Advantage of SiO2 Intermediate Layer on the Electron Injection for Ti/n-Al0.60Ga0.40N Structure

In this work, and experimentally propose inserting an SiO ₂ intermediate layer between the Ti and n-AlGaN layer to improve the electron injection efficiency. When the SiO ₂ intermediate layer is adopted, the SiO ₂ layer can share a part of the applied voltage and then weakens the surface depletion effect, which is confirmed by the capacitance-voltage measurement. Furthermore, the energy bending of the SiO ₂ layer pushes the affinity of Ti to be even higher than the conduction band of the Al _0.60 Ga _0.40 N layer, which then screens the Schottky barrier and favors the election injection. The influence of the thickness of the SiO ₂ intermediate layer is also investigated in this work. When the SiO ₂ layer becomes thick, the tunneling capability of the electrons will be significantly limited due to the increased tunnel region width, leading to increased forward voltage.