Low temperature photoluminescence (PL) has been employed to assess the crystalline quality and obtain the band gap energies of (InAs/AlSb/GaSb) 6.2-angstrom-based ternary and quaternary epitaxial layers grown by molecular beam epitaxy. These alloys are employed in low power, high frequency heterojunction bipolar transistors. Strong emission between 0.5 and 1.1 eV attributed to band edge recombination was observed from In0.27Ga0.73Sb and InxAl1-XAsySb1-y layers deposited on both GaSb and GaAs substrates with the best material obtained for substrate temperatures between 350 and 400 degrees C. The PL energies observed for the InAlAsSb epitaxial films are similar to 300 meV less than the band gaps predicted for this system. Most notably, a much higher bowing parameter value (similar to 1.8 eV) is required to model the dependence of the InAlAsSb PL energies on alloy composition.