Basal Plane Dislocation Dynamics in Highly p-Type Doped versus Highly n-Type Doped SiC

2006 ◽  
pp. 79-82
Author(s):  
Peter J. Wellmann ◽  
Desirée Queren ◽  
Ralf Müller ◽  
Sakwe Aloysius Sakwe ◽  
Ulrike Künecke
Keyword(s):  
Basal Plane ◽  
Dislocation Dynamics ◽  
Basal Plane Dislocation ◽  
P Type

Basal Plane Dislocation Dynamics in Highly p-Type Doped versus Highly n-Type Doped SiC

2006 ◽  
Vol 527-529 ◽  
pp. 79-82 ◽  
Author(s):  
Peter J. Wellmann ◽  
Desirée Queren ◽  
Ralf Müller ◽  
Sakwe Aloysius Sakwe ◽  
Ulrike Künecke
Keyword(s):  
Basal Plane ◽  
Stacking Fault ◽  
Dislocation Dynamics ◽  
Dislocation Generation ◽  
Basal Plane Dislocation ◽  
Substrate Wafer ◽  
P Type ◽  
Long Term Performance ◽  
Term Performance

The long term performance of today’s SiC based bipolar power devices suffer strongly from stacking fault formation caused by slip of basal plane dislocations, the latter often originating from the n-type doped SiC substrate wafer. In this paper, using sequentially p-type / n-type / p-type doped SiC crystals, we address the question, whether basal plane dislocation generation and annihilation behaves differently in n-type and p-type SiC. We have found that basal plane dislocations are absent or at least appear significantly less pronounced in p-type doped SiC, which may become of great importance for the stacking fault problem in SiC.

Impact of n-Type versus p-Type Doping on Mechanical Properties and Dislocation Evolution during SiC Crystal Growth

2007 ◽  
Vol 556-557 ◽  
pp. 259-262 ◽  
Author(s):  
Peter J. Wellmann ◽  
Philip Hens ◽  
Sakwe Aloysius Sakwe ◽  
Desirée Queren ◽  
Ralf Müller ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Crystal Growth ◽  
Dislocation Density ◽  
Basal Plane ◽  
Critical Shear Stress ◽  
Lattice Relaxation ◽  
Dislocation Generation ◽  
Basal Plane Dislocation ◽  
Donor Nitrogen ◽  
P Type

The origin of dislocation evolution during SiC crystal growth is usually related to lattice relaxation mechanisms caused by thermal stress. In this paper we discuss dislocation generation and dislocation propagation related to doping and suppression of basal plane dislocations, the latter being of particular interest for bipolar electronic devices. We have prepared alternating p-/n-/pdoped SiC crystals using the donor nitrogen and the acceptors aluminum or boron. In addition we determined the mechanical properties of n-type and p-type SiC; in particular we measured the critical shear stress by nano-indentation on c-plane and a-plane 6H-SiC surfaces. A considerably lower basal plane dislocation density is found in aluminum as well as in boron doped p-type SiC compared to nitrogen doped n-type SiC. It is concluded that the explanation of the reduced basal plane dislocation density in p-type SiC needs the consideration of electronic as well as mechanical effects.

Analysis of Basal Plane Dislocation Dynamics in 4H-SiC Crystals during High Temperature Treatment

2019 ◽  
Vol 963 ◽  
pp. 268-271
Author(s):  
Balaji Raghothamachar ◽  
Yu Yang ◽  
Jian Qiu Guo ◽  
Michael Dudley
Keyword(s):  
High Temperature ◽  
Basal Plane ◽  
Dislocation Motion ◽  
Temperature Treatment ◽  
Dislocation Dynamics ◽  
High Temperature Treatment ◽  
Velocity Measurements ◽  
Basal Plane Dislocation ◽  
Induced Motion

Direct observation of thermal gradient induced motion of basal plane dislocations by in-situ synchrotron X-ray topography imaging of PVT-grown 4H-SiC wafers subject to high temperature treatment has provided an opportunity to analyze the movement of dislocations. Dislocations with Burgers vector along the off-cut [11-20] direction were found to be the only dislocations involved in deformation during heat treatment and the segments of dislocations used for velocity measurements were found to be either pure screw comprised of both Si-and C-core partials or 60° dislocations comprised of purely Si cores. Using the kink-diffusion model, the activation energies for dislocation motion have been calculated from the velocity data for each of these dislocation types and found to be 3.28eV for pure screw and 2.21eV for 60° dislocation segments, respectively.

The stability of dislocation networks under various oxygen-doping conditions in superconducting Bi2Sr2CaCu2Oy single crystals and their influence on the flux pinning properties

1994 ◽  
Vol 52 ◽  
pp. 802-803
Author(s):  
Y. Feng ◽  
X. Y. Cai ◽  
R. J. Kelley ◽  
D. C. Larbalestier
Keyword(s):  
Single Crystals ◽  
Oxygen Content ◽  
Basal Plane ◽  
Flux Pinning ◽  
Pinning Centers ◽  
Before And After ◽  
Anomalous Peak ◽  
Basal Plane Dislocation ◽  
The Stability ◽  
Further Development

The issue of strong flux pinning is crucial to the further development of high critical current density Bi-Sr-Ca-Cu-O (BSCCO) superconductors in conductor-like applications, yet the pinning mechanisms are still much debated. Anomalous peaks in the M-H (magnetization vs. magnetic field) loops are commonly observed in Bi2Sr2CaCu2Oy (Bi-2212) single crystals. Oxygen vacancies may be effective flux pinning centers in BSCCO, as has been found in YBCO. However, it has also been proposed that basal-plane dislocation networks also act as effective pinning centers. Yang et al. proposed that the characteristic scale of the basal-plane dislocation networksmay strongly depend on oxygen content and the anomalous peak in the M-H loop at ˜20-30K may be due tothe flux pinning of decoupled two-dimensional pancake vortices by the dislocation networks. In light of this, we have performed an insitu observation on the dislocation networks precisely at the same region before and after annealing in air, vacuumand oxygen, in order to verify whether the dislocation networks change with varying oxygen content Inall cases, we have not found any noticeable changes in dislocation structure, regardless of the drastic changes in Tc and the anomalous magnetization. Therefore, it does not appear that the anomalous peak in the M-H loops is controlled by the basal-plane dislocation networks.

The Effect of Doping Concentration and Conductivity Type on Preferential Etching of 4H-SiC by Molten KOH

2004 ◽  
Vol 815 ◽  
Author(s):  
Ying Gao ◽  
Zehong Zhang ◽  
Robert Bondokov ◽  
Stanislav Soloviev ◽  
Tangali Sudarshan
Keyword(s):  
Thermal Diffusion ◽  
Basal Plane ◽  
Doping Concentration ◽  
Structural Defects ◽  
Etch Pits ◽  
Conductivity Type ◽  
Isotropic Etching ◽  
Electrochemical Processes ◽  
P Type ◽  
Koh Etching

AbstractMolten KOH etchings were implemented to delineate structural defects in the n- and ptype 4H-SiC samples with different doping concentrations. It was observed that the etch preference is significantly influenced by both the doping concentrations and the conductivity types. The p-type Si-face 4H-SiC substrate has the most preferential etching property, while it is least for n+ samples. It has been clearly demonstrated that the molten KOH etching process involves both chemical and electrochemical processes, during which isotropic etching and preferential etching are competitive. The n+ 4H-SiC substrate was overcompensated via thermal diffusion of boron to p-type and followed by molten KOH etching. Three kinds of etch pits corresponding to threading screw, threading edge, and basal plane dislocations are distinguishably revealed. The same approach was also successfully employed in delineating structural defects in (0001) C-face SiC wafers.

Do You Really Expect To Grow Epilayers On That? A Rationale For Growing Epilayers On Roughened Surfaces

2006 ◽  
Vol 911 ◽  
Author(s):  
Joseph John Sumakeris ◽  
Brett A. Hull ◽  
Michael J. O'Loughlin ◽  
S. Ha ◽  
Marek Skowronski ◽  
...  
Keyword(s):  
Basal Plane ◽  
Substrate Surface ◽  
Surface Preparation ◽  
Processing Parameters ◽  
Optimal Process ◽  
Device Structure ◽  
Process Route ◽  
Basal Plane Dislocation ◽  
Vf Drift ◽  
Edge Dislocations

AbstractWe describe surface preparation and epilayer growth techniques that readily reduce the density of Vf drift inducing basal plane dislocations in epilayers to less than 10 cm-2 and permit the fabrication of bipolar SiC devices with very good Vf stability. The optimal process route requires etching the substrate surface prior to epilayer growth to enhance the natural conversion of basal plane dislocations into threading edge dislocations during epilayer growth. The surface of this relatively rough “conversion” epilayer is subsequently repolished prior to growing the device structure. We provide details on processing parameters and potential problems as well as describe devices produced using this low basal plane dislocation growth processes.

Defects and Polytype Instabilities

2018 ◽  
Vol 924 ◽  
pp. 147-150
Author(s):  
Jörg Pezoldt ◽  
Andrei Alexandrovich Kalnin
Keyword(s):  
Long Range ◽  
Basal Plane ◽  
Partial Dislocation ◽  
Stacking Faults ◽  
Dislocation Loops ◽  
Elastic Fields ◽  
Basal Plane Dislocation ◽  
The Stability ◽  
Shockley Dislocation ◽  
Polytype Structure

A model based on the generation and recombination of defect was developed to describe the stability of stacking faults and basal plane dislocation loops in crystals with layered polytype structures. The stability of the defects configuration was analysed for stacking faults surrounded by Shockley and Frank partial dislocation as well as Shockley dislocation dipoles with long range elastic fields. This approach allows the qualitative prediction of defect subsystems in polytype structure in external fields.

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