X-ray rocking curve measurements showed a significant crystallographic
tilt in relaxed InGaAs layer grown on (001) GaAs. Transmission electr
on microscopy revealed that the origin of tilt is 60 degrees dislocati
ons generated having Burgers vectors of a same vertical edge component
. Calculations using anisotropic elasticity show that this configurati
on of 60 degrees dislocation array is energetically favorable when the
tilt of epilayer is present as to remove the long range stress field
induced by the vertical edge components at the interface. (C) 1995 Ame
rican Institute of Physics.