Spatial Coherence of Electron Wavefunctions and the Transition from Miniband toStark-Ladder Electric Field Regimes in InGaAs/InAlAs-on-InP Superlattices

摘要

Five In0.53Ga0.47As/ In0.52Al0.48As-on-InP superlattices of various well-to-barrier ratios and miniband widths have been studied by low-temperature photoluminescence, photocurrent, and differential photocurrent spectroscopies. These techniques provide a means of measuring the spatial coherence length of electron wavefunctions in the superlattices. We find that the onset of Wannier-Stark localization occurs when the well-to-well potential drop within the superlattice is between 1.1 and 1.43 times the low-temperature photoluminescence line width for all samples studied. Furthermore, the photoluminescence line width is accurately describable in terms of a simple model for alloy broadening. These findings confirm an intuitive picture for the transition between the miniband and Wannier-Stark electric field regimes in In0.53Ga0.48As/ In0.52Al0.48As-on-InP superlattices.