Evaluation of stacking faults and associated partial dislocations in AlSb/GaAs (001) interface by aberration-corrected high-resolution transmission electron microscopy

C Wen,J Zhu,Y X Cui,Z Y Cheng,F H Li,R Yu,B H Ge

doi:10.1063/1.4902893

Abstract

The stacking faults (SFs) in an AlSb/GaAs (001) interface were investigated using a 300 kV spherical aberration-corrected high-resolution transmission electron microscope (HRTEM). The structure and strain distribution of the single and intersecting (V-shaped) SFs associated with partial dislocations (PDs) were characterized by the [110] HRTEM images and geometric phase analysis, respectively. In the biaxial strain maps εxx and εyy, a SF can be divided into several sections under different strain states (positive or negative strain values). Furthermore, the strain state for the same section of a SF is in contrast to each other in εxx and εyy strain maps. The modification in the strain states was attributed to the variation in the local atomic displacements for the SF in the AlSb film on the GaAs substrate recorded in the lattice image. Finally, the single SF was found to be bounded by two 30° PDs. A pair of 30° PDs near the heteroepitaxial interface reacted to form a Lomer-Cottrell sessile dislocation located at the vertices of V-shaped SFs with opposite screw components. The roles of misfit dislocations, such as the PDs, in strain relaxation were also discussed.

Highlights

The heteroepitaxial growth of an approximately lattice-matched set ∼6.1 Å (InAs, GaSb, and AlSb) on GaAs substrates covers a wide range of energy gaps at room temperature and offers other properties, providing potential applications in different electronic and optoelectronic devices.1–3 Because the lattice parameter of GaAs is 5.65 Å, the high lattice mismatch (∼8%) between these films and GaAs substrates causes many types of defects in the interface for strain relaxation, such as misfit dislocations (MDs) and stacking faults (SFs)
A pair of 30◦ partial dislocations (PDs) near the heteroepitaxial interface reacted to form a Lomer-Cottrell sessile dislocation located at the vertices of V-shaped SFs with opposite screw components
A pair of 30◦ PDs can react to form a Lomer-Cottrell sessile dislocation located at the vertices of V-shaped SFs if they have opposite screw components,17 such as the pair associated with V2α and V2β

Summary

INTRODUCTION

The heteroepitaxial growth of an approximately lattice-matched set ∼6.1 Å (InAs, GaSb, and AlSb) on GaAs substrates covers a wide range of energy gaps at room temperature and offers other properties, providing potential applications in different electronic and optoelectronic devices. Because the lattice parameter of GaAs is 5.65 Å, the high lattice mismatch (∼8%) between these films and GaAs substrates causes many types of defects in the interface for strain relaxation, such as misfit dislocations (MDs) and stacking faults (SFs). Because the lattice parameter of GaAs is 5.65 Å, the high lattice mismatch (∼8%) between these films and GaAs substrates causes many types of defects in the interface for strain relaxation, such as misfit dislocations (MDs) and stacking faults (SFs) The characteristics of these interfacial defects have attracted much attention and have been investigated using high-resolution transmission electron microscopy/microscope (HRTEM).. The structural characteristics of SFs and the associated PDs have been investigated theoretically and by HRTEM for certain FCC heterostructures, such as ZnSe/GaAs (001), Si/SiGe (001), and 3C-SiC/Si (001).20 These investigations clearly show that large lattice distortions are caused by different types of SFs and extend into large areas of the film, negatively affecting the performance of the devices.. The general results may be applied to other heterostructure systems with large lattice mismatches

EXPERIMENTAL

RESULTS AND DISCUSSION

CONCLUSIONS