New all-optical pump-and-probe technique for the investigation of the ambipolar in-plane diffusion in n-i-p-i doping superlattices

We report on a new all-optical pump-and-probe technique for the investigation of the fast in-plane ambipolar diffusion process in n-i-p-i doping superlattices. This new technique allows not only the determination of the ambipolar diffusion coefficient but also the spatially resolved investigation of the stationary distribution of the optically induced excess carriers. In our n-i-p-i sample we have measured an ambipolar diffusion coefficient in the range of 10⁴ cm²/s