Narrow band infrared detection in multiquantum well structures

A theoretical analysis is performed for photoexcitation of carriers from a quantum well state into a superlattice subband. The parameters of the device structure are chosen so that (a) the first excited state of the quantum well lies within the lowest subband of the superlattice and (b) the lowest subband is narrow. The degeneracy of the first excited state with the subband provides resonant enhancement of photoexcitation into the subband while the subband extrema provide long-wavelength and short-wavelength cutoffs. The response band and bandwidth can be tailored and there is the possibility of high-temperature operation associated with the narrow band response.