Reduced Schottky Barrier of Metal/4H-SiC Junction with Ultrathin Aluminum Oxynitride Interlayer

Abstract

The electrical characteristics of SiC Schottky diode depend strongly on the interface energy barrier. Lower Schottky barrier of Schottky diode gives advantages that improve the power efficiency and acquire fast switching. In this work, the Schottky barrier of metal/SiC junction is reduced notably with an ultra-thin (down to 1.0nm) aluminum oxynitride (AlON) interlayer inserted at the junction interface. The ultra-thin film layer was deposited by using the RF magnetron sputtering with the in-situ flashing. The Schottky barriers of metal/AlON/SiC and metal/SiC junctions were obtained by performing current-voltage (I-V), capacitance-voltage(C-V), and internal photoemission (IPE) measurements. The adjustment of Schottky barrier with an interlayer is normally considered to be due to the potential change driven by fixed charges in the interlayer or Fermi-level depinning associated with the suppression of metal-induced gap states. In this case, the Fermi-level pinning factor remained almost unchanged, implying that the surface states of SiC is NOT the main factor of the observed Schottky barrier reduction.