Cu3Ge Schottky contacts on n-GaN

Abstract

The electrical properties and thermal stability of \(\varepsilon _1 - Cu_3 Ge\) (hereafter referred to as \(Cu_3 Ge\)) Schottky contacts to n-GaN as a function of the Ge concentration and annealing temperature are studied. Upon rapid thermal annealing the \(Cu_3 Ge\)/n-GaN Schottky diode is formed at 300 °C and is stable up to 650 °C. At 700 °C the agglomeration occurs in the \(Cu_3 Ge\) films. For the Cu-25 at % Ge films the ideality factor, n, barrier height, \(\phi _{B0}\), and flat band barrier height, \(\phi _{BF}\), of the \(Cu_3 Ge\)/n-GaN diodes are in the ranges of 1.22–1.36, 0.53–0.72 eV, and 0.65–0.97 eV, respectively, being decreased with the annealing temperature. Higher Ge concentration in the Cu-35 at % Ge films results in larger n, \(\phi _{B0}\), and \(\phi _{BF}\) of \(Cu_3 Ge\)/n-GaN Schottky diodes. The \(Cu_3 Ge\) film is expected to be a suitable candidate for stable Schottky contacts to n-GaN at elevated temperatures.