Characteristics of RF reactive sputter-deposited Pt/SiO2/n-InGaN MOS Schottky diodes

All RF sputtering-deposited Pt/SiO2/n-type indium gallium nitride (n-InGaN) metal-oxide-semiconductor (MOS) diodes were investigated before and after annealing at 400 degrees C. By scanning electron microscopy (SEM), the thickness of Pt, SiO2, n-InGaN layer was measured to be similar to 250, 70, and 800 nm, respectively. AFM results also show that the grains become a little bigger after annealing, the surface topography of the as-deposited film was smoother with the rms roughness of 1.67 nm and had the slight increase of 1.92 nm for annealed sample. Electrical properties of MOS diodes have been determined by using the current-voltage (I-V) and capacitance-voltage (C-V) measurements. The results showed that Schottky barrier height (SBH) increased slightly to 0.69 eV (I-V) and 0.82 eV (C-V) after annealing at 400 degrees C for 15 min in N-2 ambient, compared to that of 0.67 eV (I-V) and 0.79 eV (C-V) for the as-deposited sample. There was the considerable improvement in the leakage current, dropped from 6.5 x 10(-7) A for the as-deposited to 1.4 x 10(-7) A for the 400 degrees C-annealed one. The annealed MOS Schottky diode had shown the higher SBH, lower leakage current, smaller ideality factor (n), and denser microstructure. In addition to the SBH, n, and series resistance (R-s) determined by Cheungs' and Norde methods, other parameters for MOS diodes tested at room temperature were also calculated by C-V measurement. (C) 2014 Elsevier Ltd. All rights reserved.