Diameter dependence of the minority carrier diffusion length in individual ZnO nanowires

摘要

The minority carrier diffusion length, L_D, was directly measured in individual ZnO nanowires by a near-field scanning photocurrent microscopy technique. The diameter dependence of L_D suggests a diameter-dependent surface electronic structure, particularly an increase in the density of mid-band-gap surface states with the decreasing diameter. This diameter dependence of the surface electronic structure might be a universal phenomenon in wurtzite-type nanostructures, and is critical in interpreting and understanding the effects of surfaces on various material properties.