Molecular beam epitaxy of AlInAsSb alloys near the miscibility gap boundary

AlxIn1−xAsySb1−y alloys lattice matched to InAs with an Al content up to x=0.25 have been grown by molecular beam epitaxy on InAs (0 0 1) substrates and studied by double-crystal X-ray diffraction, scanning electron microscopy and photoluminescence (PL) spectroscopy. Thermodynamic stability of these alloys at typical MBE temperatures has been revised. It has been found that AlInAsSb alloys with x∼0.15, grown at temperatures below 470 °C, exhibit spinodal decomposition in good agreement with the calculated chemical instability gap boundary. However, the alloys with x∼0.2 grown at higher temperature (above 500 °C) have exhibited no decomposition features and demonstrate bright PL at 80 K.