Normal incidence infrared modulators using intersubband transitions in InAs/GaSb/AlSb stepped quantum wells grown by molecular beam epitaxy

Normal incidence infrared (3–5 μm) modulators based on AlSb/InAs/Al0.4Ga0.6Sb/GaSb/AlSb stepped quantum wells have been successfully grown on (100) GaSb substrates by molecular beam epitaxy. X‐ray diffraction characterization showed sharp satellite peaks. The devices were fabricated and measured using a Fourier transform infrared spectrometer at 77 K. The largest normal incidence infrared absorption coefficient (α) of 3200 cm−1 at 5 μm has been obtained at 14 V applied reverse bias.