Atomic intermixing and interface roughness in short-period InAs/GaSb superlattices for infrared photodetectors

Abstract

Molecular beam epitaxy growth and characterization of type-II InAs/GaSb strained layer superlattices for longwave infrared detection J. Vac. Sci. Technol. B 28, C3G13 (2010); 10.1116/1.3276429High-performance InAs/GaSb superlattice photodiodes for the very long wavelength infrared range Appl.A set of advanced characterization methods, including high-resolution X-ray diffraction (measurements and simulations), cross-sectional scanning tunneling microscopy, and high-angle annular dark-field scanning transmission electron microscopy is applied to quantify the interface roughness and atomic intermixing (in both cation and anion sub-lattices) in short period (6-7 nm) InAs/GaSb superlattices intended for mid-wavelength (M) and long-wavelength (L) infrared detectors. The undesired atomic intermixing and interface roughness in the L-samples were found to be considerably lower than in the M-samples. In all specimens, anion intermixing is much higher than that in the cation sub-lattice. Possible origins of these findings are discussed. V C 2014 AIP Publishing LLC.

Measurement of Diffusion and Segregation in Semiconductor Quantum Dots and Quantum Wells by Transmission Electron Microscopy: A Guide

“…If the specimen is of constant thickness and only two elements can interdiffuse, i.e., in binary systems such as SiGe, or in a quasi-binary systems such as ternary InGaAs or AlGaN (where one sub-lattice is fixed), then changes of the scattering intensity can be directly interpreted in terms of chemistry. For quaternary systems, where several atomic species can interdiffuse, e.g., Al x Ga y In 1-x-y As, Ga x In 1-x- As y Sb 1-y , direct spectroscopic studies are generally needed unless atomic sub-lattices can be imaged independently [4]. The same applies to co-segregation of several chemical elements, such as of Tb and O in Tb-doped AlN [5].…”

Molecular beam epitaxy of interband cascade structures with InAs/GaSb superlattice absorbers for long-wavelength infrared detection

“…For group-V rich conditions, one might expect InAs-on-GaSb and GaSb-on-InAs to naturally form interfaces that are InSb-like and GaAs-like, respectively. In reality, the interface formation can be complicated by the segregation and intermixing of atoms in those layers, which can be influenced through different methods [4,10,13,21,24,26]. A naturally formed GaSb-on-InAs interface has been confirmed to be GaAs-like by Krishnamurthy et al [22].…”