Enhanced electron field emission from oriented columnar AlN and mechanism

(002) oriented AlN thin films with a columnar microstructure fabricated by vapor phase deposition with a sample bias exhibit excellent field emission properties. The field emission current density increases with smaller film thickness, and at a thickness of 400nm, the current density reaches 9.9μA∕cm2 and the turn-on field is close to 5V∕μm. Atomic force microscopy discloses nanoscale protrusions on the surface that greatly expand the emission area and efficiency. The Fowler-Nordheim plot reveals a linear dependence under low electric field (<17V∕μm), suggesting that the emission current originates from the quantum tunneling effect.