Effect of Pressure on Field Emission Characteristics of GaN Thin Films Prepared by Pulsed Laser Deposition

A series of GaN thin films were prepared by pulsed laser deposition at different deposition pressure on n-type Si(100) substrates. The field emission measurement results show that the turn-on field Eon of GaN films is increasing with the deposition pressure increasing, and the FN plots show a linear relationship in the high-field region for all the samples, suggesting that the emission current originate from a quantum mechanical tunneling process. GaN thin film has the best FE characteristics with the lowest E-on of 0.95 V/mu m at 0.1 Pa, and largest current density of 28 mu A/cm(2) at the field of 3 V/mu m. GaN film structure and surface morphology were characterized by X-ray diffraction and atomic force microscopy, respectively. The diffraction peak of the (002) plane of the wurtzite-type hexagonal GaN is observed. When deposition pressure is larger the amorphous thin film can be obtained, and the field emission properties become deterioration. Therefore, the deposition pressure is essential to enhance field emission properties of GaN thin films, which is through appropriate regulation of crystal structure and surface morphology controlling.