Annealing and measurement temperature dependence of W2B5-based rectifying contacts to n-GaN

Abstract The thermal stability and measurement temperature dependence of Schottky contact characteristics on n -GaN using a W 2 B 5 /Ti/Au metallization scheme was studied using current–voltage ( I – V ), scanning electron microscopy (SEM) and Auger electron spectroscopy (AES) measurements. The elemental profile obtained from samples annealed at 350 °C showed some titanium diffusion into the gold layer but little other difference from the as-deposited wafer. Annealing at 700 °C produced significant diffusion of titanium. The Schottky barrier height increased with anneal temperature up to 200 °C, reaching a maximum value of 0.65 eV, but decreased at higher annealing temperatures. The reverse breakdown voltage from diodes fabricated using the W 2 B 5 -based contacts showed a similar dependence. The reverse current magnitude was larger than predicted by thermionic emission alone. The barrier height showed only minor changes with measurement temperature up to 150 °C.