Growth and characterization of high-quality GaInAsSb layers on GaSb substrates by liquid-phase epitaxy

High-quality 2.3 μm Ga_1-xIn_xAs_ySb_1-y layers were grown on (100) GaSb substrates by liquid-phase epitaxy using a supercooling technique. The epitaxial layers were characterized by X-ray diffraction, Nomarski-phase contrast microscope, photoluminescence, Fourier transform i.r. and capacitance-voltage measurements. The lattice mismatch normal to the wafer surface between the GaInAsSb layer and GaSb substrate decreases linearly with increasing the mole fraction of As in the growth solution. A mirror-like surface and uniform layer grown on a GaSb substrate is difficult to obtain in the case of a negative lattice mismatch due to strong instability of the solid-liquid interface. The lattice-matched Ga_0.82In_0.18As_0.17Sb_0.83 epitaxial layer grown from the liquidus melt composition of Ga_0.1487In_0.595As_0.0013Sb_0.255 and with a supercooled temperature of 6°C exhibits the narrowest full width at half maximum (FWHM) of 13 meV from a 10-K photoluminescence peak. The bandgap of the lattice-matched quaternary layer is 2.0 μm at 10 K measured by photoluminescence and 2.27 μm at room temperature determined from Fourier transform i.r. measurements. The carrier concentration of 1.2 × 10¹⁶cm^-3 is obtained for this Ga_0.82In_0.18As_0.17Sb_0.83 epitaxial layer by a capacitance-voltage method through a MOS structure and is better than those reported previously.