NSM Archive - Silicon Germanium (SiGe) - Impurities, defects, Dislocation Glide

SiGe - Silicon Germanium

Dislocation Glide

Dislocation glide velocity
v = aσ exp(-Ev/kT) m/s   
, where a 3 x 10-3 m2s/kg;
Ev=2.2 eV 
10 < σ < 100 MPa
Si (x=0); bulk
Hull (1995)
a 3 x 10-3 m2s/kg;
Ev=1.6 eV 
10 < σ < 100 MPa
Ge (x=1); bulk 

To define the glide velocities in strained Si1-xGex layers, normalized glide velocity v* has been introduced:
v*= [vm ·exp(-0.6x/kT)]/σex
This equation normalizes the measured glide velocities vm to an equivalent velocity at an excess stress σex of 1 Pa in pure Si.

v*= exp(-[7.8 + b/kT])    m2/kg   uncapped SiGe;
b = 2 eV:
Hull (1995)
v*= exp(-[10.4 + b/kT])    m2/kg   Si-capped SiGe;
b = 2 eV

Si1-xGex. Normalized dislocation velocities v* for uncapped and capped (0.3 µn, Si) Si1-xGex/Si(001) heterostructures vs. 1/kT
Hull (1995)
Si1-xGex. Measured dislocation propagation velocities vm in Si1-xGex/Si(001) heterostructures vs. excess stress. 550 oC
Hull (1995)