Field emission from GaN and (Al,Ga) NGaN nanorod heterostructures

Vacuum field emission from GaN and (Al,Ga) NGaN nanorods with pyramidal tips has been measured. The turn-on fields, defined at a current density of 0.1 μA cm2, were found to be 38.7 and 19.3 Vμm, for unintentionally doped GaN and (Al,Ga) NGaN nanorods, respectively. The 5 nm (Al,Ga)N layer reduced the electron affinity at the surface, thereby lowering the turn-on field and increasing the current density. The nanostructures exhibit a field enhancement factor of approximately 65 and the work function of the (Al,Ga) NGaN nanorod heterostructure was estimated to be 2.1 eV. The stability of the emission characteristics and the simple fabrication method suggest that intentionally doped and optimized (Al,Ga) NGaN nanorod heterostructures may prove suitable for field-emission device.