AMBIPOLAR DIFFUSION ANISOTROPY INDUCED BY DEFECTS IN NIPI-DOPED IN0.2GA0.8AS GAAS MULTIPLE-QUANTUM WELLS/

The influence of strain-induced defects on the ambipolar diffusive tra nsport of excess electrons and holes in the delta-doped InGaAs/GaAs mu ltiple quantum well system has been examined with a new technique call ed electron-beam-induced absorption modulation (EBIA). The excess carr ier lifetime and diffusion coefficient are obtained by a one-dimension al diffusion experiment that utilizes EBIA. An anisotropy in the ambip olar diffusion along both high-symmetry [110] directions is found, and this is seen to correlate with the distribution of dark line defects observed in cathodoluminescence.