Abstract:
The evolution of Ni/Au and Ni/Ir/Au metal contacts deposited on AlGaN was investigated at
different annealing temperatures. The samples were studied with electrical and chemical
composition techniques. I-V characteristics of the Schottky diodes were optimum after 500
and 600 ºC annealing for Ni/Au and Ni/Ir/Au based diodes, respectively. The depth profiles
of the contacts were measured by x-ray photoelectron spectroscopy and time of flight
secondary ion mass spectroscopy. These chemical composition techniques were used to
examine the evolution of the metal contacts in order to verify the influence the metals have
on the electrical properties of the diodes. The insertion of Ir as a diffusion barrier between Ni
and Au effected the electrical properties, improving the stability of the contacts at high
temperatures. Gold diffuses into the AlGaN film, degrading the electrical properties of the
Ni/Au diode. At 500 ºC, the insertion of Ir, however, prevented the in-diffusion of Au into the
AlGaN substrate.
