Annealing Temperature Dependence of TiB_2 Schottky Barrier Contacts on n-GaN

摘要

The annealing temperature (25-700degC)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 25degC to 350degC and decreased to 0.55 eV after annealing at 700degC.The barrier height showed no measurable dependence on measurement temperature up to 150degC.The elemental profile obtained from samples annealed at 350degC showed limited Ti diffusion from the elemental Ti layer into the gold layer,while the TiB_2 layer retained its stability.These contacts show promise for applications requiring good ther-mal stability,such as power amplifiers,but much more work is needed to establish their long-term reliability.In addition,TiB_2has a strong propensity for oxidation,and it is imperative that overlayers such as Au be deposited in the same deposition chamber.