Field emission properties of self-assembled InN nano-structures: Effect of Ga incorporation

This work reports the field emission properties of InN and In-rich InGaN nano-structures. Pyramid InN with a tip-like feature exhibits field emission characteristics in a vacuum. Adding Ga into InN reduces the surface roughness and degrades the turn-on electric field. However, when the Ga content is as low as 2%, the same roughness of the film is almost maintained and the barrier height is lower than that of InN. Ultraviolet photoemission spectroscopic analyses show a gradual reduction on the surface work function of InGaN films when the Ga content increases. From the perspectives of surface roughness and surface work function, the In0.98Ga0.02N sample has the best field emission properties of all of the samples studied herein. A turn-on field of 11 V/μm and an emission current density of 1×10−2 A/cm2 (at 30 V/μm) in the In0.98Ga0.02N epilayer were achieved.