Nanoscale mapping of dopant distributions in InP current blocking layers

A novel application of combined electron and ion beam techniques for the study of dopant distributions in InP-based structures is described. It is demonstrated that dopant distributions in InP may be mapped from transmission electron microscope images with spatial resolution /spl sim/10 nm and compositional sensitivity /spl sim/10/sup 17/ cm/sup -3/. Applications to current blocking layers in InP laser diode structures are illustrated. Pertinent experimental observations relating to the origin of this unexpected dopant contrast are discussed.