Application of In Situ 3D Computed Tomography during PVT Growth of 4H-SiC for the Study of Source Material Consumption under Varying Growth Conditions

2016 ◽  
Vol 858 ◽  
pp. 49-52 ◽  
Author(s):  
P.J. Wellmann ◽  
Lars Fahlbusch ◽  
Michael Salamon ◽  
Norman Uhlmann
Keyword(s):  
Growth Parameters ◽  
Growth Conditions ◽  
Source Material ◽  
Gas Pressure ◽  
Inert Gas ◽  
Material Surface ◽  
Growth Interface ◽  
Axial Temperature ◽  
The Stability

2D and 3D in-situ X-ray visualization was applied to study the behavior of the SiC source material during PVT growth under various growth conditions. Experiments were carried out in two growth chambers for the growth of 3 inch and 4 inch crystals. Growth parameters were varied in the gas room in terms of axial temperature and inert gas pressure. The study addresses the stability of the SiC source material surface. It is shown that a higher inert gas pressure (e.g. 25 mbar) inhibits an unintentional upward evolution of the SiC feedstock that interferes with the crystal growth interface. The latter is related to a suppression of a pronounced recrystallization inside the SiC source. For a low inert gas pressure (e.g. 10 mbar) it is concluded that the axial temperature gradient inside the source material needs to be decreased to less than ca. 10 K/cm.

scholarly journals Optimization of the SiC Powder Source Material for Improved Process Conditions During PVT Growth of SiC Boules

Materials ◽  
2019 ◽  
Vol 12 (19) ◽  
pp. 3272
Author(s):  
Ellefsen ◽  
Arzig ◽  
Steiner ◽  
Wellmann ◽  
Runde
Keyword(s):  
Crystal Growth ◽  
Size Distribution ◽  
Growth Conditions ◽  
Source Material ◽  
Process Time ◽  
Process Conditions ◽  
Powder Size ◽  
Growth Interface ◽  
X Ray

We have studied the influence of different SiC powder size distributions and the sublimation behavior during physical vapor transport growth of SiC in a 75 mm and 100 mm crystal processing configuration. The evolution of the source material as well as of the crystal growth interface was carried out using in situ 3D X-ray computed tomography (75 mm crystals) and in situ 2D X-ray visualization (100 mm crystals). Beside the SiC powder size distribution, the source materials differed in the maximum packaging density and thermal properties. In this latter case of the highest packaging density, the in situ X-ray studies revealed an improved growth interface stability that enabled a much longer crystal growth process. During process time, the sublimation-recrystallization behavior showed a much smoother morphology change and slower materials consumption, as well as a much more stable shape of the growth interface than in the cases of the less dense SiC source. By adapting the size distribution of the SiC source material we achieved to significantly enhance stable growth conditions.

Growth Conditions and In Situ Computed Tomography Analysis of Facetted Bulk Growth of SiC Boules

2018 ◽  
Vol 924 ◽  
pp. 245-248
Author(s):  
Matthias Arzig ◽  
Michael Salamon ◽  
Norman Uhlmann ◽  
Bertil A. Johansen ◽  
Peter J. Wellmann
Keyword(s):  
Computed Tomography ◽  
Packing Density ◽  
Thermal Gradient ◽  
Growth Conditions ◽  
Source Material ◽  
Lateral Growth ◽  
Growth Interface ◽  
Bulk Growth ◽  
Tomography Analysis

Two 3inch SiC boules were grown in a PVT setup using source material of different packing density. During the growth, in-situ computed tomography of the growing boules showed differences in the development of the growth interface. A slightly bent growth interface was found for the smaller packing density. For the higher packing density the resulting crystal exhibits the onset of 6 pyramidal facets on its flanks. Besides that, strong anisotropic lateral growth was found on its (000-1) facet. Numerical simulations show an impact of the powder on the thermal gradient in the growth cell and therefore on the supersaturation. It is discussed that a higher supersaturation can account for the anisotropy in the growth rate of the [1-100] and the [11-20] direction.

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.

Studies of the growth parameters for silver nanoparticle synthesis by inert gas condensation

2007 ◽  
Vol 22 (12) ◽  
pp. 3378-3384 ◽  
Author(s):  
M. Raffi ◽  
Abdul K. Rumaiz ◽  
M.M. Hasan ◽  
S. Ismat Shah
Keyword(s):  
Silver Nanoparticles ◽  
Theoretical Model ◽  
Growth Parameters ◽  
Nanoparticle Synthesis ◽  
Spherical Shape ◽  
Gas Pressure ◽  
Inert Gas ◽  
Gas Condensation ◽  
Evaporation Temperature ◽  
Inert Gas Condensation

Silver nanoparticles were synthesized by an inert gas condensation method using flowing helium in the process chamber. Nucleation, growth mechanism, and the kinetics of nanoparticle formation in vapor phase are studied. Effect of process parameters, such as evaporation temperature and inert gas pressure, on the particle crystallinity, morphology, and size distribution are examined. Particles were synthesized at evaporation temperatures of 1123, 1273, and 1423 K and at helium pressures of 0.5, 1, 5, 50, and 100 Torr. Synthesized silver nanoparticles were characterized by x-ray diffraction (XRD) and transmission electron microscopy (TEM). The particle size ranged from 9 to 32 nm, depending on the growth conditions. At lower evaporation temperature and inert gas pressure, smaller particles with spherical shape showing less agglomeration are formed. Based on the experimental results and theoretical model of surface free energy and undercooling as a function of evaporation temperature and inert gas pressure, particle formation is analyzed. A simple operating map for nanoparticle synthesis is presented. The theoretical model is well supported by the experimental data.

Optimization of the SiC Powder Source Size Distribution for the Sublimation Growth of Long Crystals Boules

2019 ◽  
Vol 963 ◽  
pp. 42-45
Author(s):  
Johannes Steiner ◽  
Matthias Arzig ◽  
Ta Ching Hsiao ◽  
Peter J. Wellmann
Keyword(s):  
Size Distribution ◽  
Shape Change ◽  
Growth Conditions ◽  
Powder Size ◽  
Growth Interface ◽  
Morphology Change ◽  
Powder Density ◽  
Stable Growth ◽  
Sublimation Growth

The influence of four different SiC source powder size distributions on the sublimation behavior during physical vapor transport growth of SiC was studied. The growth processes were carried out in a 3 inch crystal growth setup and observed in situ using advanced 3D computed tomography X-ray visualization. The single modal D90 size distribution of two source powders was 50 μm and 200 μm, respectively, with a corresponding average powder density of 1.17 g/cm3. The third source powder consisted of a blend of the previously named powders and exhibited an average powder density of 1.66 g/cm3 with a bimodal particle size distribution. The last source was composed of a solid polycrystalline SiC cylinder. The bimodal powder source exhibited a smoother morphology change and material consumption during the growth run and led to a much more stable shape change of the growth interface compared to the single modal source powders. The solid source featured the least morphology change. Therefore, with a careful adaption of the source material stable growth conditions can be achieved.

Growth Conditions of Erbium-Oxygen-Doped Silicon Grown by MBE

1996 ◽  
Vol 422 ◽  
Author(s):  
J. Stimmer ◽  
A. Reittinger ◽  
G. Abstreiter ◽  
H. Holzbrecher ◽  
Ch. Buchal
Keyword(s):  
Molecular Beam Epitaxy ◽  
Systematic Study ◽  
Molecular Beam ◽  
Growth Parameters ◽  
Light Emitting Diode ◽  
Growth Conditions ◽  
Light Emitting ◽  
Doped Silicon

AbstractWe report on a systematic study of the growth parameters of erbium-oxygen-doped silicon grown by molecular beam epitaxy. The surface quality of the grown layers was measured in situ by RHEED. The samples were characterized by photoluminescence measurements and SIMS. An Er-O-doped Si light emitting diode grown with the optimized parameters is presented.

scholarly journals Influence of Morphological Changes in a Source Material on the Growth Interface of 4H-SiC Single Crystals

Materials ◽  
2019 ◽  
Vol 12 (16) ◽  
pp. 2591 ◽  
Author(s):  
Matthias Arzig ◽  
Johannes Steiner ◽  
Michael Salamon ◽  
Norman Uhlmann ◽  
Peter J. Wellmann
Keyword(s):  
Thermal Conductivity ◽  
Morphological Changes ◽  
Laser Flash ◽  
Source Material ◽  
Ex Situ ◽  
Growth Interface ◽  
Bulk Growth ◽  
Before And After ◽  
Conductivity Models

In this study, the change of mass distribution in a source material is tracked using an in situ computer tomography (CT) setup during the bulk growth of 4H- silicon carbide (SiC) via physical vapor depostion (PVT). The changing properties of the source material due to recrystallization and densification are evaluated. Laser flash measurement showed that the thermal properties of different regions of the source material change significantly before and after the growth run. The Si-depleted area at the bottom of the crucible is thermally insulating, while the residual SiC source showed increased thermal conductivity compared to the initially charged powder. Ex situ CT measurements revealed a needle-like structure with elongated pores causing anisotropic behavior for the heat conductivity. Models to assess the thermal conductivity are applied in order to calculate the changes in the temperature field in the crucible and the changes in growth kinetics are discussed.

Prospects of Bulk Growth of 3C-SiC Using Sublimation Growth

2020 ◽  
Vol 1004 ◽  
pp. 113-119
Author(s):  
Peter J. Wellmann ◽  
Philipp Schuh ◽  
Manuel Kollmuss ◽  
Michael Schöler ◽  
Johannes Steiner ◽  
...  
Keyword(s):  
Bulk Material ◽  
Growth Conditions ◽  
Free Standing ◽  
Growth Interface ◽  
Seed Transfer ◽  
Bulk Growth ◽  
Axial Temperature ◽  
High Supersaturation ◽  
Proper Design ◽  
Stable Growth

Free standing 3C-SiC wafers with a dimeter of 50 mm and a thickness of ca. 0.8 mm have been grown on a regular base using 3C-SiC CVD seed transfer from Si wafers to a poly-SiC-carrier and a sublimation epitaxy configuration. Up to the thickness of almost 1 mm, stable growth conditions of the cubic polytype have been achieved. The high supersaturation was kept stable by the proper design of the hot zone that enables a high axial temperature gradient at the growth interface. The Sirich gas phase was realized by the application of a Tantalum getter that was integrated into the graphitebased growth cell. Furthermore, an adaption of the growth setup allowed the growth of 3C material with a diameter of 95 mm and bulk material up to 3 mm on 25 mm diameter. Computer simulations were used to determine the supersaturation of the growth setup for different source-to-seed distances. The minimum supersaturation necessary for stable growth of cubic SiC was found to be higher 0.1 for seed already containing the required 3C polytype.

Investigation of Run-to-Run Fluctuation in Growth Conditions of Physical Vapor Transport Growth of 4H-SiC Crystals

2018 ◽  
Vol 924 ◽  
pp. 19-22
Author(s):  
Nana Matsumoto ◽  
Hiroaki Shinya ◽  
Koji Ashida ◽  
Tadaaki Kaneko ◽  
Noboru Ohtani ◽  
...  
Keyword(s):  
Surface Morphology ◽  
Surface Properties ◽  
Growth Parameters ◽  
Growth Conditions ◽  
Source Material ◽  
Vapor Transport ◽  
Physical Vapor Transport ◽  
Major Parameter ◽  
Surface Morphologies

We investigated the run-to-run fluctuation in growth conditions of physical vapor transport growth of 4H-SiC boules through observations of surface morphology on the (000-1) facet of the boules. The boules, which were grown under the same macroscopic growth conditions, exhibited slightly different surface morphologies. This indicates that some microscopic growth parameters that influence the surface morphology fluctuate between growth runs. We have considered the C/Si ratio of the vapor sublimed from the source material as a major parameter and discussed the associated variations in the physical and surface properties of the grown crystals.

Study of MBE ZnSe Growth Using Rheed Oscillations

1989 ◽  
Vol 145 ◽  
Author(s):  
Francoise S. Turco ◽  
M.C. Tamargo
Keyword(s):  
Growth Rate ◽  
Quantitative Study ◽  
Growth Parameters ◽  
Growth Conditions ◽  
High Energy ◽  
Growth Mechanisms ◽  
Mbe Growth ◽  
Wide Range ◽  
Main Growth

AbstractReflection high energy electron diffraction (RHEED) intensity oscillations are often used to investigate in situ the growth of III-V materials by molecular beam epitaxy (MBE). In this work, we have used RHEED oscillations to perform a quantitative study of the growth mechanisms of ZnSe, a II-VI semiconductor.Our experiments illustrate that the RHEED pattern of ZnSe is far less intense than that of III-V materials grown by MBE, and no specular spot is observed over a wide range of growth conditions. We have, however, been able to record up to 25 oscillations allowing a quantitative study of the growth of ZnSe by MBE. Thus we have used RHEED oscillations to make an in situ systematic study of the influence of the three main growth parameters (substrate temperature and Zn or Se impinging fluxes) on the ZnSe growth rate. We observed that the variation of the ZnSe growth rate is due to a non unity sticking coefficient of both Zn and Se species at the interface in the standard growth conditions used. Our observations can be described using a thermodynamic model and enable us to control the desired growth conditions. Our work demonstrates the utility of RHEED oscillations to understand the MBE growth mechanisms of II-VI compounds.

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