Study of low-frequency excess noise in GaN thin films deposited by RF-MBE on intermediate-temperature buffer layers

Low-frequency excess noise was measured in a series of GaN epitaxial films deposited by RF-plasma assisted molecular beam epitaxy (MBE). The GaN epita xial layers were grown on double buffer layers, each consisting of an inter mediate-temperature buffer layer (ITBL) deposited at 690 degreesC and a con ventional low-temperature buffer layer grown at 500 degreesC. The Hooge par ameters for the as-grown films were found to depend on the thickness of ITB L with a minimum value of 7.34 x 10(-2) for an optimal ITBL thickness of 80 0 nm. The observed improvements in the noise properties are attributed to t he relaxation of residual strain within the material, leading to a correspo nding reduction in crystalline defects.