Intersubband quantum well absorption with resonant barriers

The bound-to-extended state interconduction subband absorption and the responsivity in a novel quantum well (QW) structure were calculated. The structure consisted of a quantum well with the addition of two thin barriers just outside of both sides of the well. The effect of the barriers was to create a strong resonant extended state which dramatically improved the sensitivity to infrared radiation. The responsivity due to the absorption from the confined quantum well state into the resonant state was enhanced by more than a factor of four as compared with a quantum well without the extra thin barriers for a 71 Å GaAs/GaAlAs well designed to absorb light with a cutoff wavelength in the 7 μm range. Using this technique we predict that the responsitivities of intersubband transition quantum well detectors can be greatly improved.