GAAS ASYMMETRICALLY DOPED N-I-P-I-SUPERLATTICES FOR 10-MU-M INFRARED SUBBAND DETECTOR AND MODULATOR APPLICATIONS

A theoretical framework for the design of asymmetrically doped n-type n-i-p-i- superlattices for subband detector applications in the 10 mum spectral range is described. Excellent agreement is found with the su bband absorption spectra measured in a series of GaAs n-type n-i-p-i- samples and oscillator strengths, transition energies, and dipole matr ix elements comparable with conventional quantum-well heterostructure detectors are found. Pronounced IR-absorption modulation by optical pu mping with band-gap radiation is seen, due to the enhanced interband r ecombination time resulting from the type-II n-i-p-i- potential. The p rospective advantages of n-type n-i-p-i- devices for the detection and modulation of 10 mum radiation are discussed.