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

Vacuum field emission from GaN and (Al,Ga)N/GaN nanorods with pyramidal tips has been measured. The turn-on fields, defined at a current density of 0.1 mu A/cm(2), were found to be 38.7 and 19.3 V/mu m, for unintentionally doped GaN and (Al,Ga)N/GaN 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)N/GaN 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)N/GaN nanorod heterostructures may prove suitable for field-emission device. (c) 2007 American Vacuum Society.