Ti/Al p-GaN Schottky barrier height determined by C-V measurements

Data are presented on the rigorous method of capacitance-voltage (C-V) measurements to the barrier height of Ti/Al p-GaN Schottky junction. For a sample with Hall concentration of 5.5 × 1016/cm3 the upper limit of the modulation frequency leading the full response of the activated carriers is defined as 1.5 kHz from the capacitance versus modulation frequency (C-f) plot. The activation energy of the Mg acceptors determined from the temperature-dependent C-f plot is 0.12 eV. The barrier height estimated with this activation energy and the intercept voltage of the 1/C2-V plot drawn with the 1.5 kHz C-V data is 1.43 eV at 300 K and 1.41 eV at 500 K. This is the most reliable barrier height ever reported. A reliable room temperature C-V doping profile is demonstrated using the 1.5 KHz modulation, which is sensitive enough to resolve the presence of a ∼15 nm thin highly doped (8 × 1018/cm3) layer formed near the surface.