Broadening of the absorption spectrum in a p-type InGaAs - InAlAs coupled quantum well

The intervalence subband absorption of normally incident infrared radiation in a p-type InGaAs - InAlAs coupled quantum well (CQW) is theoretically investigated by the multiband effective mass formalism. We calculate valence subband structures, intervalence subband transition matrix elements and the absorption coefficient spectrum in the CQW which consists of a wider well, a thinner well and a barrier between. We demonstrate that the absorption coefficient profile can be tailored to suit one's need by careful control of the flexible design parameters given to the valence band CQW structure. For the application to an infrared detector with a flat absorptivity over a wider wavelength range than the conventional detectors, the CQW is designed to have broadened absorption spectrum.