Investigation of the asymmetric misfit dislocation morphology in epitaxial layers with the zinc-blende structure

Abstract

Epitaxial growth of compound semiconductors on the (001) exhibits an asymmetry in the dislocation morphology in the two 〈110〉 directions for thicknesses near the critical thickness. The source of the asymmetry has been investigated by growth of a thickness wedge of p- and n-type GaAs0.95 P0.05 on GaAs by metalorganic chemical vapor deposition. The effect of misorientation on the resolved shear stress for each slip system has been calculated and eliminated as the source of the asymmetry. The thickness gradient was also eliminated as the source. A definitive correlation can be made between the asymmetry and the differences in the Peierls barriers of the two types of dislocations. The asymmetry results in two different critical thicknesses, one for each type of dislocation. The Peierls barriers are more similar in p-type material than in n-type material. In agreement with this, a reduced amount of asymmetry was observed in the p-type overgrowth as compared to the n-type. The nucleation barrier differences between the two types of dislocations are shown to be an unlikely source of the asymmetry.

Anisotropic misfit strain relaxation in lattice mismatched InGaAs/GaAs heterostructures grown by MOVPE

“…All the results are in good agreement with the previous reports [8,9] but they contradict the recent one by Yastrubchak et al [10]. This is a result of the p-type doping of the epitaxial layers investigated by the authors of Ref.…”

“…In undoped or n-type doped GaAs-based semiconductor crystals, the a dislocations have a higher glide velocity than b dislocations unlike in p-type crystals, where this sequence is reversed. This difference is characterized by an asymmetry in the formation of both types of dislocations in the /110S directions, resulting in the anisotropic misfit strain relaxation of the epitaxial layer in these directions [4,[8][9][10]. Furthermore, the misorientation of the GaAs substrates from a typical (0 0 1) direction can lead to opposite results in strain relaxation compared with those observed typically for the exactly (0 0 1)-oriented GaAs substrates, as was reported in several papers [4,11].…”

Critical thickness of MBE-grown Ga1−xInxSb (x<0.2) on GaSb

“…One set of layers was grown conventionally with substrate rotation while another set was grown with a method utilizing tilted samples akin to the method used by Fox et al [5]. Fig.…”

Formation energies and equilibrium configurations of dislocation arrays with alternating Burgers vectors in layered heterostructures

“…using appropriate surfactants and substrate off-cuts [8,22,[37][38][39][40]; (2) evolution asymmetry, e.g. using appropriate dopants [41] and asymmetry of dislocation characteristics (Peierls stress or mobility) [22,29,30,[42][43][44][45][46]; (3) thermodynamic asymmetry [47], e.g. using appropriate growth conditions (V/III ratio, surfactants, and temperature [7]) to obtain elongated islands.…”