M. Tamura et al., THREADING DISLOCATIONS IN GAAS ON SI GROWN WITH SIMILAR-TO-1 NM THICKSI INTERLAYERS, Applied physics. A, Solids and surfaces, 58(2), 1994, pp. 145-155
Threading dislocation morphologies and characteristics have been inves
tigated in 3 mu m thick GaAs films with ultrathin(similar to 1 nm) Si
interlayers grown by molecular beam epitaxy on tilted (2 degrees towar
d [110]Si (001) substrates using cross-sectional transmission electron
microscopy. Four sample structures are studied in which different num
bers of ultrathin Si layers are grown at different positions in the Ga
As film, and the results are compared for samples observed before and
after ex situ annealing. In all of the sample structures, some mixed-t
ype dislocations are clearly blocked by the Si interlayers, although s
ome of them pass through these layers, resulting in propagation of the
ir threading dislocations to the sample surface. After annealing at 90
0 degrees C for 10 s or 800 degrees C for 30 min, the interactions of
the dislocations with the interlayers are enhanced, and there is an in
crease in the number of dislocations which are bent along the [110] di
rections at the positions of the Si barrier layers. However, a conside
rable number of dislocations still escape from the Si barriers by glid
ing on {111} slip planes during annealing. Moreover, ex situ annealing
generates new edge-type dislocations through interactions between mov
ing threading dislocations. The nature of the dislocations that cross
the Si barriers is especially discussed.