Waveguide effect in quantum well infrared photodetectors

摘要

Abstract: The possibility of quantum efficiency enhancement in GaAs/AlGaAs quantum well infrared photodetectors (QWIP) by means of waveguide propagation of radiation in superlattice is investigated in this paper. Epitaxial structures for photodetector manufacturing were grown by low pressure metal organic chemical vapor deposition (LP-MOCVD) on high doped (3 $DOT 10$+18$/ cm$+$MIN@3$/) n-type substrates. The use of these high doped conductive substrates allows us to achieve an abrupt change of refractive index on interface between superlattice and substrate. Due to this fact optical restriction of electromagnetic wave propagation along superlattice arises. A fine structure with peaks ($Delta$lambda equals 0.1 mkm) was found on the photosensitivity spectra of this QWIP ($lambda$-max$/ equals 9 mkm). We consider this effect can be explained by arising of standing waves in volume of QWIP. It indicates one possibility of waveguide propagation of radiation in QWIP structures grown on high doped conductive substrates. The use of QWIP on conductive substrates allows us to increase a quantum efficiency and to simplify the technology QWIP-lines manufacturing. !7