Effects of post-deposition annealing on temperature-dependent electrical characteristics of Ni/(Al_0.1Ga_0.9)₂O₃/4H-SiC Schottky barrier diodes

We investigated morphological properties of vertical heterojunction Schottky diodes based on (Al_0.1Ga_0.9)₂O₃/4H-SiC (AGO) thin films and analyzed the effect of post-annealing on their temperature-dependent electrical characteristics over the temperature range of 298 to 498 K. The AGO films were deposited using radio frequency sputtering and analyzed the as-deposited and N₂-annealed films at 950 °C in a nitrogen atmosphere. The N₂-annealed sample exhibited an estimated grain size of 63.2 nm compared to an average grain size of 43.6 nm in the as-deposited samples. As temperature increased, the barrier height (Φ_b) exhibited an upward trend, while the ideality factor (n) showed a declining trend. The calculated values of Φ_b and n in the as-deposited sample varied from 1.11 eV and 2.76 at 298 K to 1.47 eV and 1.37 at 498 K. The Schottky diode’s I–V characteristics, which vary with temperature, exhibited a Gaussian distribution. The temperature-dependent electrical characteristics of the Schottky diodes have shown a Gaussian distribution, yielding a mean barrier height of 2.08 eV and a standard deviation of 0.22 V for the as-deposited sample. In contrast, the N₂-annealed sample’s mean barrier height was 1.16 eV, with a standard deviation of 0.13 V.