Premium
The Relationship between Activation Parameters and Dislocation Glide in 4H‐SiC Single Crystals
Author(s) -
Samant A.V.,
Hong M.H.,
Pirouz P.
Publication year - 2000
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/1521-3951(200011)222:1<75::aid-pssb75>3.0.co;2-0
Subject(s) - materials science , dislocation , stacking fault , crystallography , stacking fault energy , enthalpy , slip (aerodynamics) , atmospheric temperature range , transmission electron microscopy , ribbon , condensed matter physics , stress (linguistics) , composite material , thermodynamics , chemistry , physics , nanotechnology , linguistics , philosophy
4H‐SiC single crystals were deformed by compression in the temperature range 550 to 1300 °C and a strain rate range of 3.1 × 10 –5 to 6.5 × 10 –4 s –1 to determine the critical resolved shear stress for slip on the 〈 2‐1‐10〉(0001) primary slip system. Two different methods to determine the activation parameters for dislocation glide were examined. In the first method, where the activation enthalpy for dislocation glide Δ H g is assumed to be a function of the applied stress τ , Δ H g drops from ∼7.4 eV at τ ≈ 8 MPa to ∼2.8 eV at τ ≈ 235 MPa. In the second method, where the activation enthalpy for dislocation glide, Q , is assumed to be stress‐independent, the values determined at strain rates of less than 6.3 × 10 –5 s –1 were Q ≈ (2.1 ± 0.7) eV at low temperatures ( T < 1100 °C) and Q ≈ (4.5 ± 1.2) eV at high temperatures ( T > 1100 °C). Transmission electron microscopy investigations of the deformed samples show that very different configurations of dislocations are activated under the action of the applied stress. At 1300 °C, the dislocations were all perfect, albeit dissociated into leading/trailing partials separated by a ribbon of stacking fault, while at 700 °C only single leading partials, each dragging a stacking fault and without their corresponding trailing partials, were observed.