Abstract
This work provides a detailed study on the growth of AlxIn1-xAsySb1-y lattice-matched to InAs by Molecular Beam Epitaxy. In order to find the conditions which lead to high crystal quality deep within the miscibility gap, AlxIn1-xAsySb1-y with x = 0.462 was grown at different growth temperatures as well as As2 and Sb2 beam equivalent pressures. The crystal quality of the grown layers was examined by high-resolution X-ray diffraction and atomic force microscopy. It was found that the incorporation of Sb into Al0.462In0.538AsySb1-y is strongly temperature-dependent and reduced growth temperatures are necessary in order to achieve significant Sb mole fractions in the grown layers. At 480 ∘ C lattice matching to InAs could not be achieved. At 410 ∘ C lattice matching was possible and high quality films of Al0.462In0.538AsySb1-y were obtained.
Highlights
InAs is an interesting material for inter-subband devices such as quantum cascade lasers (QCLs) due to its low effective mass, since it is expected to enable higher performance by providing higher gain [1]
The data presented in this study suggests that a Tg of 445 ◦ C is the upper limit for lattice matched growth of Al0.462 In0.538 Asy Sb1-y
We investigated the growth of Al0.462 In0.538 Asy Sb1-y
Summary
InAs is an interesting material for inter-subband devices such as quantum cascade lasers (QCLs) due to its low effective mass, since it is expected to enable higher performance by providing higher gain [1]. The commonly used Al(As)Sb material, though enabling excellent results for mid-infrared (MIR) devices [2,3,4,5], requires the use of monolayer and sub-monolayer thin barriers for devices designed to emit in the terahertz (THz) regime, due to its very high conduction band offset The growth of such thin layers is very difficult to control, and to date, no THz laser operation has been shown. The authors report a high dislocation density, found in a transmission electron microscopy study of the grown material, resulting from the highly lattice-mismatched conditions It is questionable whether this result is applicable to the growth of Alx In1-x Asy Sb1-y on InAs. Wahsington-Stokes et al [10] report on the growth of Alx In1-x Asy Sb1-y with an As mole fraction between 0.37 and 0.72 at a Tg between 355 ◦ C and 378 ◦ C on GaSb substrates and report good crystal quality for the grown layers. The influence of the Sb and As beam equivalent pressures (BEP) or the Tg on the quality and composition of the layers is not mentioned
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