-neighbor mounds meet during the overgrowth of a common adjacent mound.

1994 ◽  
Vol 359 ◽  
Author(s):  
S. Henke ◽  
K.H. Thürer ◽  
S. Geier ◽  
B. Rauschenbach ◽  
B. Stritzker

ABSTRACTOn mica(001) thin C60-films are deposited by thermal evaporation at substrate temperatures from room temperature up to 225°C. The dependence of the structure and the epitaxial alignment of the thin C60-films on mica(001) on the substrate temperature and the film thickness up to 1.3 μm at a well-defined deposition rate (0.008 nm/s) is investigated by atomic force microscopy and X-ray diffraction. The shape and the size of the C60-islands, which have an influence on the film quality at larger film thicknesses, are sensitively dependent on the substrate temperature. At a film thickness of 200 nm the increase of the substrate temperature up to 225°C leads to smooth, completely coalesced epitaxial C60-thin films characterized by a roughness smaller than 1.5 nm, a mosaic spread Δω of 0.1° and an azimuthal alignment ΔΦ of 0.45°.


1999 ◽  
Vol 597 ◽  
Author(s):  
M. Siegert ◽  
Judit G. Lisoni ◽  
C. H. Lei ◽  
A. Eckau ◽  
W. Zander ◽  
...  

AbstractIn the process of developing thin film electro-optical waveguides we investigated the influence of different substrates on the optical and structural properties of epitaxial BaTiO3 thin films. These films are grown by on-axis pulsed laser deposition (PLD) on MgO(100), MgAl2O4(100), SrTiO3(100) and MgO buffered A12O3(1102) substrates. The waveguide losses and the refractive indices were measured with a prism coupling setup. The optical data are correlated to the results of Rutherford backscattering spectrometry/ion channeling (RBS/C). X-ray diffraction (XRD), atomic force microscopy (AFM) and transmission electron microscopy (TEM). BaTiO3 films on MgO(100) substrates show planar waveguide losses of 3 dB/cm and ridge waveguide losses of 5 dB/cm at a wavelength of 633 nm.


1996 ◽  
Vol 436 ◽  
Author(s):  
Cengiz S. Ozkan ◽  
William D. Nix ◽  
Huajian Gao

AbstractHeteroepitaxial Si1-xGex. thin films deposited on silicon substrates exhibit surface roughening via surface diffusion under the effect of a compressive stress which is caused by a lattice mismatch. In these films, surface roughening can take place in the form of ridges which can be aligned along <100> or <110> directions, depending on the film thickness. In this paper, we investigate this anisotropic dependence of surface roughening and present an analysis of it. We have studied the surface roughening behaviour of 18% Ge and 22% Ge thin films subjected to controlled annealing experiments. Transmission electron microscopy and atomic force microscopy have been used to study the morphology and microstructure of the surface ridges and the dislocations that form during annealing.


2015 ◽  
Vol 821-823 ◽  
pp. 213-216
Author(s):  
S.M. Ryndya ◽  
N.I. Kargin ◽  
A.S. Gusev ◽  
E.P. Pavlova

Silicon carbide thin films were obtained on Si (100) and (111) substrates by means of vacuum laser ablation of α-SiC ceramic target. The influence of substrate temperature on composition, structure and surface morphology of experimental samples was examined using Rutherford backscattering spectrometry (RBS), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), conventional and high-resolution transmission electron microscopy (TEM/HRTEM), atomic force microscopy (AFM), selected area electron diffraction (SAED) and X-ray diffraction (XRD) methods.


2011 ◽  
Vol 15 (1) ◽  
pp. 49-55
Author(s):  
V. Dhanasekaran ◽  
T. Mahalingam ◽  
S. Rajendran ◽  
Jin Koo Rhee ◽  
D. Eapen

CuO thin films were coated on ITO substrates by an electrodeposition route through potentiostatic mode. The electrodeposited CuO thin films were characterized and the role of copper sulphate concentration on the structural, morphological and optical properties of the CuO films was studied. Film thickness was measured by a stylus profilometer and found to be in the range between 800 and 1400 nm. The structural characteristics studies were carried out using X-ray diffraction and found that the films are polycrystalline in nature with a cubic structure. The preferential orientation of CuO thin films is found to be along (111) plane. The estimated microstructural parameters revealed that the crystallite size increases whereas the number of crystallites per unit area decreases with increasing film thickness. SEM studies show that the grain sizes of CuO thin films vary between 100 and 150 nm and also morphologies revealed that the electrodeposited CuO exhibits uniformity in size and shape. The surface roughness is estimated 15 nm of the CuO film were studied by atomic force microscopy. Optical properties of the films were analyzed from absorption and transmittance studies. The optical band gap energy was determined to be 1.5 eV from absorption coefficient. The variation of refractive index (n), extinction coefficient (k), with wavelength was studied and the results are discussed.


2007 ◽  
Vol 14 (04) ◽  
pp. 755-759 ◽  
Author(s):  
D. U. LEE ◽  
J. H. JUNG ◽  
T. W. KIM ◽  
H. S. LEE ◽  
H. L. PARK ◽  
...  

CdTe thin films were grown on GaAs (100) substrates by using molecular beam epitaxy at various temperatures. The results of the X-ray diffraction (XRD) patterns showed that the orientation of the grown CdTe thin films was the (100) orientation. XRD patterns, atomic force microscopy images, high-resolution transmission electron microscopy (HRTEM) images, and photoluminescence spectra showed that the crystallinity of CdTe (100) epilayers grown on GaAs (100) substrates was improved by increasing the substrate temperature. HRTEM images showed that misfit dislocations existed at the CdTe / GaAs heterointerface. These results can help improve understanding of the substrate temperature effect on the structural and the optical properties of CdTe (100)/ GaAs (100) heterostructures.


1995 ◽  
Vol 10 (3) ◽  
pp. 680-691 ◽  
Author(s):  
Andreas Seifert ◽  
Fred F. Lange ◽  
James S. Speck

A mixed alkoxide liquid precursor was used to form epitaxial PbTiO3 thin films by spin-coating on cubic (001) SrTiO3 substrates. The films were heat-treated at temperatures between 380 °C/1 h and 800 °C/1 h. X-ray diffraction, atomic force microscopy, scanning and transmission electron microscopy were used to characterize the microstructure of the films and to evaluate the epitaxial phenomena. At ∼400 °C/1 h, a polycrystalline, metastable Pb-Ti fluorite crystallizes from the pyrolyzed amorphous precursor. At slightly higher temperatures (∼420 °C/1 h), the thermodynamically stable phase with the perovskite structure epitaxially nucleates at the film/substrate interface. A small number of epitaxial grains grow through the film toward the surface and consume the nanocrystalline fluorite grains. Coarsening of the perovskite grains leads to a reduction in mosaic spread during further heating. Pores, which concurrently coarsen with grain growth, produce a pitted surface as they disappear from within the film. At 800 °C/1 ha dense epitaxial PbTiO3 film with a smooth surface is observed. Parameters governing the formation of a- and c-domains are discussed as well as the small tilts of the domain axes away from the substrate normal.


2013 ◽  
Vol 24 ◽  
pp. 133-139 ◽  
Author(s):  
Madhavi Thakurdesai ◽  
A. Mahadkar ◽  
Varsha Bhattacharyya

Ion beam irradiation is a unique non-equilibrium technique for phase formation and material modification. Localized rise in temperature and ultra fast (~1012 s) dissipations of impinging energy make it an attractive tool for nanostructure synthesize. Dense electronic excitation induced spatial and temporal confinement of high energy in a narrow dimension leads the system to a highly non-equilibrium state and the system then relaxes dynamically inducing nucleation of nanocrystals along the latent track. In the present investigation, amorphous thin films of TiO2 are irradiated by 100 MeV Ag ion beam. These irradiated thin films are characterized by Atomic Force Microscopy (AFM), Glancing Angle X-ray Diffraction (GAXRD), Transmission Electron Microscopy (TEM) and UV-VIS absorption spectroscopy. AFM and TEM studies indicate formation of circular nanoparticles of size 10±2 nm in a film irradiated at a fluence of 1×1012 ions.cm-2. Nanophase formation is also inferred from the blueshift observed in UV-VIS absorption band edge.


2009 ◽  
Vol 1201 ◽  
Author(s):  
Jeremy West Mares ◽  
Ryan Casey Boutwell ◽  
Matthew Thomas Falanga ◽  
Amber Scheurer ◽  
Winston Vaughan Schoenfeld

AbstractWe report on the heteroepitaxial growth of high-quality single crystal cubic ZnxMg1-xO and NiyMg1-yO thin films by radio frequency oxygen plasma-assisted molecular beam epitaxy (RF-MBE). Film compositions over the ranges x = 0 to x = 0.65 and y = 0 to y = 1 have been grown on lattice-matched MgO (100) and characterized optically, morphologically, compositionally, and electrically. Both of these ternary materials are shown to have bandgaps which vary directly as a function of transition metal (Ni or Zn) concentration. Optical transmission measurements of NiyMg1-yO show the bandgap to shift continuously over the approximate range 3.5 eV (for NiO) to 4.81 eV (for y=0.075). Similarly, the bandgap of cubic ZnxMg1-xO is shifted from about 4.9 eV (for x = 0.65) to 6.25 eV (for x=0.12). Films exhibit good morphological quality and typical roughness of NiyMg1-yO films is 5 Å while that of ZnxMg1-xO is less than 15 Å, as measured by atomic force microscopy (AFM). X-ray diffraction (XRD) is employed to confirm crystal orientation and to determine the films' lattice constants. Film compositions are interrogated by Rutherford Backscattering (RBS) and electrical characterization is made by room-temperature Hall measurements.


2005 ◽  
Vol 872 ◽  
Author(s):  
Yuebing Zheng ◽  
Shijie Wang ◽  
Cheng Hon A. Huan

AbstractThe effect of dopants on the band structure and crystal structure of Ba0.5Sr0.5TiO3thin films on (100) LaAlO3 substrates has been investigated. The dopants include Ti, Mg and Al. The band-gap energies of the thin films were determined from the transmission spectra measured by UVVIS spectrophotometer and increased with the increase of dopant concentration regardless of the type of dopants. The crystal structure was studied by using transmission electron microscopy, atomic force microscopy, x-ray diffraction and micro-Raman spectroscopy. The relation between band structure and crystal structure was discussed.


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