Change of growth orientation in Pt films epitaxially grown on MgO(001) substrates by sputtering

2002 ◽  
Vol 17 (9) ◽  
pp. 2334-2338 ◽  
Author(s):  
Kun Ho Ahn ◽  
Sunggi Baik ◽  
Sang Sub Kim
Keyword(s):  
Deposition Rate ◽  
Surface Defects ◽  
Epitaxial Film ◽  
Growth Conditions ◽  
Gradual Transition ◽  
Growth Orientation ◽  
Orientation Change ◽  
Key Driver ◽  
Pt Films ◽  
Substrate Temperatures

A drastic change of the growth orientation in epitaxial Pt films grown by sputtering on MgO(001) was observed. At higher substrate temperatures, practically pure (001) epitaxial Pt films grow. On the other hand, epitaxial (111) Pt films grow at lower substrate temperatures. Interestingly, the gradual transition from (111) to (001) orientation occurs at lower temperatures when applied at a lower deposition rate. The degree of supersaturation in growth conditions is proposed as a key driver of the orientation change. When homogeneous nucleation occurs under a higher supersaturation, a large number of nuclei grow at the flat (001) terraces possessing (111) tetrahedral orientation. Under a lower supersaturation, a small number of nuclei aligned in (001) orientation to each other form dominantly at surface defects, resulting in a (001) epitaxial film with no grains. Our results suggest that one can selectively prepare either (001) or (111) epitaxial Pt films by properly adjusting substrate temperature and/or deposition rate.

Nucleation of Cu(In, Ga)Se2 on Molybdenum Substrates

2003 ◽  
Vol 763 ◽  
Author(s):  
T. Schlenker ◽  
K. Orgassa ◽  
H. W. Schock ◽  
J. H. Werner
Keyword(s):  
Substrate Temperature ◽  
Deposition Rate ◽  
Cluster Formation ◽  
Three Dimensional ◽  
Areal Density ◽  
Growth Conditions ◽  
Exponential Dependence ◽  
Nucleation Behavior ◽  
Substrate Temperatures ◽  
Island Density

AbstractWe investigate growth mechanisms of Cu(In, Ga)Se2 on Mo films on glass, as the typical back contact for Cu(In, Ga)Se2 solar cells. A thermal evaporation process deposits Cu(In, Ga)Se2of nominal 3 nm thickness at different rates R and substrate temperatures TSub. An ultrahigh resolution scanning electron microscope serves to investigate the nucleation behavior. The deposited Cu(In, Ga)Se2 forms three-dimensional isolated nuclei, known as Volmer-Weber growth mode. Deposition rate R and substrate temperature TSub control the areal density n of the Cu(In, Ga)Se2 nuclei. We observe a power law dependence between the island density n and the deposition rate R, and an exponential dependence of the island density n on substrate temperature TSub. The theory of homogeneous nucleation explains the Cu(In, Ga)Se2 cluster formation on polycrystalline Mo and the dependence of the island density on the growth conditions.

(111) Monocrystalline Nickel Films

1972 ◽  
Vol 30 ◽  
pp. 512-513
Author(s):  
T.E. Pratt ◽  
R.W. Vook
Keyword(s):  
Film Thickness ◽  
Deposition Rate ◽  
Room Temperature ◽  
Narrow Range ◽  
High Vacuum ◽  
Residual Pressure ◽  
Temperature Dependent ◽  
Deposition Parameters ◽  
Transmission Electron ◽  
Substrate Temperatures

(111) oriented thin monocrystalline Ni films have been prepared by vacuum evaporation and examined by transmission electron microscopy and electron diffraction. In high vacuum, at room temperature, a layer of NaCl was first evaporated onto a freshly air-cleaved muscovite substrate clamped to a copper block with attached heater and thermocouple. Then, at various substrate temperatures, with other parameters held within a narrow range, Ni was evaporated from a tungsten filament. It had been shown previously that similar procedures would yield monocrystalline films of CU, Ag, and Au.For the films examined with respect to temperature dependent effects, typical deposition parameters were: Ni film thickness, 500-800 A; Ni deposition rate, 10 A/sec.; residual pressure, 10-6 torr; NaCl film thickness, 250 A; and NaCl deposition rate, 10 A/sec. Some additional evaporations involved higher deposition rates and lower film thicknesses.Monocrystalline films were obtained with substrate temperatures above 500° C. Below 450° C, the films were polycrystalline with a strong (111) preferred orientation.

Single Wafer Amorphous Silicon Process Evaluation

1997 ◽  
Vol 467 ◽  
Author(s):  
David O'Meara ◽  
Chow Ling Chang ◽  
Roc Blumenthal ◽  
Rama I. Hegde ◽  
Lata Prabhu ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Surface Morphology ◽  
Amorphous Silicon ◽  
Deposition Rate ◽  
Cross Sections ◽  
Growth Conditions ◽  
Degree Of Crystallinity ◽  
Deposition Parameters ◽  
Before And After ◽  
Production Requirement

ABSTRACTSingle wafer amorphous silicon deposition was characterized through process modeling and film characterization for application in semiconductor production. DOE methodology was used to determine the main deposition parameters, and the responses were limited to device production requirement properties of surface roughness, deposition rate and degree of crystallinity of the as-deposited film. The data trends and models show that deposition temperature and silane flow are the main factors. Increasing either or both factor increases the deposition rate and the surface roughness. The surface morphology, evaluated by AFM, SEM and TEM, was found to be rougher at extreme growth conditions than the poly crystalline film formed after anneal. The as-deposited surface morphology was not a result of pre-anneal crystal formations as determined by TEM cross sections of samples before and after anneal. Lack of crystalinity is important for impurity diffusion considerations. Device application of the single wafer a-Si process will be a compromise between growth rate (and associated throughput) and surface roughness that can be tolerated.

Fabrication of Device-Quality Wide-Gap a-Si:H Films at Very Low Substrate Temperatures

1990 ◽  
Vol 192 ◽  
Author(s):  
Yoshihiro Hishikawa ◽  
Sadaji Tsuge ◽  
Noboru Nakamura ◽  
Shinya Tsuda ◽  
Shoichi Nakano ◽  
...  
Keyword(s):  
Deposition Rate ◽  
Light Exposure ◽  
Rf Plasma ◽  
Plasma Parameters ◽  
Solar Cell Performance ◽  
Capacitively Coupled ◽  
Bond Density ◽  
Deposition Parameters ◽  
Wide Gap ◽  
Substrate Temperatures

ABSTRACTWide-gap a-Si:H films with device quality (Tauc’s optical gap > 1.9eV, σph under AMI.5, 100mW/cm2 illumination ≥ 10−5, Ω−1cm−1, a σph/σ a≥106) have been fabricated. These films are deposited at low substrtate temperatures (TS≤80°C ) either by diluting SiH4 with H2 or optimizing the plasma parameters in a capacitively–coupled RF plasma–CVD reactor. Reduction in the SiH2 bond density and the ESR spin density are also observed. In this study, good film quality is always accompanied by a small deposition rate. Furthermore, σph is nearly the same if the deposition rate and Ts is the same, regardless of other deposition parameters. This suggests that the surface reactions or structural relaxations at the film-growing surface can produce high–quality a–Si:H films even at low TsS, if the deposition rate is low. Results in thermal annealing, light exposure, and solar cell performance confirm that these films have device quality and wide bandgap.

Influence of Substrate Temperature on Deposition Rate and Optical Properties of Aluminum Oxide Thin Films Prepared by Reactive DC Sputtering Technique

2016 ◽  
Vol 675-676 ◽  
pp. 281-284
Author(s):  
Chatpawee Hom-On ◽  
Mati Horprathum ◽  
Pitak Eiamchai ◽  
Sakson Limwichean ◽  
Viyapol Patthanasetakul ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Optical Properties ◽  
Aluminum Oxide ◽  
Substrate Temperature ◽  
Deposition Rate ◽  
Oxide Films ◽  
Chemical Compositions ◽  
Transmittance Spectra ◽  
Vis Spectroscopy ◽  
Substrate Temperatures

Aluminum oxide films were grown on (100) silicon wafers and glass substrates by pulsed dc reactive magnetron sputtering deposition. In this experiment, substrate temperatures were varied from room temperature to 500°C. Grazing-incidence X-ray diffraction (GIXRD) analysis revealed that the resulting films have amorphous structures. Field-emission scanning electron microscope (FESEM) was used to characterize the morphology of the films. The films’ optical properties were determined by UV-Vis spectroscopy. The results demonstrated that the deposition rate, the surface roughness and the transmittance spectra of the aluminum oxide films were strongly influenced by the substrate temperature. The deposition rate and the surface roughness of the films were higher at higher substrate temperatures. In the range between 100°C and 200°C, the transmittance spectra were found to be lower than those of the films deposited at other substrate temperatures. This was due to the sub-aluminum oxide condition in the films. The dependence of films’ optical properties on the substrate temperature might result from the change in chemical compositions during the sputtering process.

Mosaic Crystal Tilts and Their Relationship to Dislocation Structure, Surface Roughness and Growth Conditions in Relaxed SiGe Layers

1998 ◽  
Vol 533 ◽  
Author(s):  
D. J. Wallis ◽  
D. J. Robbins ◽  
A. J. Pidduck ◽  
G. M. Williams ◽  
A. Churchill ◽  
...  
Keyword(s):  
Surface Roughness ◽  
High Performance ◽  
Surface Defects ◽  
Growth Conditions ◽  
Buffer Layers ◽  
Great Promise ◽  
Threading Dislocation ◽  
Initial Growth ◽  
Growth Interface ◽  
Mosaic Crystal

AbstractIn recent years the growth of virtual substrates using graded SiGe buffer layers has shown great promise for the development of high performance devices. Whilst significant progress has been made in the control of growth conditions to produce low threading dislocation densities of the order suitable for commercial exploitation, several technological problems still have to be overcome. An example of such problems are cosmetic surface defects such as pits and the cross hatched surface roughness associated with mosaic crystal tilts. The work described here utilises a variety of techniques, including X-ray diffraction reciprocal space maps, TEM, AFM and SIMS to provide a comparison between several SiGe virtual substrates grown using low pressure-CVD at high (≈800°C) and low (≈6000°C) temperatures, and at different grade rates (5–50% Ge μm−1). The growth conditions are seen to have a strong effect on the crystal tilts present in the layers with the low temperature layers showing a much larger spread of mosaic tilts. The origin of these tilts is seen to occur during the early stages of the relaxation process irrespective of growth temperature and at similar Ge fractions for all samples. TEM imaging close to the initial growth interface shows that dislocation pileups occur in this region and also suggest that the pileups have a characteristic spacing of 1–2μm. A similar characteristic length scale is also observed in the surface roughness by AFM, the form of which is seen to depend upon the growth conditions.

Oxygen Atom Induced Deposition of Silicon Dioxide

1992 ◽  
Vol 282 ◽  
Author(s):  
Dimitri A. Levedakis ◽  
Gregory B. Raupp
Keyword(s):  
Silicon Dioxide ◽  
Deposition Rate ◽  
Total Pressure ◽  
Oxygen Radical ◽  
Flow Ratio ◽  
One Dimensional ◽  
Substrate Temperatures ◽  
Oxygen Discharge ◽  
Deposited Films ◽  
Deposition Conditions

ABSTRACTSilicon dioxide was deposited from tetraethylorthosilicate (TEOS) and remote microwave oxygen plasma on a heated silicon substrate in a cold-wall reactor. The deposition rate and film quality were examined as functions of substrate temperature, total pressure, absorbed plasma power and O2:TEOS flow ratio. The deposition reaction exhibited an activation energy of approximately 10 kJ/mol for substrate temperatures in the range of 323–623 K. The deposition rate reached a maximum with increasing total pressure. The rate was found to be a near-linear function of the absorbed microwave power. At fixedabsorbed power the rate reached a maximum with increasing O2:TEOS flow ratio. A one-dimensional mathematical model was developed to predict the oxygen radical concentration at the exit of the afterglow region of the oxygen discharge. Comparisons of the predicted oxygen radical concentrations with the deposition rates at corresponding deposition conditions supports the view that the overall SiO2 deposition reaction is largely controlled by the concentration of oxygen radicals. The average refractive index ofthe deposited films was 1.466 ± 0.011. Fourier transform infra-red (FTIR) transmission spectra showed significant concentrations of hydroxyls in the deposited films.

scholarly journals High temperature ferromagnetic ordering in c-axis oriented ZnO:Mn nanoparticle thin films by tailoring substrate temperature

2014 ◽  
Vol 32 ◽  
pp. 1460341 ◽  
Author(s):  
Usman Ilyas ◽  
P. Lee ◽  
T. L. Tan ◽  
R. V. Ramanujan ◽  
Sam Zhang ◽  
...  
Keyword(s):  
Thin Films ◽  
Substrate Temperature ◽  
Magnetic Measurements ◽  
Deep Level ◽  
Growth Conditions ◽  
Optical Quality ◽  
Host Matrix ◽  
X Ray ◽  
Ferromagnetic Ordering ◽  
Substrate Temperatures

This study reports the enhanced ferromagnetic ordering in ZnO:Mn nanoparticle thin films, grown at different substrate temperatures using pulsed laser deposition. The optimum growth conditions were deduced from X-ray, photoemission and magnetic measurements. The X-ray measurements reveal that there was an optimum substrate temperature where the thin films showed relatively stronger texture, better crystallinity and lower strain. Substrate temperature tuned the deep level recombination centers in ZnO:Mn , which changed the optical quality by altering the electronic structure. The M-H curves, in the present study, revealed superior ferromagnetic response of 20-nm sized particles in ZnO:Mn thin film grown at a substrate temperature of 450 °C. Ferromagnetic ordering becomes weaker at higher/lower substrate temperatures due to the activation of native defects in ZnO host matrix.

scholarly journals Growth Condition Dependence Of Rheed Pattern From GaAs (111)B Surface

1991 ◽  
Vol 228 ◽  
Author(s):  
K. Yang ◽  
W. Li ◽  
A. P. Taylor ◽  
Q.-F. Xiao ◽  
L. J. Schowalter ◽  
...  
Keyword(s):  
Experimental Data ◽  
Phase Diagram ◽  
Growth Conditions ◽  
Condition Dependence ◽  
Rheed Pattern ◽  
3 Dimensional ◽  
Ion Channeling ◽  
Surface Reconstructions ◽  
Substrate Temperatures ◽  
Rough Surface Morphology

ABSTRACTA 3-dimensional phase diagram is introduced to describe the dependence of the RHEED pattern from GaAs(111)B surface on growth conditions. The 2×2, transitional(1×1), and √19×,√19 surface reconstructions correspond to different zones in the phase diagram. A equation is given for the planes that separate these zones, which fit experimental data well. Homoepitaxial films on GaAs(111)B grown in the 2×2 region generally have bad crystal quality as determined by the ion channeling, and growth in the √19×√19 region generally yields rough surface morphology. At higher substrate temperatures (∼ 650 °C), featureless films with minimum ion channeling yields of less than 4% are achieved.

Influence of Growth Parameters and Annealing on Properties of MBE Grown GaAsSbN SQWs

2005 ◽  
Vol 872 ◽  
Author(s):  
Liangjin Wu ◽  
Shanthi Iyer ◽  
Kalyan Nunna ◽  
Sudhakar Bharatan ◽  
Jia Li ◽  
...  
Keyword(s):  
Optical Properties ◽  
Substrate Temperature ◽  
Temperature Dependence ◽  
Growth Parameters ◽  
Blue Shift ◽  
Growth Conditions ◽  
Ex Situ ◽  
Single Quantum Well ◽  
Substrate Temperatures

AbstractIn this paper we report the growth of GaAsSbN/GaAs single quantum well (SQW) heterostructures by molecular beam epitaxy (MBE) and their properties. A systematic study has been carried out to determine the effect of growth conditions, such as the source shutter opening sequence and substrate temperature, on the structural and optical properties of the layers. The substrate temperatures in the range of 450-470 °C were found to be optimal. Simultaneous opening of the source shutters (SS) resulted in N incorporation almost independent of substrate temperature and Sb incorporation higher at lower substrate temperatures.The effects of ex-situ annealing in nitrogen ambient and in-situ annealing under As overpressure on the optical properties of the layers have also been investigated. A significant increase in photoluminescence (PL) intensity with reduced full width at half maxima (FWHM) in conjunction with a blue shift in the emission energy was observed on annealing the samples. In in-situ annealed samples, the PL line shapes were more symmetric and the temperature dependence of the PL peak energy indicated significant decrease in the exciton localization energy as exhibited by a less pronounced “S-shaped curve”. The “inverted S-shaped curve” observed in the temperature dependence of PL FWHM is also discussed. 1.61 μm emission with FWHM of 25 meV at 20K has been obtained in in-situ annealed GaAsSbN/GaAs SQW grown at 470 °C by SS.

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