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/μm, 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.