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Matthews–Blakeslee calculation (Ref. 8) of the critical thickness for InAsSb grown on a GaSb substrate as a function of Sb content. The individual layers of the superlattices discussed here are marked. The inset shows a schematic of the layer structure.
The figure shows the PL spectra for every sample at 4 K. The Sb composition of the InAsSb QWs is denoted. The peak intensity decreases with increasing Sb mole fraction.
The PL peak energies measured at 4 K are plotted as a function of Sb content in the InAsSb QWs. The dotted line is a guide for the eye. Also included are the calculated energy gap of unstrained InAsSb (solid line) and strained on GaSb (dashed line). Further included are the predicted type IIb transition (see inset). Two extreme cases are considered: (a) the alloy band bowing only occurs in the conduction band (dash-dot); (b) the bowing occurs only in the valence band (dash-dot-dot).
Summary of the samples investigated. denotes the layer thickness, while is the average strain per period. A sample schematic is shown in the inset of Fig. 1.
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