Synthesis of p-Type Gallium Nitride Nanowires for Electronic and Photonic Nanodevices

Magnesium-doped gallium nitride nanowires have been synthesized via metal-catalyzed chemical vapor deposition. Nanowires prepared on c-plane sapphire substrates were found to grow normal to the substrate, and transmission electron microscopy studies demonstrated that the nanowires had single-crystal structures with a 〈0001〉 growth axis that is consistent with substrate epitaxy. Individual magnesium-doped gallium nitride nanowires configured as field-effect transistors exhibited systematic variations in two-terminal resistance as a function of magnesium dopant incorporation, and gate-dependent conductance measurements demonstrated that optimally doped nanowires were p-type with hole mobilities of ca. 12 cm2/V·s. In addition, transport studies of crossed gallium nitride nanowire structures assembled from p- and n-type materials show that these junctions correspond to well-defined p−n diodes. In forward bias, the p−n crossed nanowire junctions also function as nanoscale UV-blue light emitting diodes. The new synthesis of p-type gallium nitride nanowire building blocks opens up significant potential for the assembly of nanoscale electronics and photonics.