TEM investigation of the dependence of structural defects on prelayer formation in GaAs-on-Si thin films

We present a transmission electron microscopy (TEM) study of the dependence of structure defects on the kind (Ga or As) and the growth temperature of the prelayer in GaAs-on-Si films grown by molecular beam epitaxy (MBE) on v icinal (100) Si substrates. Generally the prelayer formation conditions do not change the appearance and the density of threading dislocations that re main the main structural defect. However the structural characteristics for each cut-off angle appear to depend eventually on the [011] direction of G aAs epilayer relatively to the [011] misoriented Si substrate direction. Pl anar defects can be avoided only for midrange angles (e.g. 4.5 degrees) usi ng As prelayer at 400 degrees C. (C) 1998 Elsevier Science S.A. All rights reserved.