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.

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.

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.

Real-Time Measurement of the Evolution of Growth Facets during SiC PVT Bulk Growth Using 3-D X-Ray Computed Tomography

2014 ◽  
Vol 778-780 ◽  
pp. 9-12 ◽  
Author(s):  
Georg Neubauer ◽  
Michael Salamon ◽  
Norman Uhlmann ◽  
Peter J. Wellmann
Keyword(s):  
Computed Tomography ◽  
Real Time ◽  
High Precision ◽  
Growth Interface ◽  
X Ray ◽  
Bulk Growth ◽  
Real Time Measurement ◽  
Growth System ◽  
X Ray Computed

In this paper, we present our new setup and technique for obtaining a real-time 3-D volume shape of the SiC crystal using X-ray computed tomography (CT). Hence, it is possible to determine in-situ the shape of the growth interface with high precision at growth temperatures above 2000 °C in a conventional 3" physical vapor transport (PVT) growth system. We show that the size and shape of a facet can be monitored at different stages during growth and furthermore the crystals face boundary can be determined with high precision throughout the whole growth process.

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.

Application of 3-D X-Ray Computed Tomography for the In Situ Visualization of the SiC Crystal Growth Interface during PVT Bulk Growth

2013 ◽  
Vol 740-742 ◽  
pp. 27-30 ◽  
Author(s):  
Georg Neubauer ◽  
Michael Salamon ◽  
Florian Roider ◽  
Norman Uhlmann ◽  
Peter J. Wellmann
Keyword(s):  
Computed Tomography ◽  
Crystal Growth ◽  
Vapor Transport ◽  
Growth Interface ◽  
X Ray ◽  
Bulk Growth ◽  
Growth System ◽  
X Ray Computed ◽  
First Time

In this paper, we present for the first time an in-situ 3-D reconstruction of the SiC crystal growth interface using X-ray computed tomography (CT). We show that the shape of the growth interface can be determined with high precision at growth temperatures above 2100 °C in a conventional 3” PVT (physical vapor transport) growth system.

In-situ X-ray Computed Tomography Analysis of Fracture Mechanisms in Ultrasonic Additively Manufactured Al-6061 Alloy

2021 ◽  
pp. 102401
Author(s):  
Ercan Cakmak ◽  
Maxim N. Gussev ◽  
Thomas R. Watkins ◽  
David J. Arregui-Mena ◽  
Kurt A. Terrani
Keyword(s):  
Computed Tomography ◽  
Fracture Mechanisms ◽  
X Ray ◽  
Al 6061 ◽  
X Ray Computed ◽  
Tomography Analysis

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.

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.

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