Intersubband infrared detector with optimized valence band quantum wells for 3–5 μm wavelength region

We present results on a $p$ -type intersubband infrared detector for the 3–5 μm wavelength region with optimal quantum well design. For valence band quantum wells made by the AlGaAs/GaAs heterosystem with negligible strain, the ground state subband is the first heavy hole subband, and a structure with the second light hole subband in resonance with the top of the barrier is optimal for normal incidence. Using this resonance design, the fabricated detector shows good performance with a background limited operating temperature of 100 K. Our experiments also show a clear polarization dependence for different intersubband transitions involving heavy hole to heavy hole and heavy hole to light hole processes.