Micro-Raman Spectroscopy Study of Vertical GaN Schottky Diode

In this work, the physical and the electrical properties of vertical GaN Schottky diodes were investigated. Cathodo-luminescence (CL), micro-Raman spectroscopy, SIMS, and current-voltage (I-V) measurements were performed to better understand the effects of physical parameters, for example structural defects and doping level inhomogeneity, on the diode electrical performances. Evidence of dislocations in the diode epilayer was spotted thanks to the CL measurements. Then, using 2D mappings of the E-2(h) and A(1) (LO) Raman modes, dislocations and other peculiar structural defects were observed. The I-V measurements of the diodes revealed a significant increase in the leakage current with applied reverse bias up to 200 V. The combination of physical and electrical characterization methods indicated that the electrical leakage in the reverse biased diodes seems more correlated with short range non-uniformities of the effective doping than with strain fluctuation induced by dislocations.

Automated summary

In this study, the physical and electrical properties of vertical GaN Schottky diodes were examined using various characterization techniques including cathodoluminescence (CL), micro-Raman spectroscopy, SIMS, and current-voltage (I-V) measurements. The results indicated the presence of dislocations and other structural defects in the diode epilayer. Furthermore, it was observed that the leakage current in the reverse biased diodes was primarily influenced by short range non-uniformities of the effective doping rather than strain fluctuation induced by dislocations.