A new method for direct extraction of ambipolar diffusion length in a thin film by scanning photoluminescence microscopy

Abstract

Abstract In this study, we demonstrate a new method of scanning photoluminescence (PL) microscopy (SPLM) to directly extract the ambipolar diffusion length in a GaAs thin film. The PL intensity of the GaAs thin film was recorded while the excitation source scanned along a 400 nm wide slit between the metal masks to avoid the influence of surface recombination and light scattering at the sample edge. The experimental SPLM profile showed a simple-exponential-decay functional form and was numerically verified. A fitted decay length of 723 nm was extracted, which represents the ambipolar diffusion length of the GaAs thin film and agrees well with our previous study.