The effect of annealing temperature on electrical and structural properties of Rh/Au Schottky contacts to n-type GaN

The effect of thermal annealing temperature on electrical and structural properties of Rh/Au Schottky contacts to n-type GaN (∼4 × 10 17 cm −3 ) has been investigated by current–voltage ( I–V ), capacitance–voltage ( C–V ), x-ray diffraction (XRD) and Auger electron microscopy (AES). Calculations showed that the Schottky barrier height of the as-deposited Rh/Au contact was 0.57 eV ( I–V ) and 0.62 eV ( C–V ), respectively. However, the Schottky barrier height increased with annealing temperature up to 500 °C, reaching maximum values of 0.84 eV ( I–V ) and 1.05 eV ( C–V ). Based on the Auger electron microscopy and x-ray diffraction results, the formation of gallide phases at the Rh/Au/n-GaN interface could be the reason for the increase of Schottky barrier heights after annealing at temperatures 400 °C and 500 °C.