Photocurrent spectra and WannierStark localization of In0.53Ga0.47As/InP superlattices with different barrier thicknesses
WannierStark localization in a pair of high quality lattice-matched InGaAs/InP superlattices (SL) p-i-n diodes with wide (60 meV) and narrow (14 meV) electron miniband widths has been investigated by room temperature photocurrent (PC) response measurements. PC spectra as well as PC versus reverse bias voltage characteristics of the SL samples exhibit a clear excitonic absorption edge redshifted due to the miniband formation and show distinct Stark ladder transitions, which evolve with the applied electric field. The transition energy fan diagrams are analyzed for the SL model potential structures using transfer matrix calculations. It is found that observed blueshifts of the absorption edge by decreasing the miniband width and by increasing the field exactly coincide with half of the transition miniband width, thus providing the electroabsorption modulation with InGaAs/InP SLs. Good agreement of the transition energies is obtained between theory and experiment, using band offset and effective mass parameters proposed by Gershoni et al. [Phys. Rev. B38 (1988) 7870].
ingaas/inp electroabsorption semiconductor superlattice stark effect