Ni and Ni silicide Schottky contacts on n-GaN

The electrical characteristics of Ni and NiSi Schottky diodes on n-GaN have been investigated as a function of annealing. Ni diodes were found to be stable up to 500 degrees C for 1 h in sequential annealing, with a barrier height phi (I-V) of 0.8-0.9 eV and an n factor of similar to 1.1. The barrier height deduced from C-V measurements, phi (C-V), was typically 0.15 eV higher than phi (I-V). At 600 degrees C the diodes failed, and Ga was found to migrate into the Ni layer. NiSi diodes were stable up to 600 degrees C for 1 h, phi (I-V) was found to be about 0.8-1 eV with an n-factor of about 1.15. The value of phi (C-V) was between 0.3 to 0.6 eV higher than phi (I-V), consistent with the notion of the presence of a thin insulating layer at the NiSi/GaN interface. The electrical characteristics obtained in this study are also compared with those obtained for Pt and PtSi Schottky diodes on n-GaN. (C) 1998 American Institute of Physics. [S0021-8979(98)02714-5].