Direct measurement for nanoscale vertical carrier diffusion on semiconductor surface-An approach toward scanning diffusion microscopy

Carrier diffusion properties, including the diffusion length, diffusion coefficient, and carrier lifetime are important for photonic devices. In nitride semiconductors, there are many microscopic structures, which have a strong influence on carrier diffusion. In this paper, a method based on the photo-assisted Kelvin-probe force microscope and the confocal time-resolved photoluminescence spectrum at the same position is developed to map simultaneously the topography and the nanoscale vertical carrier diffusion on the semiconductor surface. On the surface without any dislocations, the hole diffusion length and diffusion coefficient are 161 +/- 8 nm and 1.6 +/- 0.2 cm(2)/s, respectively. Near the termination of the dislocation loops on the surface, it can be clearly seen that the diffusion length and diffusion coefficient gradually drop to about 13 +/- 5 nm and 0.02 +/- 0.01 cm(2)/s with a spatial resolution of about 100 nm. Published under an exclusive license by AIP Publishing

Automated summary

This study develops a method to simultaneously map the surface topography and nanoscale vertical carrier diffusion and investigates the influence of microscopic structures on carrier diffusion properties in nitride semiconductors.