Annealing temperature dependence of TiB2 schottky barrier contacts on n-GaN

Abstract

The annealing temperature (25-700°C) dependence of Schottky contact characteristics on n-GaN using a TiB 2 /Ti/Au metallization scheme deposited by sputtering is reported. The Schottky barrier height increased from 0.65 to 0.68 eV as the anneal temperature was varied from 25°C to 350°C and decreased to 0.55 eV after annealing at 700°C. The barrier height showed no measurable dependence on measurement temperature up to 150°C. The elemental profile obtained from samples annealed at 350°C showed limited Ti diffusion from the elemental Ti layer into the gold layer. Annealing at 700°C produced significant out-diffusion of this layer, while the TiB 2 layer retained its stability. These contacts show promise for applications requiring good thermal stability, such as power amplifiers, but much more work is needed to establish their long-term reliability. In addition, TiB 2 has a strong propensity for oxidation, and it is imperative that overlayers such as Au be deposited in the same deposition chamber.

Ir-Based Schottky and Ohmic Contacts on n-GaN

“…The Ir may be a superior choice to boride contact schemes for GaN because the latter are prone to oxidation. [36][37][38][39][40][41]…”