Intersubband absorption from 2 to 7 µm in strain-compensated double-barrier InxGa1 xAs multiquantum wells

We report observations of strong room temperature intersubband absorption in strain-compensated In 0.84 Ga 0.16 As/AlAs/In 0.52 Al 0.48 As double-barrier quantum wells grown on InP substrates. Multiple Γ → Γ intersubband transitions have been observed across a wide range of the mid infrared spectrum (2–7 µm) in three structures of differing InGaAs well width (30 Å, 45 Å and 80 Å) and therefore with differing net strain. This absorption range is not covered by direct-gap GaAs/AlGaAs structures.