InAsSb quantum dots were grown on GaAs substrates by two methods. One was grown by conventional molecular-beam epitaxy in which arsenic and antimony were irradiated simultaneously. The other was grown by irradiating previously grown InAs dots with antimony to prevent antimony flux from functioning as a surfactant. Although the photoluminescence spectrum of the dots grown by the conventional method had two peaks, the photoluminescence spectrum of the dots grown by the second method had a single peak. Peaks at wavelengths longer than 1.4 µm were observed in the photoluminescence spectrum of the InAsSb quantum dots grown by the second method.