Nucleation of misfit and threading dislocations during epitaxial growth of GaSb on GaAs(001) substrates

Abstract

The initial stages of molecular beam epitaxy of GaSb on highly mismatched GaAs(001) substrates were investigated. Transmission electron microscopy was used to analyze the defect structure in GaSb islands and at their interfaces with GaAs(001) at different stages of growth. Based on experimental observations, we propose that the semiperiodic net of 90° misfit dislocations at the GaSb/GaAs(001) interface nucleate homogeneously at the leading edges of advancing {111} planes. After nucleation, they glide inwards along the interface plane to reach their equilibrium position. Threading dislocations in GaSb layers were directly correlated with the misfit dislocation net. We demonstrate that there are no threading defects in GaSb islands when their interfaces consist solely of 90° misfit dislocations, and that threading dislocations in the GaSb epilayer are all associated with minority 60° misfit dislocations nucleated in growing islands. The number of threading dislocations per unit area of the GaSb film is found to be independent of GaSb coverage, indicating that island coalescence does not substantially increase the number of 60° dislocations.

p-Type Doping of GaSb by Beryllium Grown on GaAs (001) Substrate by Molecular Beam Epitaxy

“…This consequence confirms that GaSb growth is a Volmer-Weber growth mode [15]. A clear (1×3) RHEED pattern was seen, after few minutes, as it is shown in Fig.…”

Solid solution strengthening in GaSb/GaAs: A mode to reduce the TD density through Be-doping

“…1 The initial strain relief of this highly mismatched island is governed by an IMF array of pure edge 90 MDs along [110] and [1 10] directions located at the GaSb/GaAs interface. Qian et al 21 proposed that 90 MDs at the GaSb/GaAs (001) interface nucleate at the leading edges of advancing {111} planes and glide inward (001) interface during island growth to reach the equilibrium position. Moreover, they do not generate threading dislocations (TDs) inside the islands due to their sessile nature in {111} planes, as shown in Fig.…”

Low-temperature growth of GaSb epilayers on GaAs (001) by molecular beam epitaxy

“…For all the samples, when the Sb shutter was opened, the RHEED pattern changed from a streaky of GaAs (4×2) to bright dots, corresponding to the transfer from a two−dimen− sional (2 D) to a three−dimensional (3 D) growth, being characteristic for Volmer−Weber growth mode [16]. After a few minutes, a clear two−dimensional RHEED (1×3) pat− tern was observed, as it is shown in Fig.…”