Fabrication and Electrical Characterization of GaAs/GaN Junctions

We fabricate p + -GaAs/n-GaN and n + -GaAs/n-GaN junctions using surface activate bonding and measure their capacitance-voltage and current-voltage characteristics. We find that the characteristics of the two junctions are close to each other, which suggests that the band profiles of GaN layers in the two types of junctions are almost the same, i.e., the Fermi-level pinning occurs at the GaAs/GaN interfaces. Breakdown occurs at a reverse bias voltage ≈ -60 V in both junctions. The observed breakdown voltage corresponds to an electric field of as high as ~ 1.6 MV/cm, which is comparable to a reported breakdown field of GaN. We also excite minority electrons in the p + -GaAs layer using a 488-nm laser and successfully observe the photocurrent due to the transport of minority electrons across the reverse-biased GaAs/GaN interfaces.