EFFICIENT TUNING OF THE CARRIER CAPTURE EFFICIENCY OF QUANTUM-WELLS BY INTRODUCING A BARRIER ASYMMETRY

A GaAs quantum well (QW) placed in an AlGaAs barrier layer of linearly graded composition has been studied by photoluminescence, in order to estimate experimentally the carrier capture efficiency of a QW in an electric field. The introduction of a slight compositional asymmetry ( 3% to 6% Al) between both sides of the QW allows to enhance or drastic ally reduce the capture probability. This tuning is efficient for temp eratures as high as 77 K. Our experimental results, supported by a qua ntum mechanical calculation of the capture probability, suggest novel routes for optimizing QW infrared photodetectors and QW lasers.