Characterization of carrier transport behavior of specific type dislocations in GaN by light assisted KPFM

Abstract

The direct characterization of carrier transport behavior at different types of dislocations in GaN is still questionable due to the current lack of feasible strategy. Herein, we developed a method by combining ultraviolet light-assisted Kelvin probe force microscope with defect selective etching technology. The dislocation types could be confirmed by the shape of the etching pit, and the photogenerated carrier recombination behavior at specific dislocation. Thus, it can be characterized by ultraviolet light-assisted Kelvin probe force microscope, which paves the way for analysis of carrier transport behavior at different types of dislocations in GaN. The screw dislocations are found to be the main non-radiative recombination centers, and mainly responsible for leakage current in GaN based device. This shows higher surface potential and higher electron concentration due to the donor defects introduced during dislocation growth. Conversely, a barrier is generated around the edge and mixed dislocations, which could suppress the non-radiative recombination at the dislocation. The present work provides a feasible way to direct characterization of specific type dislocations in GaN. Moreover, this method can be used to characterize other III-nitride materials.