W-shaped InAs/In0.2Ga0.8Sb/InAs/Al0.25Ga0.75As0.08Sb0.92 quantum wells (QWs) have been grown by solid-source molecular beam epitaxy for midinfrared wavelength emission. The tensile strain and the higher As composition in the tensile AlGaAsSb barriers lower the energy level of the heavy holes and increase the hole confinement in the "W" quantum wells, which can improve the temperature properties of the "W" lasers. The tensile-strained Al0.25Ga0.75As0.08Sb0.92 barriers were obtained by growing Al0.25Ga0.75Sb(2 ML)/Al0.25Ga0.75As0.24Sb0.76 (1 ML) digital layers. As evidenced from low-temperature photoluminescence (PL) and x-ray diffraction measurements, the "W" QWs with digitally grown AlGaAsSb barriers show better interface quality and higher PL efficiency than analogous structures with random-alloy AlGaAsSb barriers. Broad-area diode lasers with five-period "W" QWs have been fabricated. A low threshold of 734 A/cm(2) at a lasing wavelength of 3.238 mu m was measured for the 800 mu m X 200 mu m stripe at 153 K. Characteristic temperatures as high as 103 K are achieved in the 80-150 K range. (c) 2005 American Vacuum Society.