Electrical characteristics and interfacial reactions of rapidly annealed Pt/Ru Schottky contacts on n‐type GaN

Abstract

The electrical properties and interfacial reactions of Pt/Ru Schottky contacts on n-type gallium nitride (GaN) have been investigated as a function of annealing temperature. The calculated Schottky barrier height (SBH) of the as-deposited Pt/Ru Schottky contact is found to be 0.69 eV current-voltage (I-V) and 0.76 eV capacitance-voltage (C-V). Experimental results showed that the SBHs are increased on increasing the annealing temperature. When the contact is annealed at 600 8C, a maximum barrier height is obtained and the corresponding values are 0.87 eV (I-V) and 0.99 eV (C-V). The Norde method was also employed to extract the barrier height of Pt/Ru Schottky contacts and the values are 0.70 and 0.86 eV for the samples as-deposited and annealed at 600 8C, which are in good agreement with those obtained from the I-V measurement. Shifts of the surface Fermi level are measured with the change in position of the Ga 2p core level peak. Based on the X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) studies, the formation of gallide phases at the Ru/Pt/n-GaN interface could be the reason for the increase in SBH at elevated temperatures. Atomic force microscopy (AFM) results showed that the surface morphology of the Pt/Ru Schottky contact did not change significantly even after annealing at 600 8C. These results point out that a Pt/Ru Schottky contact may be a suitable candidate for the fabrication of GaN-based high-temperature device applications.

Effect of annealing on the electrical performance of N-polarity GaN Schottky barrier diodes

“…It is obvious that the obtained GaN film can be etched by KOH, indicating that its lattice polarity is N-polarity. The crystalline quality and surface morphology of the N-polarity GaN can be found in our previous work [23] . The crystalline quality of the N-polarity GaN in our work is comparable to that of metalpolarity GaN, as shown in Table 1.…”