Effect of strain on the long-wave infrared emission characteristics of InAs/InxGa1−xAsySb1−y type-Ⅱ superlattices on different substrates

Abstract

Strain influences the optical properties of group III–V type-II superlattice (T2SL) materials. The performance of T2SL photodetectors containing InAs/GaSb is strongly affected by strain. Therefore, it is important to develop novel T2SL material systems and study the stress conditions between their epitaxial layers. Herein, the effect of strain on the long-wave infrared emission characteristics of InAs/In_xGa_1−xAs_ySb_1−y T2SLs on InAs and GaSb substrates was investigated. Free, compressive, and tensile strains were adjusted by precisely controlling the alloy composition and thickness to realize zero, negative, and positive lattice mismatches, respectively, of T2SLs with InAs and GaSb substrates. The InAs/In_xGa_1−xAs_ySb_1−y T2SLs were grown on InAs and GaSb substrates by molecular beam epitaxy and characterized by high-resolution X-ray diffraction, atomic force microscopy, Raman and photoluminescence (PL) measurements. The diffraction and microscopy results indicated that higher crystal quality and better surface morphology were obtained under free strain conditions with zero lattice mismatch on the same type of substrate. Higher crystal quality and better surface morphology were obtained on InAs than GaSb. Power-dependent PL spectra revealed that the luminescence characteristics of the T2SL are dominated by radiative recombination. Temperature-dependent PL spectra showed that the emission intensity of the T2SL on an InAs substrate is greater than that on GaSb. Compared with the T2SLs on GaSb substrates, those on InAs substrates retain strong PL emission intensity at higher temperature under the same strain conditions.