M. Calamiotou et al., Microstructural differences of the two possible orientations of GaAs on vicinal (001) Si substrates, J CRYST GR, 227, 2001, pp. 98-103
Two alternative orientations of a GaAs layer in respect to a vicinal (0 0 1
) substrate, misoriented toward [1 1 0], are possible for most of the miscu
t angles; type A orientation having the GaAs [1 1 0] parallel to the [1 1 0
] Si misorientation direction and type B with the GaAs [1 (1) over bar 0] p
arallel to the [1 1 0] Si direction. The dependence of the GaAs surface rou
ghness and of the tilting between the GaAs and Si (0 0 1) planes on the GaA
s/Si orientation and the miscut angle of the vicinal substrate, in the rang
e of 0 9, has been investigated. The GaAs/Si surface roughness was characte
ristic for preferential growth along [1 (1) over bar 0]. Thin GaAs films of
approximately 2 mum thickness exhibited an almost constant rms roughness o
f 6.5-7.0 nm for the type A orientation, while the rms roughness varied in
the range of 4.2-60 nm for the type B orientation, depending on the value o
f the miscut angle. The tilting angle between the GaAs and Si (0 0 1) plane
s exhibited different signs for the two types of orientation and much highe
r values for the type B orientation. A rather constant negative tilting was
observed for type B samples, in the range of miscut angles of 1.-7.5 degre
es. The results suggest that the GaAs/Si lattice tilting may be a sensitive
index for the domain purity in the GaAs/Si films. (C) 2001 Elsevier Scienc
e B.V. All rights reserved.