Imaging Electronic Transport in Luminescent Materials with Near Field Microscopy


  Nancy M. Haegel [1,2]  
[1] Physics Department, Naval Postgraduate School
[2] Fulbright Senior Scholar, Hebrew University

  Highly localized carrier generation combined with near field imaging can be used to make optical, contact-free measurements of electronic charge transport.  This “transport imaging” combines the resolution of near-field optics with the topographical imaging and charge generation control of a scanning electron microscope. The technique is related to, but different from standard cathodoluminescence, since it maintains the spatial information of the emitted light. It is possible to determine minority carrier or exciton diffusion lengths from a single optical image, without any electrical contact to the sample, and to map spatial variations in transport properties that are difficult to access in any other way.  Transport can be imagined in all dimensions - bulk materials, thin films and nanostructures – in any luminescent material.  It is also possible to image waveguiding in individual nanostructures under very localized excitation conditions.  Examples will be given from electrical and optical measurements in solar cell materials and GaN and ZnO nanostructures.