Abstract

We use excitonic effects in thin GaAs quantum-well stripline samples to generate, propagate, and detect femtosecond electrical signals.¹ The time dependence of the initial photocurrent transient depends sensitively on the bias and excitation conditions. One possible explanation for this is a velocity-overshoot effect, which is strong because the carriers that we excite are initially at the band gap, with no excess energy. In this presentation, we point out that in metal-semi-insulating semiconductor contact systems, the actual electric field experienced by the quantum-well excitons can be highly nonuniform,² making quantitative comparison with theory difficult. In fact, Monte-Carlo studies of carrier transport should be developed to account for this effect.

© 1990 Optical Society of America