Field electron emission from GaN/W tips

Field electron emission studies have been performed on tungsten (W) tips deposited with gallium nitride (GaN). The deposition of GaN was carried out by plasma assisted reactive evaporation of gallium in nitrogen environment. The structural features and chemical composition of the GaN film were determined by employing scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) techniques, respectively. SEM showed ball-like morphology whereas EDX revealed that the GaN film was rich in gallium. The GaN/W tip was annealed at 1000 K for 600 s in order to ascertain the stability of the film. The field emission current–voltage (I–V) measurements were made on as-deposited and annealed GaN/W tips. After annealing, there was a remarkable improvement in the field emission current as compared to the as-deposited state. The field emission current–time (I–t) curves were recorded from the as-deposited and the annealed-tip states. It was found that annealing caused a significant reduction in the relative fluctuations in the emission current from a level of about 20% to ∼5%. Field emission micrographs were also recorded to observe the morphological changes occurring on the GaN/W tip surface during the experiment.