Peak separation method for sub-lattice strain analysis at atomic resolution: Application to InAs/GaSb superlattice

Abstract

We report on a direct measurement of cation and anion sub-lattice strain in an InAs/GaSb type-II strained layer superlattice (T2SLs) using atomic resolution Z-contrast imaging and advanced image processing. Atomic column positions in InAs and GaSb are determined by separating the cation and anion peak intensities. Analysis of the InAs/GaSb T2SLs reveals the compressive strain in the nominal GaSb layer and tensile strain at interfaces between constituent layers, which indicate In incorporation into the nominal GaSb layer and the formation of GaAs like interfaces, respectively. The results are compared with the model-dependent X-ray diffraction measurements in terms of interfacial chemical intermixing and strain.

Strategy for reliable strain measurement in InAs/GaAs materials from high-resolution Z-contrast STEM images

“…3 demonstrates. While the approach used by GPA is advantageous for the analysis of HRTEM images of limited spatial resolution, ideally, the analysis of aberration corrected STEM images should take the advantages of all frequencies, and this can be achieved using real space based methods based on atomic peak finding or template matching (TeMA) [5,6]. In these methods, the position of the atomic columns is determined by the intensity distribution, which utilizes all information recorded in the image.…”

Determination of atomic vacancies in InAs/GaSb strained-layer superlattices by atomic strain

“…atomic columns is close ($1.5 Å ), the intensities of the atomic columns overlap, which makes the precise determination of the atomic column positions difficult (Peters et al, 2015). To overcome this issue, we have recently developed a peak separation method (Kim, Meng, Rouvié re & Zuo, 2017). The method uses Gaussian peak fitting to construct two fitted images of the cations and anions.…”

“…The method enables the separation of strain due to composition from that caused by defects. The strain analysis is performed on the anion and cation sublattices at a high spatial resolution using the method described by Kim, Meng, Rouvié re & Zuo (2017).…”

A new method to reliably determine elastic strain of various crystal structures from atomic-resolution images

“…Nowadays, PP works well on all the highly symmetrical crystal systems, such as Ge/Si 25 , InAs/GaAs 16 , InAs/GaSb 26,27 and AlSb/GaAs 28 to study the strain field at the heterogeneous interface. One common characteristic of these material systems are either face-centered-cubic (FCC) or body-centered-cubic (BCC) structures.…”