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

Abstract

AbstractThe 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 °C, 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 °C, 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 °C. 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.