Intensity-dependent ultrafast dynamics of injection currents in unbiased GaAs quantum wells

The intensity dependence of optically‐induced injection currents in unbiased GaAs semiconductor quantum wells grown in [110] direction is investigated theoretically for a number of well widths. Our microscopic analysis is based on a 14 × 14 band k · p method in combination with the multisubband semiconductor Bloch equations. An oscillatory dependence of the injection current transients as function of intensity and time is predicted and explained. It is demonstrated that optical excitations involving different subbands and Rabi flopping are responsible for this complex dynamics. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) In solid state systems of sufficiently low symmetry optical excitation can be used to generate electrical currents without an applied bias. Here, the authors theoretically study the intensity dependence of such injection currents generated by femtosecond laser pulses in GaAs semiconductor quantum wells grown in [110] direction. It is predicted that the direction of the injection current changes as function of the laser pulse intensity.