Improving field emission properties of GaN nanowires by oxide coating

We compared the field emission properties of the following four types of nanowires: GaN nanowire, Ga2O3 nanowire, GaN nanowire with Ga2O3 coating, and Ga2O3 nanowire with GaN coating. The turn-on field values for the GaN, Ga2O3, GaN/Ga2O3, and Ga2O3/GaN nanowires are 4.3, 6.2, 4.7, and 2.6 V/mu m, respectively. It has been found that the oxide coatings effectively improve the field emission capability of GaN nanowires, while the nitride coatings depress electron emission of Ga2O3 nanowires. The corresponding Fowler-Nordheim analysis revealed that the field emission improvement is attributed to the electron accumulation on the coated oxide particles and the interfacial electron redistribution in the nanoscale hetero-structure which results in the shift of Fermi level and the changes of work functions.