Interaction Between Recombination Enhanced Dislocation Glide Process Activated Basal Stacking Faults and Threading Dislo
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0994-F12-03
Interaction Between Recombination Enhanced Dislocation Glide Process Activated Basal Stacking Faults and Threading Dislocations in 4H-Silicon Carbide Epitaxial Layers
Yi Chen1, Michael Dudley1, Kendrick X. Liu2, and Robert E. Stahlbush2 1
Materials Science and Engineering, Stony Brook University, Stony Brook, NY, 11794-2275
2
Naval Research Laboratory, Washington, DC, 20375-5320
ABSTRACT Electron-hole recombination enhanced glide of Shockley partial dislocations bounding expanding stacking faults and their interactions with threading dislocations in 4H silicon carbide epitaxial layers have been studied using synchrotron white beam X-ray topography and in situ electroluminescence. The mobile silicon-core Shockley partial dislocations bounding the stacking faults are able to cut through threading edge dislocations leaving no trailing dislocation segments in their wake. However, when the Shockley partial dislocations interact with threading screw dislocations, trailing 30o partial dislocation dipoles are initially deposited in their wake due to the pinning effect of the threading screw dislocations. These dipoles spontaneously snap into their screw orientation, regardless the normally immobile carbon-core Shockley partial dislocation components in the dipoles. The subsequent cross slip and annihilation of screw oriented Shockley partial dipole leave a prismatic stacking fault in (2-1-10) plane with the displacement vector 1/3[01-10]. The formation of such prismatic stacking fault is energetically favorable, reducing the strain energy by one to two orders of magnitude. INTRODUCTION Various defects including micropipes (MPs), triangular defects, stacking faults (SFs) and low angle grain boundaries (LAGBs), have been found to deteriorate the device performance made from 4H-silicon carbide (SiC) [1]. The basal SFs in SiC are bounded by Shockley partial dislocations (PDs) which are dissociated from the perfect basal plane dislocations (BPDs). The forward voltage drop observed in SiC bipolar devices under forward biasing has been attributed to the expansion of such basal SFs [2]. The Si-core PD is found to be mobile while the carbon-core (C-core) PD is stationary. As these advancing Shockley PDs, activated by recombination enhanced dislocation glide (REDG) process, encounter a forest of threading dislocations (TDs) in the SiC crystals, including threading edge dislocations (TEDs) (104~105/cm2) and threading screw dislocations (TSDs) (103~104/cm2), various interactions are expected. Understanding these interactions can provide further insight into the nature of the electron-hole recombination activated defect reaction and may shed light on strategies designed to mitigate their deleterious effects. EXPERIMENTAL Electron-hole recombination activated expansion of SFs and their interaction with TDs were
studied using in situ electroluminescence (EL) and synchrotron white beam X-ray topography (SWBXT). The 4H-SiC substrate used in this study were commercially available wafers grown by physical vapor transport (
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