Formation of Rough GaN Surface by Hydrogen Plasma Treatment and Its Application to Field Emitter

N-type GaN layers doped with Si are grown on sapphire substrates with AlN buffer layers by the metalorganic chemical vapor deposition method. The electron density is 2×10 17 cm -3 . The GaN surface is treated with hydrogen (H 2 ) plasma produced by supplying microwave power. Etching of GaN with H 2 plasma leads to the formation of a roughened GaN surface. An enhancement of the electric field at the roughened surface makes it possible to reduce the average electric field between the anode electrode and the sample surface for electron emission. The turn-on electric field for the electron emission is estimated to be as low as 12.4 V/µm.