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

P Deb, Birck Nanotechnology Center, School of Materials Engineering, Purdue University
Tyler Westover, Purdue University - Main Campus
Ho Young Kim, Birck Nanotechnology Center and Department of Physics, Purdue University
Timothy Fisher, Birck Nanotechnology Center, Purdue University
Timothy D. Sands, Purdue University

Abstract

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.