Effect of copper phthalocyanine (CuPc) interlayer on the electrical characteristics of Au/n-GaN Schottky rectifier

Electrical properties of Au/n-GaN Schottky rectifier with copper pthalocyanine (CuPc) interlayer were investigated using current–voltage (I–V), capacitance–voltage (C–V) and conductance–voltage (G–V) characteristics. The barrier height obtained for the Au/CuPc/n-GaN Schottky diode was higher than that of the Au/n-GaN Schottky diode. This could be associated with the presence of the CuPc interlayer influencing the space-charge region of the Au/n-GaN structure. The Au/CuPc/n-GaN Schottky structure exhibits higher ideality factor, indicating the higher interface inhomogeneity in Au/CuPc/n-GaN as compared to Au/n-GaN Schottky structure. The density of interface states was extracted using I–V, C–V, and G–V characteristics. The results showed that the introduction of CuPc interlayer facilitated the reduction of interface state density (NSS) of Au Schottky contact to n-GaN. Particularly, the NSS obtained from frequency-dependent C–V characteristics was lower than that determined from forward I–V characteristics, which could be attributed to the inhomogeneous distribution of NSS at Schottky interface.